Men and women are two individuals who are biologically created differently. Aside from the fact that they do not have the same physical appearances, the internal organs of man and woman differ too. This is especially true when it comes to their reproductive organs. Males do not bear a child but they have different organs that make pregnancy possible for females. What are the parts of the male reproductive system and their functions? What cells are important for the production of fertilized eggs in females? How important are the accessory organs of the male reproductive system?
To understand reproduction in humans, you must recognize first the basic units responsible for the formation and propagation of life—the sex cells. These are also known as gametes, which are unique for males and females. The male sex cells are called sperm cells, while the female sex cells are called ova (singular, ovum) or egg cells. Gonads are the organs that produce sex cells. The main function of the male reproductive system is to produce sperm cells. This plays an important role for life to begin, as life begins with the union of the sperm and ovum. This union of male and female sex cells is a process known as fertilization. This is essential for humans and all other living organisms to persist on Earth.
Parts of the Male Reproductive System
The male reproductive system consists of the testes, scrotum, epididymis, vas deferens, seminal vesicle, prostate gland, Cowper’s gland, penis, and urethra.
The Testes
The testicles or testes (singular, testis) are the major organs of the male reproductive system. These are the gonads that produce sperm cells. In addition, these gonads are also responsible for the production the male sex hormone called testosterone.
The testes are found inside a pouch of skin called the scrotum. It protects the testes from changes in temperature. In fact, the scrotum has a lower temperature compared to the rest of the body. Its size also changes to maintain the right temperature for sperm production.
For example, when the body is cold, it shrinks to keep the testes warm. But when the body is warm, it becomes loose to get rid of the extra heat in the body. This is to ensure that testes will have a normal production of sperm cells.
The Epididymis and the Vas Deferens
The epididymis is a long coiled tube located on the back of each testicle. It serves as the temporary storage compartment for the sperm cells after they have been produced. Sperm cells become mature here when they acquire motility or the capacity to move and to fertilize. When the sperm cells become mature, they travel from the epididymis to the vas deferens. This tube will then transport the sperm cells to the urethra. The surgical process of vasectomy blocks or cuts the vas deferens. This is a type of permanent contraception and will prevent the male that underwent the procedure from impregnating a female.
The Accessory Glands
The accessory glands are responsible for the discharge of the fluid part of the semen. The semen is a mixture of sperm and seminal fluid. It provides the fluid in which sperm are transported. It is important for the nutrition and motility of the sperm during transport to the female reproductive system. The fluid part comes from multiple glands. The prostate gland is in charge of producing fluids that serve to nourish sperm. There is also a pair of Cowper’s glands or bulbourethral glands, which produce fluids that protect the sperm during ejaculation. The seminal vesicles can also be found as a pair and produce the majority of the fluids in semen.
The Urethra
The urethra is a tube that serves as a passageway for both the urine and semen with the sperm to the outside of the body. A valve within the urethra prevents the urine and semen from mixing.
The Penis
The penis is a tubular organ that hangs in front of the male’s body. This also makes up the male’s external genital. It is responsible for delivering the semen with sperm into the female’s reproductive system. It is covered by a foreskin which is removed during circumcision. Circumcision is usually done to lower the risk of infections and other diseases.
Did You Know?
The normal volume of semen ranges from 2 mL to 5 mL. The normal number of sperm cells, on the other hand, is from 15 million to around 200 million sperm per millimeter. If the number of sperm goes below 15 million, the person is considered to have low sperm count and may have difficulty in successfully fertilizing the egg cells in females.
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One of the wonders of being a female is the ability to bear a child. Unlike males, females have the capacity to carry a child in their womb until the right time comes for the child to be born. This is made possible with the different parts of the female reproductive system. For nine months, a mother nourishes her child in her womb. What are the parts of the female reproductive system and their functions? What is the pathway of the sperm cells as they move through the female reproductive tract to allow fertilization to take place? How can a female allow the development of her child for nine months during her pregnancy period?
Parts of the Female Reproductive System
The Ovaries
The ovaries are a pair of small almond-shaped structures that are considered major organs of the female reproductive system. These gonads produce eggs (or egg cells) that are necessary for fertilization to take place. They also secrete sex hormones specifically estrogen and progesterone. Estrogen is a female sex hormone that controls and regulates the development of the female reproductive system and secondary sex characteristics. It is also in charge of changes that a woman undergoes before and during pregnancy. Progesterone is also a sex hormone in females, and it is in charge of the maintenance of the woman’s uterus during pregnancy.
The Fallopian Tubes
The fallopian tubes are two tubes that extend from the ovaries to the uterus. They are also known as the oviducts. The eggs, after being released by the ovaries, are caught by fingerlike projections at the end of each fallopian tube. These finger-like projections are known as fimbriae. The eggs then travel down the fallopian tubes. In one of these tubes, the egg cell meets the sperm cell. Therefore, this is where fertilization takes place.
Tubal ligation, much like vasectomy that was discussed in the previous lesson, is a surgical process of contraception. It involves tying, blocking, or cutting the fallopian tubes in order to prevent pregnancy. This means that a female will not get pregnant even if sexual intercourse is performed.
The Uterus
The uterus is a hollow, muscular, and pear-shaped organ. It is also known as the female’s womb. It is where the fertilized egg will develop and grow into a fetus. It has an endometrium (uterine lining) that is its soft and smooth inner lining. When the egg is fertilized, the endometrium thickens to prepare for the pregnancy. If the egg is not fertilized, part of the endometrium is shed and leaves the body as menstrual blood in the process known as menstruation. This process begins during teenage years, particularly during puberty.
The Cervix
The cervix is a narrow structure that connects the uterus to the vagina. It serves as a passageway for the sperm and menstrual flow. During delivery of the baby, it expands to allow the baby to pass through it.
The Vagina
The vagina is a passageway where sperm can enter through sexual intercourse. It is also called the birth canal where the baby is normally delivered. During normal delivery, it expands to let the baby out of the vulva or the female’s external genitalia when giving birth.
Take note that one important difference between males and females is the exit point for urine and sex cells. In males, the urethra inside the penis serves as the exit point for both urine and sperm cells. In females, the urethra is for urine, while the vagina is for the exit of menstrual fluid, for the penetration of the penis during sexual intercourse, and the exit of the baby during childbirth.
Did You Know?
An ectopic pregnancy happens when the developing embryo implants or settles in locations other than the uterus. The fetus cannot survive in this case, and also threatens the life of the mother.
Click here to view the Female Reproductive System.
If you are to look at your baby pictures now, you will see how much you have changed physically. You grew taller, and your body size became bigger. Aside from the physical changes, you might have also experienced behavioral and mental changes. You are now able to read and write, and at the same time, you can feel varying emotions. All these changes are normal for a child who grows and continues to develop. But the changes that young males and females experience are not always the same. What are some of the changes that males and females experience during their puberty?
Puberty
Puberty is a stage of human growth and development where a person becomes physically mature. This stage of reproductive maturity means that the person is now physically capable and physically ready to reproduce.
When boys and girls reach puberty, different changes in their bodies occur. A pea-shaped gland found in the brain called the pituitary gland releases hormones that jumpstart puberty. Secondary sexual characteristics or the changes that happen during puberty are due to the sex hormones from the testes and ovaries. In males, testosterone is the hormone responsible for these secondary sexual characteristics. On the other hand, estrogen and progesterone are responsible for the changes in females.
Physical Changes in Males
Puberty in males happens between the age of 12 and 16. During puberty, males produce more testosterone. Testosterone is responsible for the development of the secondary male characteristics of males such as deeper voices, growth of more body and facial hair, broader shoulders, bone development, and the production of millions of functional sperm cells. It also controls the growth, development, and maintenance of sex organs.
At the onset of puberty, the first change that can be observed is the increase in the size of the testicles. After the increase in the size of testicles, the penis also increases in size. During puberty, the testosterone also produces more sperm cells, making a boy now sexually mature to fertilize an egg. During this period, boys may experience ejaculation (release of sperm-containing semen) while sleeping known as wet dreams. This is normal since the body produces more testosterone.
Another notable change in males is the growth of facial hairs, as well as the growth of hair in different parts of the body. Such parts include the pubic area, legs, and underarms. Also, hearing the voice of the boys crack is normal as their voices start to deepen at this stage. This is due to the changes happening to the voice box (larynx) and vocal cords. Once the larynx reaches adult size, the cracking of the voice will stop. This is the time when Adam’s apple also becomes prominent.
Boys may also experience oilier skin and increased sweating, which may result in the growth of pimples or acne. Increased physical activities during these years lead to more sweating that can also cause body odor. Their muscles develop, shoulders broaden, and there is a noticeable increase in height.
Physical Changes in Females
Female reproductive organs form before birth but do not mature until puberty. Girls experience puberty at a relatively earlier age compared with boys. A girl may undergo physical changes as early as ten years old, which is a sign that her reproductive organs are also maturing.
One unique change that happens to girls is the menarche, or the first menstrual flow, which is the onset of menstruation. Menstruation is the stage when the ovaries start to develop and release one mature egg every month. You will learn more about this in Lesson 4.
Estrogen is the hormone responsible for the growth and development of secondary sex characteristics in females during puberty. Progesterone, on the other hand, is the hormone responsible for maintaining pregnancy by supporting the uterus, especially during its early stages.
During puberty, there is a noticeable growth spurt and faster weight gain. There are a lot of body changes that girls undergo. The first sign of puberty in girls is the development of breasts or breast buds. These will further become bigger and develop into lactating breasts for the nourishment of the baby after giving birth to a child. There is also observed development of hips. Hips become wider and more rounded in preparation for childbearing.
Like boys, girls may also develop pimples and acne on their faces due to the increased oiliness of the skin and sweating during this stage. Along with this, physical activities may increase sweating that can lead to body odor. Hair also grows in the pubic area and the underarms.
Remember
Puberty helps prepare the body for sexual maturity. A person who is sexually mature is physically capable of reproduction.
Have you ever asked why females “bleed” every month? This monthly “bleeding” is referred to as menstruation. This is a normal body process in females. When a girl starts to menstruate, it means that her reproductive system is already mature. This makes a female physically able to conceive or get pregnant. To understand why the menstrual cycle is important in reproduction, you must first understand what the menstrual cycle is. What happens during the menstrual cycle?
The Menstrual Cycle
The menstrual cycle consists of a series of changes that a woman’s body goes through to prepare for pregnancy. The regular cycle commonly lasts for 28 days. It is important to observe if the menstruation cycle is regular or irregular to know if the body is working normally. An irregular menstrual cycle means that the female’s cycle does not follow the standard 28-day cycle.
Menarche
The first menstrual bleeding or menarche may happen as early as 10 years old, although this varies for individuals. Some girls may experience their menarche at a much later age compared with other girls.
Menopause
Menopause or the period when the menstrual cycle stops occurs between the ages of 45 and 55 years old. When a woman undergoes menopause, this means that the ovaries have stopped releasing egg cells and that she is now physically incapable of conception. Menopause happens over the course of several months, and a woman’s body undergoes many changes as menopause occurs.
The Stages of the Menstrual Cycle
The menstrual cycle consists of a series of changes that a woman’s body goes through to prepare for pregnancy. The regular cycle typically lasts for 28 days. It is important to observe if the menstruation cycle is regular or irregular to know if the body is working normally. An irregular menstrual cycle means that the female’s cycle does not follow the standard 28-day cycle.
Menstruation
Menstruation is part of the menstrual cycle and occurs when there is a discharge of blood from the uterus through the vagina. This vaginal discharge includes tissue from the endometrium, blood, and the ovum. This occurs once a month. The first day of menstruation marks day 1 of the menstrual cycle. The menstruation period happens when the uterine lining or endometrium is shed as blood. This is what girls experience during their monthly period, which usually lasts for 3–5 days.
Preparation of the Ovum
After the uterine lining is shed, the preparation of the egg follows. During days 6–13, the uterine lining, which has been shed, repairs itself while the egg in the ovaries matures. The uterine lining begins to thicken to prepare for possible fertilization and pregnancy. Meanwhile, a follicle containing an immature egg begins to grow in the ovaries.
Ovulation
On day 14, the ovary releases a mature egg cell to the uterus. The release of an egg from the ovary is called ovulation. The mature egg is now ready for fertilization and moves into the fallopian tube. The uterus is where the zygote is implanted. This is the reason why during this stage, the uterus continues to thicken in preparation for fertilization and pregnancy. If no fertilization takes place until day 28, the uterine lining will start to break and shed. The moment that menstruation begins also marks the new menstrual cycle.
Proper Hygiene
Observing proper hygiene is key to taking care of the reproductive system. Below are some practices that should be observed, especially when a person has already entered puberty.
Regular Bathing
Take a bath regularly. This will help keep you clean and prevent the buildup of germs and unpleasant odor. By doing so, bacteria will not be attracted to your body, and this can prevent you from acquiring diseases.
Wash the genitals (external reproductive organs) gently. Use mild soap in washing your genitals. Be gentle in washing to avoid getting hurt. Dry them with a clean towel afterward.
Wearing Clean Clothes
Wear clean underwear and change it as often as needed. This is especially true for girls who already menstruate. Changing underwear will prevent you from getting infections caused by the germs that might grow on dirty and moist underwear.
Wear Appropriate Clothing
Wear appropriate clothing. Refrain from wearing tight fitting clothes that can cause pain and irritation in the groin area. As much as possible, avoid borrowing clothes from others as they might have skin diseases that may infect you. For females with menstruation, change your sanitary pads as often as needed. If you feel that your pad is already full, do not hesitate to replace it with a new one. This will prevent you from getting infections.
Other Steps for Proper Reproductive Care
Safety
Aside from observing proper hygiene, one should also be cautious at all times by observing safety. During physical activities, make sure to use protective gear that will protect the reproductive organs. For example, boys should wear a groin protector to prevent getting hurt during a contact sport. Girls who are into sports may wear brassiere with extra support for breast care. There are also some sports that require girls to wear a chest protector to prevent injury to the breasts.
Balanced Diet
Having a balanced diet will keep your body healthy, including your reproductive organs. Adequate nutrition is important for the development of the male and female reproductive system. For females, avoid getting overweight as this may affect the regular menstruation cycle.
Have you seen a baby being born? The first thing a baby does when it comes out from the body of the mother is cry. Its first cry is a sign of its breathing. A baby that is born alive takes its first breath as soon as it is out of the mother’s body. Many animals are born similarly. What are the characteristics of an animal that is born alive?
Among all the different animals in the world, most of the animals born alive are from the group of animals called mammals. There are two main features that are similar to all mammals: first, they are covered with hair or fur; and second, the females produce milk. Almost all mammals are born alive.
Fertilization
Reproduction starts with fertilization. Fertilization can occur outside the mother’s body, known as external fertilization. Fertilization that occurs inside the mother’s body is known as internal fertilization. For animals that give live birth, internal fertilization takes place. This means that the mature egg cell is inside the mother’s body and a sperm cell needs to get inside to reach the egg cell for fertilization to take place.
The embryo produced after internal fertilization stays inside the mother’s body until it is ready to be born. The mother is able to protect the developing embryo inside its body. While inside, the mammal’s embryo is protected by a sac attached to the mother’s body. This sac is called a placenta.
Through the placenta, the mother is able to supply the embryo with food and oxygen from its body. To do that, the mother has to stay healthy and eat extra food, to be able to supply the growing embryo, too.
There are advantages to having the embryo inside the mother. The mother can take care of the developing baby without leaving it unprotected. A mother of a pregnant animal acts in a very protective manner. It can act fiercer than when it is not yet pregnant. It is to make sure that the embryo inside will not be in any harm. The mother can also make sure that the developing embryo is supplied with food, by eating more.
There are also disadvantages in carrying the developing embryo. The mother’s movements can be limited because of the weight of the baby inside it. Also, a mother can carry only a limited number of developing embryos inside its body. The embryo develops fully inside the mother’s body until it is ready to be born. An animal is born when it comes out of the mother’s body.
Gestation
Gestation is another term for pregnancy in animals. Gestation period is the length of time it takes for the embryo to develop inside the mother’s body until it is born. Different animals have different gestation periods. Usually, bigger animals have longer gestation periods than smaller animals. It takes a longer period for a larger embryo to grow, compared to a smaller one. Below is a table that shows the gestation period of some animals.
Mammals That Give Birth to Live Offspring
Some mammals called marsupials carry their still developing embryos in pouches outside their wombs. The embryos are not yet fully developed but they already come out of the mother’s body into a special pouch where the source of milk is located. They stay in the mother’s pouch until they are grown enough to be able to find their own food. Kangaroo and opossum are two examples of animals that are marsupials.
Newborn mammals still need to get their food from their mother’s body. Mothers provide milk for their young until they are able to find their own food. Mammals have mammary glands that produce milk. The young animals can get the milk through the mother’s teats. Different mammals have a varied number of teats. Animals with many teats give birth to more young since they can give milk to more at a time.
Newborn animals take some time before they are ready to move to find their own food and protect themselves. Some can already stand after a few minutes, some in a few hours, and some in a few days. Humans, in comparison, take the longest time before standing on their own.
Non-mammals That Give Birth to Live Offspring
There are some kinds of snakes, sharks, fish, frogs, scorpions, and lizards that can also give live birth. Non-mammal animals that are born alive may develop differently inside the body of their parent. The embryos in most of these animals are in eggs instead of the placenta. The yolk inside the egg provides the embryo with the food that it needs to develop. An anaconda is an example of such an animal. It is a kind of snake that gives live birth. Most kinds of sharks are also born alive. The egg of the embryo hatches inside the body. After a short time, the newly hatched snakes or sharks are born alive.
Seahorse and pipefish have different ways of caring for the developing embryo. The female parent releases the fertilized egg in the pouch in the male parent. The male parent carries the embryo until it is ready to be born. The eggs hatch inside and young seahorse or pipefish are born alive from the father.
Is it true that eating an egg is like eating a whole chicken? Not necessarily. Chickens do come from eggs but the eggs that are usually sold in the market will not develop into chickens. So how does an egg become a chick? There are many animals that hatch from eggs. What are the characteristics of animals that hatch from eggs?
All kinds of birds hatch from eggs. There are many other animals that hatch from eggs too. Most kinds of frogs, lizards, turtles, fish, and insects hatch from eggs. For animals that start their lives as eggs, fertilization can occur internally or externally. Most terrestrial animals undergo internal fertilization. How do animals develop from eggs?
Animals That Lay Eggs but Fertilized Internally
The eggs of birds are fertilized inside the mother’s body. Turtle and snake eggs are also fertilized internally.
Eggs develop inside the female animals when they are ready for reproduction. If fertilization occurs, they will lay fertilized eggs and an embryo will grow inside those eggs. If fertilization did not occur, some animals can still lay their eggs but those eggs will not develop into new animals. The chicken eggs usually sold in markets are unfertilized eggs.
Animals That Lay Eggs but Fertilized Externally
For many amphibious and aquatic animals, external fertilization is common. The females release their eggs in the water. At the same time, males release their sperm cells in the water too. When sperm cells come in contact with the eggs, fertilization occurs and an embryo will form inside the eggs. Sometimes, the word spawning is used to describe this fertilization method in water. Spawn is another way to call the numerous eggs released in water. Hence, we can say that spawning occurs when frogs release their eggs and sperm cells in water.
Types of Eggs of Animals
The types of eggs of animals differ in size, color, texture, hardness, and even shape. But all eggs are designed to protect the developing embryo until it is ready to be hatched. The eggs of birds, turtles, snakes, lizards, insects, and most animals that are terrestrial are enclosed in hard, solid shells.
Eggs Covered With Hard Shell
Eggs of birds are covered with a hard shell. Most turtles, snakes, and lizards have eggshells that are hard but more flexible. Both kinds of eggshells are made mostly from calcium. It is the same material that makes the teeth and bones hard and strong. The eggshell is porous. It has many tiny holes that allow oxygen to enter and carbon dioxide to go out in order for the embryo to breathe, but it is sealed enough to protect the embryo from germs and dirt from the environment. Inside the shell, the growing embryo gets its food mostly from the yolk of the egg.
A nest is where eggs are laid to be kept at a certain temperature (usually warmer than the environment) and protected. Some animals prepare a nest before laying their eggs. Many birds collect leaves, twigs, clay, and other materials to create a nest. Other animals choose a nesting area underground or in areas that would keep the eggs hidden and warm.
Eggs Enclosed in Jelly-like Sacs
Animals that lay eggs in bodies of water have eggs that are enclosed in jelly-like sacs. These sacs keep the eggs sealed even when the water movement is strong. These kinds of eggs are not easily hidden from other animals that may want to eat them. Due to this, animals that spawn release so many eggs at a time. They also spawn in big groups so that their combined eggs will have more chances of survival.
Spawning in big numbers gives a better chance for some eggs to be fertilized, develop, and hatch even if others are eaten by other animals.
Newly Hatched Animals
In many birds, the chicks that hatch from eggs are not yet ready to live on their own. When birds hatch, their wings and feathers are not yet fully developed for flying. They still cannot get their own food. Most birds take care of their young until they are ready to leave the nest and fly.
In many other animals, once they are hatched from eggs, they can already move and find food by themselves. Marine turtles can find their way back to the sea as soon as they hatch. Newly hatched snakes leave the nest and look for food away from the nest. Animals that were spawned in the water may not see their parents again and live on their own.
Compare yourself now to what you were as a baby, what are some changes in you that you have noticed? What other changes do you think will happen until you become an adult? Do other animals undergo change like you? The answer is yes.
Animals undergo changes throughout their life. Some animals change mostly in size, some even in shape and color. Some animals have similarities with their parents even as a young. However, some animals go through several changes before they become similar to their parents. What changes do animals go through in their life cycle?
Life Cycle
Life cycle consists of the different stages in which an animal goes through some changes in its life. There are patterns in life cycles that occur in different animals. Cats and dogs follow a similar pattern but theirs is different from a mosquito life cycle.
When a cat is born, it already has the features of both parents but are not yet fully developed. It is small compared to adults, has less fur and its body parts still has to grow. It will increase in size until it becomes an adult. After two to four years, a cat’s reproductive parts are fully developed. The same body parts can be observed in cats on both stages in their life cycle.
The life cycle of dogs, bears, horses, rabbits and almost all other mammals follow the same pattern as the cat. Other animals such as turtles, lizards and snakes also follow a similar life cycle. After being born or hatched from an egg, the animal will increase in size from young to adult but the body parts of the young resembles the body parts of adults.
They only have two main stages in their life cycle. From the time they are born, they are young. When they grow and their reproductive system is fully developed, they are adults. Animals are considered adults when they are capable of reproduction. As adults, animals will try to look for a mate in order to reproduce. There are no other major changes after their adult stage.
The life span of animals is the average length of time an animal can live. Many animals can reproduce several times within their life span before they grow old and die.
Metamorphosis
Some animals such as mosquitoes, butterflies, dragonflies and frogs, do not only increase in size, their body parts go through changes in their life cycle. Animals that go through distinct changes undergo a process called metamorphosis.
When animals have different stages wherein their body parts are entirely different from their adult stage, they undergo a process called metamorphosis. In insects, metamorphosis can be grouped into two kinds – complete and incomplete.
Complete metamorphosis
Mosquitoes and butterflies have a similar life cycle. The process that they go through is called complete metamorphosis. It means that their body undergoes a larva stage and a pupa stage in their life cycle. Other examples of insects that go through complete metamorphosis are beetles, moths, and flies.
Mosquitoes are hatched from eggs. The mother lays eggs in still or stagnant water. Mosquito eggs are stuck together in groups that resemble rafts. When an egg hatches, a larva emerges and swims in water. A larva is a worm-like stage in many insects. As a larva, it lives in water. It goes to the surface to breathe but it gets its food from the water. It molts several times as a larva. Molting is the shedding of the body cover in animals like insects and spiders. Everytime it molts, it changes in size but it is still in the form of a larva.
The larva changes into a pupa after the last molt. During this stage, it does not eat. It can move a little but it uses most of its energy to change its form. While it is not moving, its body is changing into an adult mosquito inside the pupa. When it is ready, the pupa will split open and an adult mosquito will emerge and fly out of the water surface.
There are different kinds of mosquitoes and their life span varies. Some mosquitoes live only for a few days while some can live up to a month. It is important to note that the egg of some mosquitoes can be in dry places for several months. When it rains and the area becomes flooded, the egg will hatch so the larva can live in the water. Aedes aegypti, the mosquito that carries the Dengue virus is an example of such mosquito.
Butterflies also go through complete metamorphosis but all the stages occur in land. Its eggs are laid on leaves of plants. When an egg hatches, its larva or the caterpillar eats leaves for its nutrition. After it has eaten all it needs, it changes into a pupa, also called a chrysalis, which attaches itself on branches or leaves. The pupa does not eat. Inside the pupa, the butterfly is developing into an adult. An adult butterfly emerges out of the pupa at the final stage of its life cycle.
Incomplete Metamorphosis
Some insects undergo metamorphosis but do not undergo through the larva and pupa stages. This type of metamorphosis is also called incomplete metamorphosis. Grasshoppers, cockroaches, dragonflies and damselflies are examples of insects that undergo incomplete metamorphosis.
A dragonfly lays its eggs in the water. A nymph will hatch from the egg and live in water. A dragonfly nymph do not have wings. It has gills for breathing in the water. It stays at the bottom of ponds or streams where it lives. It feeds on smaller water insects and other small animals that live under water. A dragonfly nymph molts several times while living in water. At the last stage, it will climb out of the water and find a dry surface where it will go through its final molt. After its last molt, an adult dragonfly will emerge and fly.
Two Kinds of Metamorphosis in Insects
Complete egg → larva → pupa → adult
Incomplete egg → nymph → adult
A frog also goes through metamorphosis. Frog eggs are fertilized in water. When an egg hatches, a tadpole will come out. A tadpole has a tail built for swimming and it has gills for breathing in water. After some time in the water, the tadpole develops hind legs first, then the front legs. The next development will be its lungs. The frog will have lungs instead of gills and it will begin to breathe above the water surface. As it becomes an adult, it will lose its tail and begin to spend some time on land.
Flowers come in a variety of colors, sizes, and even smell. Some flowers are bright red like a rose while others are yellow like a sunflower. Some flowers are big like the lily. Others are small like the santan. Flowers also vary in terms of the smell they give off. Some flowers smell sweet while others smell pungent. With all these characteristics in mind, it’s important to note that flowers also differ with their parts. Have you ever wondered what these colorful parts are?
Flowers come in many colors and shapes. Some even have distinct smells. Did you know that flowers are the reproductive organs of plants?
Many flowering plants undergo sexual reproduction, which involves two sets of cells contributing genetic material through contact of reproductive cells. In flowering plants, also called angiosperms, the flower is the reproductive organ which produces the egg and sperm cells (sex cells or gametes).
Parts of a Flower
The flower is the reproductive part of a plant. The parts of the flower are petals, sepals, receptacle, anther, filament, stigma, style and ovary. The function of each flower part could be seen in Image 1. Some flowers have varying numbers of petals, some consist of only male part (stamen) or female part (pistil). However, there are some flowers with both male and female reproductive organs.
Image 1: https://images.app.goo.gl/HDbtEEoqBEeDTkkC6
Flower parts and their functions
Corolla (Petals) - These are structures that are typically colored, which attract pollinators which carry the pollen.
Calyx (Sepals) - Leaf-like structures that enclose the unopened flower. The receptacle is the uppermost part of the stalk to which the different parts of the flowers are attached.
Stamen:
a. Anthers - These are sacs that produce and hold the pollen.
b. Filament - It supports the anthers.
Pistil:
a. Ovary - Inside the ovary may be one or more ovules containing the female egg cells. The ovule becomes the seed, while the ovary becomes the fruit, after fertilization.
b. Style - A tubular structure that connects the ovary to the stigma.
c. Stigma - It is usually a sticky structure which collects the male pollen carried by pollinators during pollination.
Perfect and Imperfect Flowers
Plants may have perfect flowers, where the male and female parts can be found in a single flower. Examples of perfect flowers are lilies, hibiscus (gumamela), and legumes. In imperfect flowers, the male and female reproductive parts are found on separate flowers.
Examples of imperfect flowers include squash, cucumber, and corn.
In the previous lesson, you learned about the different parts of flowers and how these parts contribute to the process of fertilization. Flowering plants undergo different modes of reproduction. Different pollinators aid plant reproduction through sexual means. These pollinators help plants in different ways. How do pollinators help plants?
Pollinators help flowering plants in reproduction. Plants that produce flowers are called angiosperms. All angiosperms have the flowers as reproductive organs and produce seeds that are stored and protected by the fruit.
Pollination
Reproduction in angiosperms starts with pollination, which is when the pollens produced in a flower’s anther come into contact with the stigma of the same or another flower. Self-pollination is when the pollen is transferred to the stigmas of the same flower or the stigma of another flower on the same plant, while cross-pollination occurs on different plants.
The transfer of pollen is possible through agents like air and water, as well as pollinators— animals that facilitate the transfer of pollen from one plant to another. Pollinators include (1) insects such as bees, butterflies, and moths, (2) birds, (3) bats, (4) rodents, and (5) humans, in some cases.
Flowers have different adaptations to attract specific types of pollinators. Some flowers are heavily scented like the durian which attracts bats. Some flowers have a fruity scent that attracts beetles and moths. Other flowers have brightly colored petals that make it easier for pollinators to see.
Fertilization
After the pollen reaches the stigma, it travels through the style to the ovary, which is where fertilization of the female gametes occurs. After fertilization, the ovules develop into seeds, while the ovary becomes the fruit.
The seed is the fertilized egg cell in plants and thus contains the embryo. The three major parts of the seed are the embryo which has all the parts for a new plant, the seed coat which protects the embryo, and the endosperm, the ‘food’ that nourishes the embryo. The seed also contains the cotyledon which is the embryonic leaf found in the embryo which may be the first leaves that will grow out of the seed.
Types of Cotyledons
There are two groups of angiosperms based on the number of cotyledons in the seed. Most angiosperms are dicotyledons (dicots), which have two cotyledons and develop a taproot system and leaves with webbed veins. Monocotyledons (also monocots) have only one cotyledon and develop a fibrous root system, as well as leaves with parallel venation. Flowers of monocots have petals in three’s or multiples of three, while flowers of dicots have petals in five’s or multiples of five. The vascular tissues in the stems of monocots are randomly arranged, while those in dicots are in an organized fashion.
The Seed
The seed of flowering plants may be enclosed in a fleshy fruit, such as in mangoes, oranges, bananas, and peaches, or may be enclosed in dry fruits, such as in the case of beans and peas.
The seeds are then dispersed by different agents including air, gravity, and animals. Some plants have seeds that have hook-like features. These hooks attach to an animals’ coat and get carried around. Some plants also have winged seeds. These are carried and dispersed by wind. The farther it can be blown by the wind, the farther it will be dispersed. Seeds of most tree species and those with edible fruits are mainly dispersed through ingestion by animals and humans, a process that relocates the seeds and allows them to grow in a new environment. When growth conditions are right, the seed starts to absorb water and germination, the growth of a new plant from a seed, commences.
As you have learned in the previous lessons, angiosperms rely on their flowers so that they can reproduce. However, take note that not all plants are angiosperms. Some plants do not have flowers and instead have other parts that they use for reproduction. Examples of non-flowering plants are pine trees, ferns, mosses, and liverworts. These nonflowering plants use different means to reproduce and survive. Do you ever wonder how nonflowering plants reproduce?
Not all plants can produce flowers. Regardless, these nonflowering plants can still reproduce. Non-flowering plants reproduce either through seeds or through spores. Gymnosperms, which include the pines, firs, and ginkgos reproduce via seeds, while ferns and mosses reproduce by spore formation.
Reproduction in Gymnosperms
In contrast to angiosperms, gymnosperms, from the Greek words ‘gymnos’ meaning naked and ‘sperma’ meaning seed, are vascular plants that do not produce flowers and whose seeds are not enclosed in a fruit. A subclass under gymnosperms is made up of conifers, which include the pines.
Conifers are a group of woody plants mostly with long, thin and needle-like leaves, although some may vary. The reproductive organs are called cones, which bear the seeds. The larger female cones bear the ova, while the smaller male cones contain the pollen. In pines, the seeds (or ovules, if unfertilized) are found in the scales of the cones. The cones also have a stem known as the peduncle, which extends through the entire length of the cone as the rachis.
Male cones have structures called microsporangia (sing. microsporangium) that produce the pollen, which are then carried by the wind to female cones. Pollens pass through the micropyle, a tiny opening in the ovule. When pollination in the ovule is successful, fertilization of the female gametes follows, and the seed is formed. The seed, which typically remains dormant for several years, remains attached to the scales of the female cone. Seeds may be dispersed by animals, usually birds, or by shedding of the scales. On the other hand, a male cone typically disintegrates shortly after pollination.
Most conifers are monoecious, which means that a single plant would have male and female cones and therefore produce both pollen and ovules. However, some species may be dioecious, which produce pollens and ovule in separate individuals.
Cycads are another group of gymnosperms with only a few surviving species. Cycads typically have a palm-like structure and are grown as ornamental plants in some tropical areas. Their life cycle is similar to conifers. However, cycads retained the free-swimming sperm, a primitive feature not found in conifers. To compensate for this, cycads can attract insect pollinators.
Reproduction in Ferns
Ferns are vascular plants that reproduce through spores and do not produce flowers or seeds. The leaves of ferns are megaphyll type, those having more than one vein, like those of angiosperms and gymnosperms. The leaves are often referred to as fronds.
There are two types of fronds. Trophophylls are vegetative leaves that do not produce spores and function only for photosynthesis. Sporophylls are fertile leaves where spores are produced. The spores are housed in a structure called sporangium (pl. sporangia), which forms visible aggregates known as sori (sing. sorus) on the underside of the sporophyll.
Spore-producing organisms have two alternating life stages. The sporophyte stage, which is the dominant life phase in ferns, is the asexual stage which produces the spores from which the gametophyte arises. Gametophyte is the phase that produces both male and female gametes which for sexual reproduction.
Once released from the sporangium (sac containing the spores), a spore develops into a gametophyte and produces the gametes. The sperm cells are released to fertilize the egg cells under moist conditions, and an embryo is developed. The embryo eventually outgrows the gametophyte and becomes a sporophyte.
Reproduction in Mosses
Another group of spore-forming plants is mosses—small, seedless, non-vascular plants that produce no flowers. Unlike in ferns, however, the dominant phase in the life of mosses is the gametophyte stage. Being non-vascular, mosses require sufficient moisture in the environment for its growth. Mosses do not have true roots and instead have rhizoids, root-like structures found in non-vascular plants.
Mosses start as spores that grow into a gametophyte. The sperm cells, which are motile because of two flagella, swim towards the egg cells. Fertilization follows to form a zygote. The zygote then develops into a sporophyte, which will be producing spores.
Plants can also reproduce without the fertilization of gametes. They do this through asexual reproduction. There are many different mechanisms by which plants can do this. For example, some plants can form new individuals from cut stems or roots. Similarly, a potato from your kitchen can grow into a new plant? What are the other ways by which plants can reproduce?
A potato can grow into a new plant through its “eyes.” You will learn how other plants have different ways to reproduce asexually.
Methods of Asexual Reproduction
Asexual reproduction is when an organism propagates itself without the production and fusion of gametes. Natural asexual reproduction results in new individuals that are identical to the parent plant. Asexual reproduction may be through apomixis or vegetative reproduction.
Apomixis
Apomixis is where seeds are produced without the fertilization of gametes. Dandelion and some citrus species undergo apomixis.
Vegetative Reproduction
Another method of asexual reproduction is vegetative reproduction. In vegetative reproduction, a plant part, typically the stem and the roots, and sometimes the leaves, is structurally modified to give rise to new individuals.
Structural Modifications in Vegetative Reproduction
Rhizome
A rhizome is a modified horizontal underground stem that grows shoots and roots systems of a new plant. It is a fleshy, non-green underground stem. Iris, gingers, and bamboo are examples of plants that grow rhizomes.
Stolons
Stolons (also called runners) are horizontal stems that grow at the soil surface and form new plants. Cynodon dactylon or Bermuda grass, as well as strawberry, extend through stolons.
Tubers
Potatoes have stem tubers, which are modified stems that function for storage. Tubers are the swollen tip of an underground lateral stem(stolon). It is covered by a corky skin with a number of small depressions called ‘eyes’. These ‘eyes’ of potatoes grow new stems and roots, through which a new plant can be produced.
Bulbs
Bulbs like those in onions (Allium cepa), garlic (Allium sativum) and tulips (Tulipa sp.) reproduce by dividing their underground bulbs into more bulbs. Corms are similar to bulbs, however, they are primarily a swollen stem modified into a storage tissue. Examples of corm include gladiolus and crocus. Some plants, such as in Kalanchoe pinnata (Tag. Kataka-taka) grow new leaves on the entire edges of its leaves.
Artificial Methods of Asexual Reproduction
Several methods of asexual reproduction have also been developed to give rise to new plants.
Grafting
Grafting, which is widely used in producing new varieties of roses and grapes, involves the holding together and connecting two plant parts: a rooted plant and the topmost part of the stem of another plant. The stem to be attached, called the scion, is allowed to fuse with the rooted plant called the stock. This method is used to combine favorable stem characteristics of the scion and root characteristics of the stock.
Cutting
Cutting involves planting stem cuttings with nodes and internodes in healthy soil, or sometimes, even just in water, as in the case of African daisy. On the other hand, layering is done by planting young stems to the soil while they are still attached to the plant. Bougainvillea and Jasmine can be propagated this way.
Have you ever been to Manila Bay? If so, did you watch its breathtaking sunset? If not, what information do you know about the bay? Manila bay is considered one of the best natural harbors in the world. Aside from its economic and historical significance, the bay is also ecologically important. Manila bay is a semi-enclosed estuary home to various species of birds, fishes, invertebrates, and mangroves. How do these organisms interact with each other in this type of ecosystem? How do these organisms interact with the nonliving components of the ecosystem?
Just like forests and deserts, rivers and oceans have their own set of living things. The surrounding area or environment in each area also varies. An area where living things interact with each other, and with the nonliving things in their surroundings is called an ecosystem. An ecosystem is composed of two broad groups namely biotic and abiotic factors.
Biotic and Abiotic Factors of an Ecosystem
Biotic Factors
Living things or organisms in an ecosystem are collectively called biotic factors. Animals such as worms, ants, birds, and fishes are examples of biotic factors. Different kinds of plants are also considered biotic factors. Plants, animals, and other organisms interact with each other in an environment.
Abiotic Factors
Abiotic factors need other elements to live in a particular ecosystem. Nonliving elements found in the environment where the biotic factors live are collectively called abiotic factors. Sunlight, water, soil, and gases that make up the atmosphere are abiotic factors in an ecosystem. These abiotic factors interact with living things. Biotic factors need abiotic factors to survive. Think of a plant as an example of a biotic factor. It needs abiotic factors such as sunlight, water, and soil to grow and survive.
Biotic and abiotic factors affect each other in their interactions. Plants anchored in soil help keep the soil in place and get its water and nutrients from the soil. Waste products of animals allow nutrients to get incorporated back into the soil. The amount of nutrients in the soil affects the growth of plants. Abiotic factors can also affect each other. For instance, soil can be more exposed to the sun’s heat and light. This will make water from the soil easily evaporate, which causes soil to dry up.
Estuary Food Chain
Roughly 70% percent of the surface of our planet is water. With this large area of water, aquatic ecosystems are greater in terms of the area covered. Aquatic ecosystems are divided into freshwater and marine ecosystems. A special type of aquatic ecosystem where freshwater and marine water meet is called an estuary. An estuary is a place where water from a river or a stream reaches and meets with the water from an ocean. It is also called brackish water. An estuary is further characterized by the following characteristics:
a shallow depth of water
a distinct environment and vegetation
a varying salt concentration that is due to the changes in tides and flowing water (salt concentration in estuaries is lower than that of oceans but higher than rivers or streams)
a nutrient-rich ecosystem
a low depth of water which allows the sun to penetrate easily
Because of the abundance of nutrients and penetration of sunlight, plants and other producers in estuaries can make food for other organisms. Consequently, different plants and animals can be found in the estuary. Plants and animals adjust with the changing salt concentration and water flow of estuaries. Examples of plants that have adjusted with the salt concentration of estuaries are salt grasses and mangroves.
Estuaries are home to a wide range of organisms that interact through their feeding relationships. Plants and phytoplanktons are the producers in an estuary. Phytoplanktons are tiny organisms that float on the water surface. Like plants, phytoplanktons can use the sun’s energy and make their own food through photosynthesis. The food chain and food web begins with those producers in the estuary. For instance, a phytoplanktons can be eaten by a consumer such as zooplankton. Zooplanktons, which are mostly tiny animals, can be eaten by a crayfish, which a fish can then eat. When the fish dies, it can be decomposed by bacteria and fungi.
Levels of Interaction in the Estuary Food Web
In any ecosystem, an organism may eat different kinds of food. Ducks in estuaries, for example, can eat smaller animals, plants, and other organisms that they can filter from the mud. Organisms can be eaten by different organisms. Clams may be eaten by fish and birds, for instance. In an estuary, many food chains are interconnected in a food web.
Some snails, fish, and birds feed on aquatic plants and phytoplanktons. Zooplanktons, shrimps, some worms, and many kinds of shelled animals feed on phytoplanktons. These organisms are the primary consumers in the estuary community. Primary consumers are those that feed on producers.
Primary consumers serve as food for larger animals in an estuary. The consumers that feed on primary consumers are described as secondary consumers. Many kinds of migratory birds, fish, and shelled animals eat smaller primary consumers. These secondary consumers can either be carnivores or omnivores, but none are herbivores or purely plant-eaters.
Tertiary consumers are animals that feed on secondary consumers. These animals are mostly apex predators. Apex predators are organisms that are normally not considered food for other predators. Large carnivores and omnivores are usually apex predators in estuaries. Eagles, large fish, seals, and crocodiles can be the tertiary consumers in estuaries in different parts of the world.
The estuary will not have its cycle of nutrients without decomposers. Decomposers in an estuary include small detritivores such as crabs, shrimp, fish, worms, shelled animals, and insects. They feed on portions of decaying or waste matter from other plants and animals or materials that they can filter from the water and the mud. The feeding habits of detritivores help bacteria and fungi break down materials into nutrients that can be returned to the soil, water, and air.
In the Philippines, the most common example of an estuary is the mangrove estuary. A mangrove is commonly known as bakawan in the Philippines. Mangrove estuaries are usually found in Mindanao and Palawan. A mangrove is a small tree that grows in estuaries. Mangroves use their complex root system to adapt to the changing salt concentrations and water flow of estuaries. They also serve as shelter and breeding sites for other organisms.
Have you walked along the shoreline of a sandy beach? Did you also notice those tiny holes scattered along the beach? If yes, then you have probably tried poking those holes and wondered what is inside. If you distance yourself and wait for some time, you might be able to see little crabs coming out of those holes. Aside from crabs, a lot of unique creatures like barnacles, limpets, and sand hoppers can be found living on the beach shore. How do these organisms interact in this kind of environment?
From estuaries, where freshwater meets marine water, come the oceans. An ocean is so vast that they serve as a home for different kinds of organisms. It is divided into three major zones, namely the (1) intertidal zone, (2) neritic zone; and (3) oceanic zone.
Zones of the Ocean
The intertidal and neritic zones are the parts of the ocean that are more exposed to sunlight. Thus, producers in these zones are able to grow and provide food for other organisms. The oceanic zone is further subdivided into bathyal and abyssal zones. There are more consumers than producers in the oceanic zone because of light penetration. In the bathyal zone, the light coming from the sun penetrates the zone partially. On the other hand, light cannot penetrate the water in the abyssal zone. Organisms in this zone could have other means of harnessing energy. At this point in time, there are only a few known organisms that thrive in the abyssal zone.
Among the different zones of the ocean, intertidal zones are of immediate concern. An intertidal zone is an area where land meets the ocean. It is also known as the littoral zone. It is basically the seashore where tides mark the sand or land. It is the shallowest part of the ocean and is also subjected to the changing tides of the ocean. Most of the intertidal zone is submerged in water during high tide and partially submerged during low tide. It is either sandy or rocky. In rocky intertidal areas, the part where the tide creates a splash with the rocks is called the spray zone.
Intertidal zones can be divided into three subzones, namely the (1) high intertidal, (2) middle intertidal, and (3) lower intertidal. Most of the time, the high intertidal zone is exposed to sunlight. It is only submerged in water during high tide. It is exposed out of the water for most of the time. The middle intertidal zone, on the other hand, is submerged in the water for a longer period of time than that of the high intertidal zone. It is commonly exposed during low tide. The area which is generally submerged in water is the lower intertidal zone. It is only exposed during the lowest tide of the year.
Due to different subzones, the intertidal zone serves as a home for different kinds of organisms. These organisms have adapted adaptations for the changing water level, waves, moisture, and temperature brought by the changes in tides or waves.
Animals such as anemones, limpets, mussels, and barnacles have shells to adapt to this environment. They attach themselves to rocks to withstand the changing tides of the zone. Crabs, on the other hand, burrow themselves into the sand. Some hide under the rocks.
Producers like algae, seaweeds, seagrasses, and sea lettuce also attach themselves to rocks in order to fight the changing tides.
These producers serve as food for the consumers to survive in surface water. Phytoplankton can also be observed in intertidal zones. Other organisms that thrive in the intertidal zone include mussels, sea urchins, sea stars, snails, sponges, sea anemones, and kelps.
In many rocky shores, some parts are lower than others, or some rocks are hollowed out because of the constant action of water. When the water recedes during low tides, some seawater is trapped in those areas that we call tide pools. Tide pools are natural pools of seawater commonly found in intertidal zones with rocky shores.
Being surrounded by seas, the Philippine islands are bounded by intertidal zones. A famous place for estuaries and also intertidal zones is the Palawan. The complex diversity of organisms found in intertidal zones makes up the rich interactions of organisms.
Interactions in the Intertidal Zone Community
Phytoplanktons and zooplanktons are carried by the rising tides and ocean waves. Many primary consumers in the intertidal community are filter-feeders. Shelled animals like barnacles, limpets, shrimps, mussels, and clams are primary consumers. They take in seawater and filter the phytoplanktons, zooplanktons, and other materials that are carried by the water.
Some animals that are secondary consumers are more active hunters and feeders like whelks, sea anemones, starfish, and crabs. Those animals have special body parts that allow them to hunt or trap, catch, and eat their prey. Whelks, for instance, are small carnivorous sea snails. They have drill-like tongues that bore holes on shells to reach the soft body parts of shelled animals. Some, like sea anemones, have tentacles that can sting and paralyze their prey. Even though sea anemones mostly stay in one place, they can still catch small animals for food.
Intertidal zones are feeding areas for some fish and predatory birds and they are often at the top of the food chain. Many animals like the filter feeders are also detritivores that help cycle the nutrients not only within the intertidal ecosystem but also to the larger body of water they are in.
Filipino families love to celebrate special occasions by going to a public beach. Does your family also do this? If yes, what did you notice about public beaches? Aside from the huge number of people getting a dip, you might have observed improperly disposed trash left on sand or floating on water. If this irresponsible behavior continues, what do you think will happen to the beach in the future? How will this action impact the beach organisms and its ecosystem?
Importance of Estuaries and Intertidal Zones to Ecosystems
Estuaries and intertidal zones are home for a variety of organisms. They serve as shelters for different animals such as small shelled animals, birds, fishes, and even large animals such as crocodiles. These ecosystems also serve as breeding areas or nursery for different animals like fishes and crocodiles. Its nutrient-rich nature and protected environment makes estuaries ideal for organisms to breed, make nests, and allow their young to grow before returning to the open ocean.
Estuaries and intertidal zones are considered as two of the most highly productive ecosystems. For animals such as migratory birds, fishes, and other marine organisms, these areas function as feeding sites. With food chains and food webs in mind, small organisms living in these ecosystems serve as food for the mostly bigger organisms. Many kinds ofbirds visit estuaries and intertidal zones in a regular feeding pattern. The small organisms in these ecosystems are also eaten by larger sea creatures in the open seas.
Estuaries contribute also to a cleaner environment. They act as natural filters of the pollutants of the sea. Plants in these areas absorb flood waters before entering the marine waters. The root system of estuarine plants like mangroves and other saltwater plants and trees controls erosion thus limiting the soil and sediments that are carried away to the open sea.
Importance of Estuaries and Intertidal Zones to People
With their amazing scenery and surroundings, these areas also serve as places for recreation. They are must-see tourist spots in archipelagic countries. Beach resorts are built at intertidal zones.
Numerous tide pools that form along the rocky shores in Philippine islands are sought-after tourist destinations. The Dinagat Islands, a province just South of Leyte and North of Surigao, have diverse rock formations interspersed with tide pools in its beaches. A tidal pool in Pangabangan, Libho, Dinagat Islands, is semi-surrounded with larger rocks that makes it look more like a blue lagoon, as most tourists would describe it.
Biri islands, part of the marine-protected areas in the province of Samar, are known for its tidal pools and seawater falls, which are the natural features that are due to its rocky shores.
The Magpupungko tidal pool in Siargao is another famous tourist destination. The tidal pool that can be seen during low tides, is famous for its clear water that is in different hues of blue. These are but some examples of tide pools that are gradually being developed into tourist areas.
Aside from its importance as a tourist destination, tide pools also hold importance in aquaculture. Milkfish, locally known as bangus, enter the tide pools from the sea as juveniles. New stock of economically important fish such as milkfish, is important in the fisheries and aquaculture industries. Collection of sea urchins, seaweed, and shelled animals that abound in tide pools, are part of the livelihood of many coastal communities.
Boating, fishing, and nature expeditions abound at estuaries. They contribute to the economy not only through recreation but also in fisheries. Many of the fish and shelled animals that people use as food are either bred, farmed, or caught in these ecosystems. Philippine estuaries with mangroves as its main vegetation have high ecological importance resulting in high economic importance. Many animals in the brackish waters are dependent on the mangroves for food and shelter. Humans also use mangroves for fuel and construction material, and harvest areas of different animals that humans consume as food.
For humans, aside from direct resources for food and recreation, they are also being utilized by scholars as a place for education and research.
Impacts of Human Activities to Estuaries and Intertidal Zones
Places with estuaries and around the intertidal zones are being populated with humans. This results in an increase in human activities which poses a threat to these ecosystems.
Humans are apex consumers. With increasing human population, the natural order in these ecosystems are being affected. Humans have technologies or tools for getting more organisms for food. This affects the food web of both estuaries and intertidal zones. The mangroves, which are important features of many Philippine estuaries, are also being harvested as fuel and construction material. The mangroves are also sacrificed in the construction of fish pens or for shrimp culture.
Humans have a lot of activities that impact the abiotic factors in these ecosystems. Improper waste disposal, land development, establishment of recreational areas, destructive fishing, and other human activities done in the land surrounding these aquatic ecosystems affects the quality of water. Poor water quality negatively impacts the health of organisms living in these environments.
Pollutants are carried by the flow of water from man-made structures to streams and rivers down to the marine waters. Pollutants in estuaries and intertidal zones include oil and sewage spills, toxic chemical substances, and waste materials. These pollutants may reduce the diversity of organisms that live in these areas. In some cases, estuaries and intertidal zones are being developed into recreational and residential areas which results in destruction of natural habitat in these areas.
Natural events such as typhoons, landslides and tsunamis also pose threats in these areas. Tsunamis are large ocean waves resulting from underwater earthquakes. The impacts of big waves can destroy shelters and have other damaging effects in these ecosystems. Wind and water from typhoons can cause direct damages to both biotic and abiotic factors in estuaries and coastal areas. Sediments from water flow and landslides can carry huge amounts of pollutants from human settlements down to estuaries and intertidal zones.
Conservation of Estuaries and Intertidal Zones
The importance of estuaries and intertidal zones to natural and man-made ecosystems are established. But because of the different human activities and natural calamities, there are only a few estuaries and intertidal zones which are considered safe and free of pollutants. Some estuaries were even completely detached from other aquatic ecosystems, when they were converted to recreational and residential areas. The current situation of these ecosystems show that there is a need to repair, protect, and preserve them. In other words, there is a need for conservation of these ecosystems.
Conservation involves actions that would raise awareness about the state of ecosystems; repair, rehabilitate, and reduce damages; and preserve the natural state of those ecosystems. Small activities such as proper waste segregation and disposal, use of household products with chemicals which are not harmful, using less electricity, and conserving water at home will have positive impacts to these aquatic ecosystems.
In the Philippines, local government units and communities that have become aware of the state of their estuaries and intertidal zones, are taking steps towards conservation of these ecosystems. Conservation-related activities include monitoring these water ecosystems against illegal and damaging activities caused by human activities.
Many estuaries and intertidal zones are already declared as conservation areas, and there are rules in place to restrict damaging activities in those. Those areas are open only for researchers who study the water ecosystem. They eventually give recommendations on how to best protect and conserve these areas. Rehabilitation of endangered and damaged water ecosystems are also being done to save them.
Ecotourism
Ecotourism is becoming a popular form of economic activity that also serves as a good way in increasing the awareness of people about the importance of estuaries and intertidal zones. It is a type of tourism in which a particular place is being transformed into a tourist spot without damaging the natural arrangement of the place. It is a way of promoting a place while profiting from it. If properly implemented, this kind of tourism benefits both the community and the ecosystem in the area.
Ecotourism is an effective way to increase awareness of the local community where estuaries and intertidal zones are located about the importance of these ecosystems. In this way, the local community also gains profit making their economy grow. Part of the profit may then be used to rehabilitate the area or to protect them against potential threats.