Animalia and its Seven Phylum


    The Animal Kingdom contains more than two million known species. 

    The Animal Kingdom contains these seven Phyla: Porifera, Cnidaria, Platyhelminthes, Annelida, Mollusca, Arthropoda, and Chordata.

    The bodies of animals are made up of differentiated tissues to perform an equally specialized task, sometimes in to or three levels of differentiation (excluding sponges).

    Most animals also reproduce sexually and are diploid, meaning they contain two copies of their genetic material.

    Animals also lack cell walls, which are the primary structure of organisms in the phyla Plantae.

    Mollusks, Crustaceans, and Nematodes make up most of all organisms, while Chordata, both the skeletal structure and the phyla that we are put in as humans take up a small fraction of organisms, in comparison. 

    The more common name for the Porifera is the Sponge. Porifera are marine animals, although with an exception of a freshwater one. They are found in every known part of the ocean, and directly interact with many other animals in the ocean. One of these interactions is where a sponge grows on the shell of a snail that is being used by a hermit crab, and then will move around as the hermit crab does.

    In general, sponges eat by filtering out bacteria out of the water around it, and are even capable of regulating the flow of water around it. There is an exception, however, where some sponges can capture crustaceans as they brush around it. The cells gradually draw the crustaceans in, and the cells digest it from the outside.

    Porifera are both female and male. During different parts of a personal reproductive cycle, they produce either sperm or eggs. By releasing their sperm into the water, it may get carried and when it comes in contact with another Porifera of the same species, it may fertilize any eggs it may currently have. This does not apply to all porifera, as some reproduce asexually. Some porifera include the sea anemonae and the sea sponge.
    Cnidarians are all very different, but a few key traits lead us to believe that they all have a common ancestor, and therefore belong in a group together.

    Cnidarians all have some physical form that is similar. They are tall and round, with medusae- like tendrils floating around them. They are especially notable that they are the most feathery of aquatic animals, although these feathery parts are nothing like those in birds.

    The trait that most people are familiar with and that makes scientists believe that they are all related is the fact that they all have stinging cells, which is their primary defense mechanism.

Coral, Anemones, box jellies, and jellyfish are all apart of this group.
    Platyhelminthes are better known as Flatworms. Flatworms are symmetrical and are made up of three layers of cells.

    Other than a gut, these organisms have no cavities. Because of this features, these organisms must depend on diffusion, a process of the gradual spreading out of matter, which makes it so they must retain their flat shape.

    Flatworms are internal parasites, or organisms that survive by feeding on matter inside another organism's organs. 

     It is believed that most flatworms descend from the same ancestors as many mollusks and earthworms, while the rest seemed to evolve from the more basic roots of animals.

    Flukes, planarians, and marine flatworms are all Platyhelminthes. 
    Annelida are segmented worms, including earthworms, leeches, and marine worms. We know of about 9000 different Annelida. Annelida do not include the smooth worms that come to mind when we think of them, but also bristled ones, too. Some Annelida include bristleworms, earthworms, and leeches.
    Mollusca has at least 50,000 species, although it is estimated that there are more than 200,000, such as clams, oysters, snails, and octopuses.

    Mollusca are one of the organisms that have an exoskeleton, which is made of chitin, such as the shells of snails. Although they are very diverse in shape, and have, for example, from one foot on a snail to 8 feet on an octopus, they all seem to retain some patters, such as all seem to have an area for their head distinctly separated from the area with their feet.

    Mollusca are also major parts of almost every ecosystem, for example in some cases up to 3,000 species have been found in one coral reef. One of the reasons for this is that they have highly variable diets. 
    Arthropoda take up 3/4 of all living and fossilized organisms. 

    Arthropods are all covered in an exoskeleton made of chitin. Chitin is what makes organisms in this phylum so crunchy- such as ants, crabs, crayfish, and lobster.

    The phylum gets its name because of the way the chitin joints the appendages together.
    The Chordata phylum is the phylum which we are the most physically familiar with, as we ourselves are Chordata. The most distinguishing feature of a Chordata is that it has a bundle of nerves and cartilage supporting these nerves all along the back, also known as the spine.

    Chordata also oftentimes have similar bone structures, and even have a few odd structures that are similar, such as slits that connect the throat to the neck, such as in humans where you end up with a rolling pattern, as we do not use these slits as gills.