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Chordata (45,000 Species)
Chordata (45,000 Species)
Chordate characteristics
Chordate characteristics
-Bilaterally symmetrical
-Deuterostomates
-At one point in their lives they have each of these 4 things
-Notochord
-Pharyngeal slits
-Dorsal tubular nerve cord
-Postanal tail
-Presence of endostyle or thyroid gland
-Complete digestive tract
-Ventral, contractile blood vessel (heart)
Fish
Fish
Fish is an informal name for three classes of vertebrates
Fish is an informal name for three classes of vertebrates
The three classes of fish are
The three classes of fish are
Agnatha (Jawless Fish)
Agnatha (Jawless Fish)
Chondrichthyes (Cartilaginous Fish)
Chondrichthyes (Cartilaginous Fish)
Osteichthyes (Bony Fish)
Osteichthyes (Bony Fish)
Class Agnatha
Class Agnatha
-Have no Jaw
-The Jawless fish are of the most primitive fish living today
-Because they have no jaw they feed by suction
-They have a round mouth with rows of teeth
Lampreys
Lampreys
-Mostly a freshwater fish. Breed in lakes and rivers and sometimes move to the sea as adults
-Attach to other animals and suck their blood
Class Chondrichthyes
Class Chondrichthyes
-Cartilaginous fishes
-Includes the sharks, rays, skates, and ratfishes
-Have a cartilage skeleton
-Placoid scales- rough sand paper like skin because placoid scales are similar to teeth.
-Point backwards
-Paired lateral fins
Order of Sharks
Order of Sharks
-Caudal fin- pointing up and down
-Heterocercal- Upper lobe is longer than the lower lobe
-Two dorsal fins
-Paired pectoral fins
-Five to seven gill slits
-Replaces teeth that are lost
-Can sense electricity
-Can sense vibrations in the water
The worlds largest fish is a whale shark
A whale shark can grow up to 50ft. It has no teeth and eats plankton
-Sharks are not very dangerous to humans
-Only about 5 deaths world wide happen because of sharks
-Almost 500,000 people in the United States a year go to the emergency room because of dog bites
The shark that is the most dangerous to humans is the great white shark and the bull shark has the most dangerous human shark attacks
Order Batoidea (Rays and Skates)
Order Batoidea (Rays and Skates)
-Rays and skates are dorsally and ventrally flattened
-Rays have live birth
-Skates lay eggs
-Skates have more of a triangle shaped front end
Bat Rays
Class Osteichthyes
Class Osteichthyes
The Bony Fish
-23,000 species
-96% of all fish and about half of all vertebrates
Characteristics of Osteichthyes
Characteristics of Osteichthyes
-Cycloid scales- smooth, made of bone but have skin over them
-Ctenoid scales- have tiny spins on their exposed boarder
-Operculum or Gill Cover- a flap of bony plates that protects the gills
-Usually homocercal- The lobes of the tail fin are the same size
-Fin rays- spins that support the fin
-Terminal mouth- Mouth at the end of the body unlike the ventral mouth of the chondrichthyes
-Swim Bladder- Gas filled sac just above the stomach to adjust buoyancy
-Needed since bones are heavier than cartilage
Watch this video on how gills work
Mud Skipper
Watch this video about the African Lungfish
The Transition to land
The Transition to land
In the evolutionary history of animals, fish evolved into amphibians. The bony fish have a swim bladder that helps them with buoyancy. In many species the swim bladder can be used as an auxiliary lung. For example, gold fish and betta fish can gulp air from above the water, sending it to their gills. This is why you can keep goldfish in a bowl that has little oxygen.
Lobe fin fish and lungfish have evolved to walk on land and breath air. These fish are the ancestors of the transitional species that came to land becoming the amphibians.
Tiktaalik was a great fossil discovery that helped scientist developed a better picture of the history of amphibians.
Watch this video on Salamanderfish. Create a box in your sketchbook, title it "Salamanderfish" and take notes, write down interesting things that you learn from the video and include an image in your sketchbook.
Watch this important video up until 3:18. You do not have to watch the second half of the video unless you want to.
This is a very interesting but optional video.
Class Amphibians
Class Amphibians
(Two lives)
-Amphibians were the first fully terrestrial vertebrates
-Amphibians have two lives
-They are born underwater and have gills
-Then as they grow they go through a metamorphosis growing lungs and become terrestrial
-Have aquatic eggs that must be laid underwater
-Most need to stay moist to help them breath through their skin
Watch this video on the class Amphibia. Create a box in your sketchbook, title it "The Class Amphibia" and take notes, write down interesting things that you learn from the video and include an image in your sketchbook. Make sure you understand the characteristics of amphibians and can tell the differences between their orders.
Order Caudata (Tail Bearer)
Order Caudata (Tail Bearer)
-About 400 species
-They are the Salamanders
-Have the ability to regenerate any body part or organ
Salamanders
Salamander Larvae
Order Anura (4,000 species)
Order Anura (4,000 species)
-Tailless
-Elongated hindlimbs modified for jumping
-Frogs and toads
Frogs
This is an optional video
Frog Larvae (Tadpole)
Frog Metamorphosis
This is an optional video about frog hearing
Toads
-Live out or away from the water as adults
-Have drier skin
Order Gymnophiona (220 species)
Order Gymnophiona (220 species)
-The Caecelians
-Legless amphibians
-Highly adapted for burrowing
This is an optional but interesting video about when amphibians ruled the earth
Optional! This is a slow and probably boring documentary about the life of tiger salamanders, but I find it to be enjoyable :)
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