Primitive Chordates = Animals such as sea squirts resemble ancient animals that modern chordates may have evolved from. The sea squirt larva has chordate structures, although the adults do not.
Lampreys = These animals are the most primitive of the vertebrates. They have a true backbone which is made of cartilage. These serious pests use round jawless mouths to catch bony fish. After which they suck the blood and other soft tissues out of the animals.
Sharks and Rays = These mostly marine vertebrates have a cartiliginous skeleton and un covered gills. They are able to regrow their teeth made from skin tissues. Rays are like sharks, but they have larger pectoral fins so that they can swim.
Bony Fishes = These vertebrates are mostly covered with scales. They use gills to breath and have air-bladders that adjusts the animals buoyancy to pressure at different depths.
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