Question

explain the main characteristics of the major chordate classes

Answer 1

The chordate classes and their characteristics are :

1)agnatha: jawless fish. The oldest known vertebrate .Two primary types in this:hagfish and lampreys. Hagfishes are specialized scavengers while lampreys are parasites that use suction to attach itself to other fish in order to feed.

2)chondrichthyes:cartilage fish,made up of cartilage entirely. Mouth lies underside of head with numerous teeth. They have asymmetrical upward -pointing tails and no swim or lung-bladder.

Eg: sharks, rays

3)osteichthyes:bony fish.They have bones instead of cartilage. They also have swim-bladder which is a gas-filled sac that keeps them buoyant .They also have operculum,which is a bony flap over gills to protect their gills. Eg:catfish,tuna

4)amphibia: spend life both on land and in water. Can breathe through skin .These are cold blooded animals. Eg:frogs,salamanders.

5)reptilia:They lay shelled eggs. They use tongue to smell and are cold blooded. Cannot breathe through skin. They have scaly,water-resistant skin.Four-limbed.eg:sea-turtles,snakes

6)aves: only class in chordata with powered flight, but not a necessity. Distinguished features are feathers,hollow bones to make them lighter, and one-way breathing system .

7)mammalia: Warm blooded animals that have hair and produce milk to nourish their younger ones. They have four limbs and also they have three earbones unlike other groups. They have larger brains. Eg: monkeys,humans.