7 Deadly Classes of Vertebrates

Hanna Hetrick

Agnatha

The oldest class of vertebrates

Includes lampreys and hagfish

Chondrichthyes

Otherwise known as the cartilaginous fish

Have skeleton made of cartilage

Includes sharks, rays, and chimeras

Osteichthyes

Otherwise known as the “Bony Fish”

Skeletons are made of bone

Most diverse group

Includes Ray-Finned Fish

Amphibia

First vertebrates to live in land and water

Reproduce in water or on moist land

Include salamanders, frogs, caecilians

Reptilia

Able to retain moisture, meaning they can live exclusively on land

Produce eggs that do not develop in water

Include snakes, lizards, crocodiles, alligators, and turtles.

Aves

Otherwise known as birds

Distinguished by the presence of feathers

Mammalia

Distinguished by animals that have hair, mammary glands, and three middle ear bones

Have live births

Timeline of Evolution

550 million years ago: Agnatha

500 million years ago: Chondrichthyes

490 million years ago: Osteichthyes

360 million years ago: Amphibia

300 million years ago: Reptilia

200 million years ago: Mammalia

150 million years ago: Aves

Chordata

The three classes of the Chordata Phylum

Basics

Chordata phylum is based on the animal at some point in their lifetime having: Notochord which is a flexible skeletal support

rod embedded in the animal’s back Hollow nerve cord which runs along the

animal’s back Pharyngeal slits through the body wall in the

pharynx. Allows water to pass through slits without going through digestive system

Tail extends beyond anal opening

Vertebrates

Larger, active animals that have a well developed brain encased in a hard skull. Like a camel

Tunicates

Otherwise known as urochordates

Includes both sessile and free-swimming such as sea squirts

Lancelets

Otherwise known as the cephalochordates

Small eel-like animals that are commonly found in the shallow tropical oceans