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 300 million years ago: Reptilia 150 million years ago: Aves 490 million years ago: Osteichthyes 500 million years ago: Chondrichthyes 360 million years ago: Amphibia 200 million years ago: Mammalia

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