Phylum Chordata Characteristics of Chordates Notochord Dorsal nerve

Phylum Chordata

Characteristics of Chordates ► Notochord ► Dorsal nerve cord ► Pharyngeal pouches or gill slits ► Postanal tail

► Subphylum Cephalocharodata. This subphylum is composed of about 2 dozen blade-shaped animals known as lancelets. They retain all characteristic throughout life. ► Subphylum Urochordata- This subphylum is commonly known as tunicates ( sea squirts). Larva posses all chordate characteristics while adults exhibit only Pharyngeal pouches.

Subphylum Vertebrata ► All characteristics of chordates ► Distinguishing characteristics § Vertebral column or spine § Cranium or skull that protects the brain § Endoskeleton composed of bone or cartilage

Major groups of Vertebrates

Lampreys and Hagfishes ► Long, eel-like bodies ► Lack jaws ► Paired fins ► bones

Sharks, Skates and Rays ►Class Chondrichthyes § Jaws § Paired fins § Skeleton of cartilage

Boney Fishes ► Class Osteichthyes § Jaws § Most have a skeleton composed of bone

Amphibians ► Class Amphibia § Included frogs, toads and salamanders § Skin is moist and permeable to gases and water § Most lay eggs in water § Most have an aquatic larval stage

Reptiles ► Class Reptilia § Turtles, crocodiles, alligators, lizards and snakes § Skin is dry and scaly § Eggs that can be laid on land

Birds ►Class Aves § Adapted for flight ►Feathers ►Hollow bones ►Unique respiratory system

Mammals ► Characteristics § Endothermy § Hair § Completely divided four chamber heart § Milk produced from mammary gland § Single jawbone § Specialized teeth

Order Monotremata ► Egg-laying mammals ► Most primitive of mammals ► Only three species § Two anteaters and one platypus

Order Marsupialia ► 250 species ► The U. S. has only one species – the Virginia opossum ► Young develop in a pouch

Placental Mammals ► Diverse group composed of at least 18 orders ► 95% of mammals are placental ► They live on land, in water and the air