PHYLUM CHORDATA

Includes all vertebrates and two groups of invertebrates

Have four characteristics during some stage of their life; Notochord Dorsal nerve chord Pharyngeal pouches/gill slits Postanal tail

NOTOCHORD

Is a stiff flexible rod of cells that runs dorsally the length of the body

provides a strong surface for muscles to attach

usually present in the embryo of vertebrates but becomes reduced when the backbone develops

DORSAL NERVE CHORD

is a hollow tube where the anterior end enlarges to form the brain and the posterior end forms the spinal cord

PHARYNGEAL POUCHES

out pockets in the pharynx develping into gills for aquatic organisms and jaws, inner ear, tonsils for terrestrial organisms

POSTANAL TAIL

Aquatic chordates possess this characteristic as an adult acts as a form of propulsion in the water

PHYLUM CHORDATA

Deuterostomes Coelomates Divided into three subphyla:

Vertebrata (95% of all chordate species) Cephalochordata Urochordata

SUBPHYLUM CEPHALOCHORDATA

Includes lancelets Keep notochord, dorsal nerve chord,

pharyngeal pouches, and postanal tail They live in warm, shallow waters where

they wiggle backwards into the sand. Cilia pull water into their pharynx where

food is trapped in the slits entering the intestines to be digested.

SUBPHYLUM UROCHORDATA Includes sea squirts (tunicates) Bodies are covered with a thick tough

covering called tunic. Sessile barrel-shaped animals that live on the

bottom of the sea. Larval forms possess all four chordate

characteristics but loose them during metamorphosis.

As adults they have a pouch-like pharynx with slits, are filter-feeders and hermaphrodites.

SUBPHYLUM VERTEBRATA

at some stage they have a notochord, dorsal nerve chord, pharyngeal pouches, and a postanal tail

distinguished from other subphyla by three characterisitics; Vertebrae Cranium endoskeleton of bone or cartilage

THE MAJOR GROUPS OF VERTEBRATES

Class Agnatha (lampreys and hagfish), elongated eel-like bodies, lack jaws, paired fins,

and bone Class Chondricthyes (sharks, rays, and skates)

predatory fish have jaws and paired fins, their skeleton is made of cartilage, skin is covered in a unique scale

Class Osteichthyes (bony fish) they have jaws, boney skeleton

Class Amphibia (Amphibians) skin is thin, lay eggs in water and have an aquatic

larval stage

THE MAJOR GROUPS OF VERTEBRATES

Class Reptilia (Reptiles) skin is dry and scaly, eggs are laid on land

and protect the embryo from drying out Class Aves (Birds)

they have adapted for flight through wings, hollow bones, unique respiratory system

Class Mammalia (Mammals), they grow hair and nurse their young