Phylum Chordata

Section 30-1

Nonvertebratechordates

FishesAmphibians

ReptilesBirds

Mammals

Invertebrate ancestor

Chordate Cladogram

Chordate Characteristics

All chordates at some point in their life cycle have:

-dorsal hollow nerve cord (brain/spinal cord)

-notochord (vertebral column)

-pharyngeal pouches (pharynx)

-tail extending beyond the anus

Subphylum: VERTEBRATAAbout 96% of chordates are vertebratesApprox. what % of all animals are vertebrates?Internal framework called an endoskeleton

made of cartilage or boneHave a skull that protects the brainVertebral column or backbone that protects the

spinal cord Rib cage to protect internal organsMost have two pairs of limbsMost taxonomists divide vertebrates into seven

classes.

7 Classes of Vertebrates:1. Class Agnatha – jawless fish ex: lamprey, hagfish *minimal

skeleton, no true teeth2. Class Chondrichthyes – cartilage fish ex: shark, skates &

rays*entire skeleton is cartilage3. Class Osteichthyes – bony fish *most fish belong to this group

and their skeleton is made largely of bone ex: perch, carp, seahorse.

4. Class Amphibia – amphibians ex: frogs, toad, salemander *most have an aquatic larval stage (breath through skin/gills) and adults have lungs

5. Class Reptilia – reptiles ex: snakes, lizards, crocs *lay eggs on land

6. Class Aves – birds *have feathers, most fly, beaks/bills ex: hawk, heron, crow, emu

7. Class Mammalia – mammals *hair or fur and develop internally and nurse off milk after birth, 4 chambered heart ex: shrews, whales, bats, horses, tigers, elephants, rabbits, humans

Fish Agnatha: jawless fish

Chondrichthyes: cartilage fish

Osteichthyes: Bony fish

AmphibiansFrogsToads

Salamanders

ReptilesSnakes

Lizards

Crocodilians

Turtles

Aves:The Birds

Mammalia: the mammals

Nonvertebrate Chordates

-These animals have no backbone, but do have a notochord.

-Also have a dorsal hollow nerve cord, pharyngeal pouches and a tail.

-Two sub-phyla: Urochordata and Cephalochordata

-Although very different from vertebrates, they are distant relatives

Urochordata: The Tunicates -Filter-feeders

-Name comes from the tough covering called a tunic

-Called sea squirts

-Larvae have all four chordate characteristics

-Adult tunicates have no notochord or tail

Tunicate Larva

-Notochord

-Hollow dorsal nerve cord

-Pharyngeal pouches

-Tail

Cephalochordata: Lancelets

- Small fish-like animals that live in the sandy bottom.

-Have a head region with a mouth.-Lancelets take water into their pharynx and pick out food.

-Pharynx has up to 100 pairs of gill slits

-Have a circulatory system but no heart. Blood is moved by the vessels.