chap 28 and chordata

Echinoderms (a phylum)

includes sea stars and sea urchins

echino- spiny

derma-skin

nerve ring water vascular system

Chordates

Include the vertebrates but not alll are

Animals that at some stage have a notochord, gill slits, a dorsal nerve cord, and a post-anal tail.

Class Asteroidea e

includes sea stars and sea daisies

scavenger feeders

Class Ophiuroidea e

includes brittle stars

scavanger feeders

Class echinoidea e

includes sea urchins and sand dollars

no arms but 5 rows of tubefeet

spines are used for locomotion and protection

Class Crinoidea e

sea lillies

non moving

attach to coral reefs

Class Holothuroidea e

sea cucumbers

lack spines and have 5 rows of tube feet

What is a chordata

The 4 things to make one qualified

Dorsal hallow nerve cord

Notochord (protects nerve cord)

Post anal tail

Pharyngeal gill slits

Invertebrates Chordata

Cephalochordate (lancelets) potential ancestor for invertebrates 

Urochordata(tunicates)

they still have a notocord

lack boney structure

jawless vertebrates

Myxini(hagfishes)

Petromyzontidia (lampreys)

primitive

Cartilage based fish

Chondrichthyes (sharks rays and chimaeras)

bony fish

Actinopterygii (ray finned fishes)

Lobed: Actinistia (coleacanths)

lobed: dipnoi (lungfishes

tetrapods (four legs)

amphibia (frogs and salamander)

Reptilia (turtles snakes crocolidles birds)

Mammalia (mammals)

Vertabrates (gnathostomes) or (jaw)

Chordates are considered vertebrates only when their notochord is replaced by a backbone made of bone or cartilage

Chondrichthyes, Actinopterygii, Actinistia, Dipnoi, Amphibia, Reptilia, Mamillia  

chordates vs vertebrates 

Chordates are considered vertebrates only when their notochord is replaced by bone or cartilage.

So chordates with no bones would be invertebrates because bones are the defining structure that differentiates the invertebrates from vertebrates. 

Vertabrata (craniata)

needs an enclosing spinal cord (doesnt need to be bone)

notochord needs to wrap the nerve cord 

in elaborate skull

fins rays