THE VERTEBRATE ANIMALS All Vertebrates are Chordates Phylum

THE VERTEBRATE ANIMALS

All Vertebrates are Chordates Phylum chordata! � Chordates ALL have 4 characteristics sometime during their lives � a notochord – flexible support rob in the back � Hollow nerve cord- forms from a section of the ectoderm � Pharyngeal (gill) slits- slits through the body wall where water can enter and not pass through the digestive tract. � a Tail –extending beyond the anal opening

99% of chordates are vertebrates Characteristics of Vertebrates � Bilateral Symmetry (can be equally divided along one plane) with 2 pairs of appendages � Cephalization (sense organs concentrated in a head region) � True body cavity � Closed circulatory system. � Endoskeleton including a braincase and a vertebral column � Well developed body systems.

Vertebrates Animals with backbones can be divided into five more groups: Mammals Birds Amphibians Reptiles Fish

Fish Are cold-blooded. 2 chambered hearts Lay eggs without shells Some give live birth Have lateral line system that is sensitive to small changes in water movement � Have a moist skin covered in scales. � Swimming motion is side to side � Breathe through gills (large sheets of thin frilly tissue filled with capillaries that take in oxygen from water. ) � � �

Amphibians � � � Tetrapods (four limbs) Are cold-blooded (ectothermic) Lay eggs. Have a smooth, moist skin. Are able to live on land as well as in the water.

Jawless Fish (Phylum Agnatha) � Primitive, no paired fins � no bone, all cartilage � Filter feeders and some feed on other organisms (sucking their blood) � Sexual reproduction � Live in the ocean Examples; Lamprey – a parasite and Hagfish – scavenger, also called slime eel.

Jawless Fish

Cartilage Fish (Phylum Chondrichthyes) � Have skeleton made of cartilage � 750 species � Live in the ocean � Reproduction- sexual with many species giving live birth � Feeding- carnivores and some filter feeders � Groups Holocephali- chimeras or ratfish Elasmobranchs- sharks, rays and skates

Cartilage Fish

Bony Fish � 20 -30, 000 species � Appeared 400 million years ago � Skeleton made of bone � Cold blooded, flat scales, swim bladder (which helps a fish float higher or lower in water, used for buoyancy) � Have a protective plate over their gills called the operculum � Most lay eggs � Eyes usually on the side of the head � Groups- Lobe-fins, Coelacanths and Lungfish

Bony Fish

Amphibians � 2000 species, appeared 350 million years ago. � Cold-blooded, claws, 4 legs � Lay moist skin, lungs, no jellylike eggs � Life cycle includes a larval stage. Meaning tadpoles metamorphic into terrestrial adults � 90% are frogs and toads � Live on both land water