The Chordates Phylum Chordata The Chordates at some

The Chordates Phylum Chordata – The Chordates at some point in their life have a notochord, a nerve cord, and slits in their throat area.

The NOTOCHORD • Rod that supports the animal’s back – Some keep it all their lives, ex. lancelet – Others have a notochord as larva, but not as adults, ex. tunicate – Vertebrates have a notochord called a backbone

Other Characteristics of Chordates • Nerve chord (spinal cord) • Pharyngeal slits – these slits become part of the gills in fish, most other vertebrates lose these slits before birth

Vertebrate Characteristics • Most Chordates are vertebrates – Backbone is part of an endoskeleton • Protects the body, helps give it shape • Includes the vertebrae, skull, etc. – Backbone grows as the organism does – Supports the body against the downward pull of gravity

Separating Vertebrates • Ectotherm – body temperature changes as the environment changes – Ex. fish, reptiles, amphibians • Endotherm – animal that controls and regulates its body temperature by controlling the internal heat it produces. – Ex. mammals and birds • Require fur, feathers, or sweat glands

Vertebrates: A Review

Chordate Classes The Fish • Pgs. 374 -380

Fish Body Characteristics • Body Symmetry: Bilateral • Cell Organization: Cells to tissues to organ systems • Reproduction: Sexual • Body Development: – Internal Fertilization: eggs are fertilized inside the female’s body and when they are mature she gives birth to them. – External Fertilization: male releases sperm over the eggs the female releases. The eggs develop outside her body.

Classes of Fish – Jawless fish • Ex. Hagfish and lampreys – Cartilaginous fish • Sharks, rays, skates – Bony fish • Trout, tuna, goldfish, etc.

• Have no jaws and no scales Jawless • Cartilage skeleton • Have mouths containing structures for scraping, stabbing, and sucking their food • Hagfish and Lampreys are the only existing jawless fish today • Hagfish are scavengers and feed on the bodies of dead or dying fish • Lampreys are parasites and attach to fish and suck in tissue or blood Fish

Cartilaginous Fish • Have jaws, scales, and skeletons made of cartilage • Sharks rely on swimming to move water over their gills to get oxygen from the water. • Rays and skates take in water through holes behind their eyes while they are buried and release the water through their gills. • Carnivores

Bony Fish • Have jaws, scales, and gill pockets. • Skeletons are made of hard bone. • Bony fish have a swim bladder: internal gasfilled sac that helps the fish stay stable at different depths in the water. • Make up 95% of all fish species • Live in salt and fresh water

Chordate Classes The Reptiles • Pages 387 -394

Body Characteristics • Body symmetry: Bilateral • Cell organization: Cells to tissues to organ systems • Reproduction: Sexual • Body Development: Eggs with shells hold embryos that hatch into young which grow into adults

Orders of Reptiles • • • Lizards Snakes Turtles Alligators Crocodiles Dinosaurs (extinct)

Lizards and Snakes • Skin covered with overlapping scales that shed • Most lizards and ALL snakes are carnivores • Snake’s jaw can unhinge itself to eat its prey whole. • Some snakes have teeth with venom Snake eating a kangaroo

Alligators and Crocodiles • Carnivores that hunt at night • Alligators – broad snouts, few teeth visible • Crocodiles – pointed snouts, most of their teeth are visible • Only reptiles that care for their young

Turtles • Ribs and backbone attached to a protective shell (they can’t shed it). • No teeth; sharp beak • Carnivores or herbivores • Tortoises are land turtles