Chordates, at some stage in their lives, have a: Dorsal (hollow nerve cord), Notochord (supports nerve cord during embryonic phase), Pharyngeal pouches (paired slits in throat region – can become gills) Tail that extends beyond anus

Most Chordates are Vertebrate, meaning they have a back bone Fish, Amphibians, Reptiles, Birds and Mammals 2 exceptions TunicatesLancelets

Aquatic vertebrates; most have paired fins, scales, and gills

Environment  Salt and Fresh water  Most fish cannot live in both types of water because their kidneys cannot maintain homeostasis Food Source  Herbivores, carnivores, parasites, filter feeders, and detritus feeds (a single fish may exhibit several modes of feeding, depending on what type of food is available)

Maintaining Homeostasis - Internal (Circulation, Respiration, Excretion)  Have gills  Closed circulatory system with a heart that pumps blood around the body in a single loop from heart to gills then gills to rest of body  Rid their body of nitrogenous waste through ammonia through the gills or kidney Maintaining Homeostasis - External (Response)  Well developed nervous system with a brain, cerebrum, cerebellum, and a medulla oblongata.  Lateral line system- senses other fish or prey near by

Movement  They alternate contracting paired sets of muscles on either side of the backbone, creating a S-shaped curve down their bodies Reproduction  External or Internal fertilization  In many fish the female lays the eggs and the embryos develop and hatch outside of her body. Evolutionary Milestone  Vertebrate - notochord

 Picture on page 771 Figure 30-6  Vocabulary: cartilage(773), swim bladder(777)