Fish (Chapter 30.2 )

1. Fish (Chapter 30.2) Please set up your notebook for Cornell Notes

2. What is a fish? • Characteristics • Aquatic vertebrates, most have paired fins, scales and gills • Form and function • Feeding • Herbivores, carnivores, parasites, filter feeders and detritus feeders • Food enters mouth, passes through esophagus to stomach, goes through intestines and out anus

3. Respiration • Most fish use gills • Gills are made up of feathery structures called filaments • Water is pulled in through mouth and pumped over the gills for gas exchange • Excretion • Use gills and kidneys to excrete ammonia waste • Kidneys also help regulate amount of water in the body

4. Circulation • Closed, single loop • Heart – 4 parts (2 chambers) • Sinus venosus thin walled sac that collects blood before sending it to the atrium • Atrium  large, muscular chamber that holds blood before it enters the ventricle • Ventricle  a think walled chamber that does the pumping of the blood • Bulbous arteriosus large, muscular tube that connects to aorta, blood then goes to the body

5. Response • Well developed nervous system • Brain with specialized regions • Olfactory bulbs  sense of smell • Cerebrum  processes information from olfactory bulbs • Optic lobe  processes info from eyes • Cerebellum  coordinates body movement • Medulla oblongata  controls internal organs • Lateral line system  a system of receptors on the side of the body that can detect changes in current and vibrations in the water

6. Movement • Most move by alternating muscles in either side of the vertebral column • Use fins to propel forward and to steer • Fish are more dense that water, use swim bladder to adjust buoyancy • Reproduction • Fertilization occurs either internally or externally • After fertilization • Oviparous  salmon • Ovoviviparous  Guppies • Viviparous  some sharks

7. Classes of fish • Class Agnatha jawless fish • Subclass Cyclostomata hagfish and lampreys • Lampreys  filter feeders as larva and parasitic as adults • Have a circular sucking disk w/ a round mouth in center • Attach to fish, whales and dolphins, drill hole in side and suck up tissues and body fluids • Hagfish  feed on dead and dying fish • No eyes but light detecting sensors on body • Secrete slime, have six hearts, open circulatory system and tie themselves into knots

8. Class Chondrichthyes Cartilaginous fish • Cartilage  strong tissue that supports body but is softer and more flexible than bone • Subclass Elasmobranchii sharks, skates and rays • Sharks  torpedo shaped body, large curved tails and pointed snouts with mouth underneath • Rows of teeth that are constantly replaced • Some sharks are filter feeders • Skates and rays  diverse feeding habitats • Glide with flapping motion of large, wing-like pectoral fins • Subclass Holocephali chimaeras (ghost shark) • Elongated, soft bodies with a bulky head and single gill opening

9. Class Osteichthyes bony fish • Subclass Actinopterygii ray-finned fish • Have slender bones in fins • Make up 99% of all fish species • Freshwater and marine • Subclass Sarcopterygii lobe finned fish • Lung fish, coelacanth • Fleshy fins have stronger, jointed supporting bones