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Diversity of fishes

The document summarizes the diversity of fishes, including their defining characteristics and classification. It describes the three main classes of fishes: jawless Agnatha such as hagfish and lampreys, cartilaginous Chondrichthyes including sharks and rays, and bony Osteichthyes such as ray-finned fish. Key traits discussed include types of skeleton, presence of jaws, fins, and scales. Examples are provided of distinguishing features for different groups like sharks, rays, and bony fish.

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4. Diversity of Fishes Kingdom - Animalia Phylum - Chordata 3 Classes: Agnatha, Chondrichthyes, Osteichthyes
Vertebrates: Ex: fish, amphibians, reptiles, birds, & mammals Have a notochord (slim, flexible rod) present in early stages - may be replaced by backbone in adults Have a spinal cord Respire through pharyngeal or gill pouches during early development Have post-anal tail in early stages Endoskeleton made of bone &/or cartilage Anterior head with well developed brain & sensory organs (Cephalization) Closed circulatory system
Taxonomy: 1. Class Agnatha: hagfish & lamprey-long, eel-like bodies without jaws or paired fins & cartilage skeletons
Agnatha (Jawless Fish): Hagfish& lampreys Circular mouths that can’t close Sharp teeth & strong, raspy tongue-tears hole in prey & sucks out blood & body fluids Eel-shaped body Skeleton made of cartilage No paired fins Gills – no operculum Hagfish: burrow in mud; scavenge on dead & dying fish; have tentacles around their mouth Lampreys: usually parasitic; great sense of smell to find prey; covered with a poisonous slime
Lamprey with Prey
2. Class Chondrichthyes include sharks, rays, & skates also with cartilage skeletons , paired fins, & jaws
Characteristics of  the more advanced fishes:   Streamlined body & muscular tail for swimming (know the differences between tail shapes!) Most - paired fins for maneuvering Body covered with protective scales & mucus layer to reduce friction when swimming Respire through gills Most - lateral line system-sensory structures running down each side of the organism to detect changes in water temperature, pressure, current, etc.
Most w/ well-developed sense of sight & smell Most can detect electrical currents Ectotherms (body temperature close to outside temp.) Two chambered heart (1 atrium/1ventrical)
Class Chondrichthyes Includes sharks, rays, & skates Endoskeleton of cartilage Hinged jaws & paired fins Placoid scales & tooth-like dermal spines on scales Most Marine Most Carnivorous
Sharks vs. Rays Sharks are torpedo shaped=“fusiform” Rays & skates have broad, flat bodies with wing-like fins and a tail
Shark Characteristics: Large, oily liver helps w/ buoyancy Have countershading: protective coloration (darker top & lighter bottom) Ventral mouth with 6-20 rows of sharp, replaceable teeth Short, straight intestine with spiral valve to slow food movement 5-7 pairs of gills for gas exchange Kidneys remove wastes & maintain water balance Electroreceptors on head help find prey & navigate Lateral line Separate sexes - external fertilization
Ray & Skate Characteristics: Usually harmless to humans Broad, wing-like pectoral fins used to glide through water Flattened bodies with ventral mouth Both eyes on top of head Have countershading Feed on fish & invertebrates Stingray with poison spine by tip of tail Electric ray gives off strong, electric shock Manta ray is largest
Traits of Bony Fish (Class Osteichthyes) Skeleton made of bone Hinged jaws Paired fins Gills for gas exchange Lateral line Body covered with scales & mucus coating Includes lobe-finned, ray-finned, and lung fish
Ray-finned Fish: Fan-like fins supported by rays Includes salmon, perch, catfish, tuna, etc. Have movable fins Dorsal fin (s) located on top-keep fish upright & used for defense Caudal fin (tail) moves side to side to help steer Pectoral fins (paired) on each side behind the operculum Pelvic fins (paired) on ventral surface near the head Anal fin (single) behind anus
Ray-finned Fish (cont.): Swim bladder thin-walled sac in abdomen that creates buoyancy from diffusion of dissolved gas from blood Kidneys filter blood & help maintain water balance Ectothermic - body temperature regulated by envt. Keen sense of smell (nostrils) & have chemical receptors over the body Can detect the earth's magnetic field as a guide to navigate oceans Have separate sexes & external fertilization Eggs hatch into fry
Body covered with round, overlapping cycloid or ctenoid scales & mucus Four sets of gills covered by bony operculum
External Anatomy of a Bony Fish
 
Guess What These Are:
Sites for Help on Vertebrates & Fish in Particular http://www.infovisual.info/02/033_en.html http://kentsimmons.uwinnipeg.ca/16cm05/1116/chordate.htm http://www.fishbase.org/home.htm