Introduction to Fish

Animal characteristics Heterotrophic Eukaryotic and lack cell walls Exhibit embryonic development Actively move Invertebrates vs. vertebrates

Kingdom Animalia: Phylum Chordata At some time during development, all animals have had Notochord – long flexible rod – replaced by vertebrae Tail posterior to anus Pharyngeal gill slits – become jaw structure Dorsal Hollow nerve cord that develops into central nervous system( brain and spinal cord)

Jawless fishes - Class Agnatha Lack Jaws Lack paired appendages Cartilaginous skeleton No scales hagfish Benthic Hide is used for leather products Feed using two dental plates and tear out pieces of pre Lamprey Fresh and marine Feed using oral dish with rasper tongue

Cartilaginous fish – sharks skates and rays Holocephalans Chimaeras or ratfish elasmobranchs Two body types Elongated (sharks) Flattened (rays) Class Chondrichthyes Cartilaginous skeleton Have jaws and paired fins Covered with Placoid scalesPlacoid scales

Bony fish – Class Osteichthyes (95% of all fish are members of this class) Swim bladder Bony skeleton Bony scales Fins Lobe finned fish Coelacanths, lungfish Coelacanths Have lobed fins that look like appendages Ray finned fish Perch, marlin, tuna Two major groups Shark/ Fish video

Fish identification Shape behavior Habitat Patterns color size Color and size not very reliable Differences in perception Water magnifies size about 30%

Other field marks to look for: Patterns – bars, stripes, bands, spot Eye placement and size – tells where fish is looking for food and whether diurnal or nocturnal Fin shape Lateral line - a series of small canals containing pressure sensitive receptors, helps the fish to navigate even when vision is greatly impaired

Lateral Line Operculum Fish Video