Subphylum Vertebrata Kingdom Animalia Phylum Chordata Subphylum Vertebrata Have Backbone = vertebrae (plural) vertebra (singular) Dorsal row of hollow skeletal elements which enclose and protect the nerve cord. Spinal cord ends in a brain attached to spine Fish Amphibians Reptiles Birds Mammals
Fish 24,000-30,000 species, ~15,000 are marine Most abundant vertebrates Eukaryotic, multicellular Organ level of organization Bilateral symmetry Endoskeleton, made of bone or cartilage
General Fish Characteristics Gills Backbone (vertebrae) Paired Fins Single Loop Circulation Two chambered heart
Fish have a two chambered heart and single loop circulation: blood is passed over the gills where it picks up oxygen, goes to the body and returns to the heart
Fish Respiration Water flows over gills as fish opens mouth and swims. Water flows opposite direction of blood flow.
Fish Respiration O 2 diffuses from the water into the blood. Gills are made of thousands of gill filaments. Gills are covered by the 0perculum.
FISH 3 classes Agnatha Jawless fish Chondrichthyes Cartilaginous fishes Osteichthyes Bony fishes
The jawless fishes: Agnatha Most primitive Lack jaws and paired fins Feed by suction: teeth and muscular mouths Elongated cylindrical body Cartilaginous skeletons
Hagfish “Slime eels” Secrete large amounts of mucus from skin when agitated Feed on dead or decaying fishes Bore into prey, eat them from inside out. Knot and slide technique Hagfish Slime and sharks Hagfish Info
Lamprey fresh and salt water Breed and hatch in freshwater rivers and lakes Live/feed at sea as adults Parasitic, suck blood from other fish Predators of bottom invertebrates
Chondrichthyes Include: Sharks Rays Skates Ratfish Paired fins (often stiff) Skeleton made of cartilage Lighter, more flexible than bone RAY RATFISH SHARK SKATE
Chondrichthyes Moveable jaws with well developed teeth “Conveyor belt” teeth replacement Placoid scales- rough, sandpaper skin Teeth and skin composed of same material.
Spiracles: 1 st pair of gill slits modified, used to take in water even when ventrally located mouth in sediment Heterocercal caudal fin: upper lobe extends further than lower lobe
Sharks Paired pectoral fins Great predators (teeth and speed) great whitesgreat whites 5 to 7 gill slits Two dorsal fins Nictitating membrane = extra eye lid, protects eye during feeding Nares for smell Great whites can detect one drop of blood per every 1 million drop of water from 2 miles away!
Ampullae of Lorenzini Lateral line Gel-filled sensory pores Detect weak electrical fields Such as: muscular contractions, heart beats, nerve impulses Sense irregular swimmers Pores along body that detect water vibrations and pressure Allows to avoid obstacles, orient to currents, detect prey Special senses
Hammerhead Flattened head Eyes and nares separated for improved sensory intake Thresher Very long upper lobe of caudal fin Herd and stun fish
Diversity: filter feeders Whale Shark: largest fish Eat plankton! Basking Shark-2 nd largest
Angel Sharks Saw shark Flattened body Bury in sediment Diversity: Body shape video video Alternating tooth size Blade like snout
Rays and Skates Examples Sting rays, electric rays, guitarfish, sawfish, skates, manta rays Often flattened Mostly live on bottom = demersal Pectoral fins are flat, expanded, fused with head Eyes on top of body typically.
Skates and Rays Feeding Feeding Teeth modified into grinding plates Eat clams, crabs, anything in sediment Uncover prey by sifting sediment with pectoral fins
Ray gills 5 gill slits always on the underside of body Spiracles on top to pump water over gills when lying on sediment
Rays Skates Whip like tail, often containing poison Stinging spines Give birth to live young Lack whip like tail and poison Lay egg cases Rays vs. Skates
Ratfish-chimieras Mostly deep water One pair of gill slits Cartilaginous Bottom dwellers often Feed on bottom dwellers Sometimes, a snout-like nose
Videos Chondrichthyes diversity Which way to angel shark teeth curve? How do wobbegong sharks attract fish? What are the sensory organs used for on saw sharks?
Rays Diversity How many species of rays are there? How do rays differ from sharks?
Reproduction Most fish lay eggs that are fertilized externally - called spawning Some fish bear live young
Fish Adaptations Lateral Line System- used to detect vibrations, orient the fish in water, it is a line of cells running down the side of the fish. Operculum- gill cover, movement of operculum allows more water to be drawn in. Swim Bladder- a gas filled sac that helps the fish maintain buoyancy. Sharks don’t have a swim bladder Fins- Dorsal, Caudal, Pectoral, Pelvic, Anal.