Fish Gill breathing, ectothermic, aquatic vertebrate that has fins, skin covered in scales.

Classes of fish Myxini – Hagfishes Cephalaspidomorphi- Lampreys Chondrichthyes- Cartilaginous fish (sharks-rays)

2 classes of bony fish Actinopterygii – ray finned fishes – 23,000 species Sarcopterygii – lobe finned fishes(fleshy) – 8 species (coelacanth)

Modes or reproduction Oviparous – egg layed Ovoviviparous-Developing young stay in oviduct and are nourished by yolk sac Viviparous- true live bearing – nourished by placenta

Myxini Hagfish Scavengers 43 species Almost blind Keen sense of smell Hooks onto prey two toothed plates

Myxini Eel like body Slime glands(milky white) No fins Caudal fin along dorsal surface Cartilaginous Smooth skin(naked) No stomach No cerebellum Fluids same as seawater No larval stage Possess both sex organs only one functional

Cephalaspidomorphi Lamprey mouth Holds rocks to anchor Parasitic and predaceous

Cephalaspidomorphi Sexes separate Single gonad Sucker mouth Well developed teeth 17 species found in North America Also found Eurasia Breed in freshwater Anadromos – swim up river

Cephalaspidomorphi Lampreys attached Eel like Naked skin Regulated body fluids No stomach Well developed eyes

Chondrichthyes Sharks Rays Skates 850 living species

Chondrichthyes Rays Specialized for life on the sea floor Skates Electric rays Sting rays Bat rays

Chondrichthyes Rays Gill openings on underside of head Spiracles on top Water taken in through the spiracles

Chondrichthyes Many sharks don’t survive in captivity or they act very different in aquariums So many species of sharks are still not well researched

Chondrichthyes Pelvic fins in male modified to form claspers Fusiform body(spindle) Two olfactory sacs Endoskeleton entirely made up of cartilage Five to seven sets of gills No swim bladder or lung Keen sense of smell Lateral line Electroreception Moderate vision

Chondrichthyes Separate sexes Internal fertilization Oviparous Ovoviviparous viviparous 25 freshwater 2nd largest vertebrates Heterocercal tail-turns up

Sarcopterygii- fleshy finned

Actinopterygii Bony fish

rockfish

Osteichthyes - Actinopterygii Perch

Osteichthyes- Actinopterygii Clownfish

Osteichthyes Seahorse

Osteichthyes Seahorse

Osteichthyes Piranha

Osteichthyes

Osteichthyes 410 million yrs ago Most numerous and diverse group of vertebrates Diverse body form Specialized jaws Capable of osmotic regulation Separate sexes External fertilization

Respiratory Functions (Exchange of Gases) Mouth-Take in oxygen(water) and food Operculum-(Protects gills)-Opens and closes to help oxygen move over the gills-increases efficiency

Water enters mouth travels to pharynx(throat)and passes over gills The outward motion of the Operculum creates a negative pressure increasing volume of water over gills

Early fish The first fishes had a lack of paired fins and no jaws Decreased mobility and sources of food Development of jaws expanded food sources available Carnivores /herbivores etc.

Locomotion Functions (Movement to Keep Upright) Pectoral Fins and Pelvic Fins-Used for steering, slow swimming and to keep the fish upright Dorsal and Anal Fin-Used for stability Caudal Fin-Used for movement and fast swimming

Pectoral fin – front legs Pelvic fin – hind legs

Protective Functions Skin Pigment-Provides camouflage Scales-Protects the skin, parasites, easier swimming

Sensory Functions (Transfer Stimuli to Nerve Impulses) Nostrils-Lets chemicals into the nostril cavity (smell, olfactory bulbs) Eyes-Large pupils let more light in to help seeing Lateral Line-Connection of nerve endings that carry low frequency vibrations and depth pressure. Depth and solid objects. Tongue-touch, oxygen movement, food movement

Anadromous- lives at sea return to fresh to spawn - salmon Catadromous- lives in fresh water return to sea to spawn- eels Homing instinct regulated by smell of parent stream Position of sun gets them to the river mouth From ocean

Internal Anatomy Respiratory-gases between blood and oxygen Gill-Oxygen passes over the gills, O2 is absorbed through the membranes of the Filaments by diffusion.

Countercurrent blood flow Blood circulation is opposite water flow Allows for maximum efficiency of oxygen absorption 85% Some fish need to keep moving

Circulatory Functions-O2, Nutrients, Remove wastes Heart-2 chambered-Pumps only deoxygenated blood Spleen-Removes old blood cells

Deoxygenated blood goes through heart to gills then to body of fish to deliver oxygen

Closed system – separate oxygenated and deoxygenated blood Single pump/single loop

Locomotion Air/Swim Bladder-Adjusts float level by changing density of gases Ears-helps to maintain balance and equilibrium

Weberian ossicles are small bones that transmit sound vibrations from swim bladder to the inner ear. Hearing of faint sounds improved catfish

Digestive Functions-Absorption of Food into the Blood Teeth-used to bite and hold food Esophagus-used to carry food to the stomach Intestine-digestion of food and absorption of the food Stomach-digestion and storing of food Pyloric Caeca-secretes digestive enzymes Liver-makes bile to aid in digestion Gall Bladder-digests fats

Excretory Functions-Removal of Metabolic wastes from body Kidney and gills-removes nitrogen from blood

Solid wastes removed through anus