Fish UnitFish Unit

Fish Facts:Fish Facts:

More that 24,000 species Found in a wide range of habitats Specialized for their environment Fresh & saltwater environments have different

effects on fish Freshwater fish continually urinate (hypotonic) Saltwater fish continually drink water

(hypertonic)

More that 24,000 species Found in a wide range of habitats Specialized for their environment Fresh & saltwater environments have different

effects on fish Freshwater fish continually urinate (hypotonic) Saltwater fish continually drink water

(hypertonic)

SpecializationsSpecializations

Gills: Fins: Scales: Slime coat: Lateral line: Color patterns:

Gills: Fins: Scales: Slime coat: Lateral line: Color patterns:

Fish ClassesFish Classes

Class Agnatha: Jawless fishes No scales

Hagfishes Bottom dwellers in cold marine waters Often burrow into bodies of dead fish Can tie their bodies in knots to evade capture

Lampreys Many are parasitic Some live in freshwater, some saltwater, etc All reproduce in freshwater

Class Agnatha: Jawless fishes No scales

Hagfishes Bottom dwellers in cold marine waters Often burrow into bodies of dead fish Can tie their bodies in knots to evade capture

Lampreys Many are parasitic Some live in freshwater, some saltwater, etc All reproduce in freshwater

Class ChondrichthyesClass Chondrichthyes

Skeletons made of cartilage Advantage: lightweight, flexible, strong All species are carnivores, some scavengers Feed off a variety of foods Skin covered with placoid scales Includes sharks, skates, rays, sturgeon Internal fertilization rather than external

Skeletons made of cartilage Advantage: lightweight, flexible, strong All species are carnivores, some scavengers Feed off a variety of foods Skin covered with placoid scales Includes sharks, skates, rays, sturgeon Internal fertilization rather than external

Class OsteichthyesClass Osteichthyes

Bony fish Have lungs (early bony fishes) or swim bladder Swim bladder helps to control buoyancy Have scales Divided into lobe-finned fishes and ray-finned

fishes

Bony fish Have lungs (early bony fishes) or swim bladder Swim bladder helps to control buoyancy Have scales Divided into lobe-finned fishes and ray-finned

fishes

External AnatomyExternal Anatomy

Operculum - bony gill cover Fins - supported by bony rays or spines Rays give the fin strength Skin covered with scales Scales used mainly for protection

Operculum - bony gill cover Fins - supported by bony rays or spines Rays give the fin strength Skin covered with scales Scales used mainly for protection

Digestive SystemDigestive System

Esophagus = throat Stomach - secretes acids, digestive enzymes Intestine - nutrients absorbed here Liver - secretes bile, which helps break down

fats Gallbladder - stores bile Pancreas - releases digestive enzymes into

intestine Undigested material eliminated through anus

Esophagus = throat Stomach - secretes acids, digestive enzymes Intestine - nutrients absorbed here Liver - secretes bile, which helps break down

fats Gallbladder - stores bile Pancreas - releases digestive enzymes into

intestine Undigested material eliminated through anus

Circulatory SystemCirculatory System

Arteries - move blood away from the heart Veins - move blood to the heart Capillaries are smallest blood vessels (gas

exchange) Heart anatomy: Blood collects in sinus venosus Moves to atrium Moves to ventricle Moves to conus arteriosus Then moves to body….

Arteries - move blood away from the heart Veins - move blood to the heart Capillaries are smallest blood vessels (gas

exchange) Heart anatomy: Blood collects in sinus venosus Moves to atrium Moves to ventricle Moves to conus arteriosus Then moves to body….

Respiratory SystemRespiratory System

Fish breathe by using “countercurrent flow” Water flows away from head, blood flows

towards head Very efficient gas exchange in capillaries

Fish breathe by using “countercurrent flow” Water flows away from head, blood flows

towards head Very efficient gas exchange in capillaries

Nervous SystemNervous System

Brain has cerebrum (central processor) Cerebellum coordinates motor output Medulla oblongata - acts as a relay station for

stimuli & sensory receptors Basically, the m.o. sends sensory signals

where they need to go Lateral line system used to detect vibrations &

pressure changes

Brain has cerebrum (central processor) Cerebellum coordinates motor output Medulla oblongata - acts as a relay station for

stimuli & sensory receptors Basically, the m.o. sends sensory signals

where they need to go Lateral line system used to detect vibrations &

pressure changes

Pacific SalmonPacific Salmon

Five species: Chinook (King) Coho (Silver) ….best fighting salmon Chum (Dog) Sockeye (Red) Pink (Humpback) Spend several years (up to 5-6) in saltwater then return

to freshwater to spawn (anadromous) Smell their way back to their spawning grounds Die after they spawn Young have “parr marks” for camouflage

Five species: Chinook (King) Coho (Silver) ….best fighting salmon Chum (Dog) Sockeye (Red) Pink (Humpback) Spend several years (up to 5-6) in saltwater then return

to freshwater to spawn (anadromous) Smell their way back to their spawning grounds Die after they spawn Young have “parr marks” for camouflage