Fish. Vertebrates (Subphylum Vertebrata) –Backbone enclosing a nerve cord, or spinal cord Phylum Chordata –Notochord –Pharyngeal pouches –Postanal tail.

Fish

• Vertebrates (Subphylum Vertebrata)– Backbone enclosing a nerve cord, or spinal cord

• Phylum Chordata – Notochord– Pharyngeal pouches– Postanal tail– Dorsal Nerve Chord

• Phylum Chordata– Subphylum Vertebrata– Class Agnatha, Jawless fishes, (Hagfishes and Lampreys)

– Class Chondrichthyes, Cartilaginous fishes, (Sharks, Sharks and Rays, Ratfishes)

– Class Osteichthyes, Bony fishes

Fig. 8.1

Tab. 8.1

Class Agnatha: Jawless Fishes

• Hagfishes and lampreys

• lack jaws, most primitive of living fishes

• Feed by suction

• Lack paired fins and scales

•Hagfish (slime eels)

•Lampreys, freshwater

Class Chondrichthyes: Cartilaginous Fishes

•Sharks, rays, skates, and ratfishes

•Endoskeleton of cartilage

•Paired fins, movable jaws, gill slits

•Rough sandpaper – like skin

• placoid scales

• pointed tip that is directed backward

• same composition as teeth

Fig. 8.3

Class Osteichthyes: Bony Fish

• Largest group of living vertebrates

• Gills covered by operculum

• Usually swim bladder

• Highly maneuverable fins

• Cycloid scales

Biology of Fishes

•Body ShapeDirectly related to its lifestylePredator or preyStreamlined, flattened, elongated, etcUsed for camouflage

Fig. 8.4

Biology of Fishes

• Coloration

– Chromatophores

• Locomotion– Swim using a sideways movement of the body and tail– Pectoral fins and tail

• Aid sharks with buoyancy

• Aid bony fish maneuver/swim

• Feeding– Carnivorous, herbivorous, filter feeders

Fig. 8.11

Fig. 8.10

Fig. 8.12

• Digestion– Same set up as all vertebrates

• Respiratory System– Obtain oxygen filtered from the water– Cartilaginous Fish

• First pair of gill slits modified into spiracles (pull water in)

– Gill filaments, fleshy projections• Lamellae, increase surface area

– Diffusion, countercurrent system of flow

Fig. 8.6

Counter – current flow

• Regulation of Internal Environment

– Marine fishes keep a constant internal environment

• Kidneys, gills, “drinking” water, rectal gland

• Cartilaginous fishes increase their solute concentration in their

blood

– Urea

– Created by breaking down proteins.

• Single – loop Blood Circulation– Simple chamber – pump heart

• Blood collects in atrium and leaves through ventricle

• In from body out to the gills

• Nervous System and Sensory Organs– Central Nervous System– Olfactory sacs, sense of smell, opens to nares– Taste buds– Barbels– Nictitating membrane– Lateral line, detect vibrations in the water (neuromasts)

Biology of Fishes

• Behavior

– Territoriality

– Schooling

– Migration

• Anadromous, fishes spend most of their lives in the sea but

migrate to fresh water to breed

• Catadromous, fishes spend most of their lives in fresh water but

migrate to salt water to breed

• Reproduction and Life History– Urogenital Opening

• sperm or eggs

– Hermaphrodites– Courtship– Internal fertilization

• Copulation

• Males cartiliginous fishes have claspers

– External fertilization

Biology of Fishes

• Oviparous– Spawn eggs

• Ovoviviparous– Eggs are retained in reproductive tract

• Viviparous– Live – bearers, nutrition comes from reproductive tract

• Parthenogenesis– Development of an egg without fertilization

Fig. 8.30

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