Phylum Chordata Chapter The Fishes

Vertebrata– The Backboned Animals Characteristics Characteristics Most numerous & complex of Chordates Most numerous & complex of Chordates NTK 7 Classes NTK 7 Classes Agnatha, Chondrichthyes, Osteichthyes, Agnatha, Chondrichthyes, Osteichthyes, Amphibia, Reptilia, Aves, Mammalia Amphibia, Reptilia, Aves, Mammalia Spinal column replaces notochord Spinal column replaces notochord Anterior end of nerve cord modified into brain Anterior end of nerve cord modified into brain Body usually divided into head, neck & trunk Body usually divided into head, neck & trunk Two pair of appendages (arms & legs) Two pair of appendages (arms & legs) Heart w/ 2, 3 or 4 chambers Heart w/ 2, 3 or 4 chambers Respiration – gills & lungs Respiration – gills & lungs Closed circulatory system Closed circulatory system Endothermic or exothermic Endothermic or exothermic

The Fishes Water dwellers usually w/ gills, scales and fins Water dwellers usually w/ gills, scales and fins 3 main groups 3 main groups 1. Agnatha - Jawless: lampreys and hagfish 1. Agnatha - Jawless: lampreys and hagfish 2. Chondrichthyes : Cartilaginous fishes: Sharks, skates and rays 2. Chondrichthyes : Cartilaginous fishes: Sharks, skates and rays 3. Osteichthyes: Bony Fishes: Tuna, salmon and bass 3. Osteichthyes: Bony Fishes: Tuna, salmon and bass

Agnatha Agnatha – is a “super”class of the subphyla Vertebrata and of the phylum Chordata Agnatha – is a “super”class of the subphyla Vertebrata and of the phylum Chordata Greek “a” - without Greek “a” - without Greek “gnatha” - jaw Greek “gnatha” - jaw Called the Jawless Fishes - Hagfish & Lampreys Called the Jawless Fishes - Hagfish & Lampreys Characteristics Characteristics Some do not consider them a true fish because adults have no backbone only a notochord. Skeleton is cartilaginous Some do not consider them a true fish because adults have no backbone only a notochord. Skeleton is cartilaginous Marine & freshwater, parasitic or scavengers with external fertilization Marine & freshwater, parasitic or scavengers with external fertilization Eel-like bodies, with 2 brains !! & 4 hearts ( 1 main brachial heart & 3 accessory hearts pump blood to liver, kidneys & to the body!! Eel-like bodies, with 2 brains !! & 4 hearts ( 1 main brachial heart & 3 accessory hearts pump blood to liver, kidneys & to the body!! Round sucker-like mouth w/ teeth used to bore into the side of their host fish Round sucker-like mouth w/ teeth used to bore into the side of their host fish

Chondrichthyes Cartilaginous Fishes, they are true fish Cartilaginous Fishes, they are true fish Sharks, skates and rays Sharks, skates and rays Skeleton is cartilaginous, only teeth are “calcified” a few sharks have some of their cartilage calcified (different from “bone”) Skeleton is cartilaginous, only teeth are “calcified” a few sharks have some of their cartilage calcified (different from “bone”) Internal fertilization Internal fertilization Two chambered heart Two chambered heart Skates & rays have flattened wing-like bodies; some w/ whip-like tails & poisonous spines Skates & rays have flattened wing-like bodies; some w/ whip-like tails & poisonous spines Largest fish is the whale shark – reaching over 40 feet long & feeds on plankton Largest fish is the whale shark – reaching over 40 feet long & feeds on plankton

Chondrichthyes

External Shark Anatomy Ampullae of Lorenzini Males have 2 “claspers” medial to the pelvic fins to aid in fertilization, females do not have these.

Internal Shark Anatomy 18. Left lobe liver 19. right lobe liver. 20. Gall bladder 21. Stomach 22. duodenum 23. Ilium 30. Spleen 33. Bile duct 34. Testes 39. Heart

Osteichthyes Boney fish – salmon, trout, bass, perch, sardines, etc. Boney fish – salmon, trout, bass, perch, sardines, etc. Largest class of vertebrates Largest class of vertebrates boney skeletons with a boney gill plate - operculum boney skeletons with a boney gill plate - operculum Air Bladder adjusts the density of the fish in the water column Air Bladder adjusts the density of the fish in the water column 2 chambered heart 2 chambered heart Lateral line present in most – sense organ that can detect movement, pressure changes and vibrations in the surrounding water Lateral line present in most – sense organ that can detect movement, pressure changes and vibrations in the surrounding water

Boney Fish External Anatomy

Boney Fish Internal Anatomy

Can you identify these external structures?

Can you identify these internal structures?

That’s it for the fishes… Next up are the amphibians & reptiles