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Share the 4 chordate characters with lancelets and sea squirts Backbone, vertebral column, spine Series of hollow vertebrae Protects nerve cord (spinal cord) Bilateral symmetry endoskeleton. Phylum Chordata, subphylum Vertebrata. Lack: paired fins, scales, & well developed vertebrae
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Share the 4 chordate characters with lancelets and sea squirts Backbone, vertebral column, spine Series of hollow vertebrae Protects nerve cord (spinal cord) Bilateral symmetry endoskeleton Phylum Chordata, subphylum Vertebrata
Lack: paired fins, scales, & well developed vertebrae Hagfish (slime eels) Mucus for protection Feed on decaying flesh Lampreys Parasitic Anadromous Marine adults, breed in freshwater Agnatha (jawless fishes)
Sharks, rays, skates, & ratfishes Movable jaws of ventral mouth Paired fins Placoid scales Dentricles (same composition as teeth) Chondrichthyes (cartilagenous fishes)
Heterocercal caudal fin Two dorsal fins Paired pectorals 5-7 gill slits Many rows of teeth Oily liver Diverse examples: hammerhead, sawfish, thresher, whale sharks Sharks
Flattened Demersal 5 prd ventral gill slits Expanded pectorals Rays vs. skates rays: reduced or no dorsal fin Stingrays Venomous defensive spine Electric rays Upto 200 volts for defense and predation Ratfishes (chimaeras) Deep, bottoms, long skinny tail Paired (pelvic) & unpaired (forehead) male claspers for copulation & holding female --seen in rabbitfish Rays, Skates, & Ratfishes
Swim bladder Operculum (gill cover) Homocercal tail Scales of bony origin Smooth cycloid Spiny ctenoid Osteichthyes (bony fishes)
Diverse morphologies, habits, & behaviors Tear flesh; most swallow whole by: snout; protrusible; beak-like; large filtering mouths Undulating entire body; muscular caudal flex; fins only; caudal fin only
Mouth Esophagus Stomach Intestine w/ increased SA spiral valve pyloric caeca Pancreas Digestive enzymes Liver Bile to breakdown fats cloaca or anus Digestive systems
Circulatory system: 2 chambered heart (“one way flow”) …atrial chamber to gills, “fresh” blood to tissues, back to ventricle chamber
a.) Water across gills through mouth and spiracles in cartilagenous fishes • Why are spiracles significant? b.) Opercula of bony fishes opens and closes with mouth; greater suction; more efficient
High surface area from many folds or lamellae of gill filaments The water : blood relationship is in a counter-current orientation -- enhances diffusion higher [Oxygen] in water than blood Gill function and diffusion of gas
a.) concentrated urea prevents dehydration to deal with excess salts; excrete via rectal gland b.) to compensate for tissue water loss: drink sea water, conserved by kidneys, excrete urine Osmosis
Internal fertilization w/specialized copulatory structures External fertilization Broadcast spawning Millions of eggs released as part of plankton Some fishes deposit eggs on bottoms Some bury in sandy shores Unique examples: Male carriers e.g. At Birch aquarium Oviparous Eggs released, fertilized, developed externally, lots of yolk Viviparous Internal development, direct nourishment; birth live young Ovoviviparous Internal egg development; yolk; birth live young Fish reproduction & development