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Fish Morphology. Classification Scheme of the Vertebrates. Phylum Chordata Subphylum Vertebrata Class Agnatha Class Chondrichthyes Class Osteichthyes Class Amphibia Class Reptilia Class Aves Class Mammalia. Chordate Characteristics. Chondrichthyes (370). Placoderm
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Classification Scheme of the Vertebrates Phylum Chordata Subphylum Vertebrata Class Agnatha Class Chondrichthyes Class Osteichthyes Class Amphibia Class Reptilia Class Aves Class Mammalia
Chondrichthyes (370) Placoderm (395-345) Ostracoderm (510-=350 mybp) (360) Osteichthyes (395) lamprey & hagfish
Jaw Development agnathostome gnathostome 1st appeared 400 mya
Basic Anatomy Class Agnatha • Possess medial nostril, medial fins, notocord rather than vertebral column • 7 or more pr gill pouches present • Light sensitive pineal eye • Fertilization external • Cartilaginous skeleton • Lack jaws, paired fins, scales • GI track w/out stomach • Lampreys and hagfish • 100 species
Class Agnatha Lamprey ammocoetes
Class Agnatha Hagfish
Basic Anatomy Class Chondrichthyes Sharks, skates, rays
Basic Anatomy Class Chondrichthyes Sharks, skates, rays • Posses jaws with teeth, cartilaginous skeleton, paired fins • Scales (denticles) have same origin and composition as teeth • Possesses 5-7 gills • Spiral valve intestine • Ureoosmotic strategy • Electroreception • Lateral line • No swim bladder • Heterocercal tail • Relatively unchanged (480 mybp)
Basic Anatomy Class Osteichthyes
Basic Anatomy Class Osteichthyes • Posses jaws with teeth, bony skeleton, paired fins • 4 paired gill arches covered by operculum • Intestine- simple, no spiral valve • Swim bladder • Lateral line • Homocercal tail • Scales- cycloid, ctenoid
Internal Anatomy anus
Basic Anatomy Latimeria • Swim bladder modified to lungs • Paired appendages • May have given rise to terrestrial tetrapods • Bony head • Scales and teeth
Fish Adaptations and Life Styles • General Life Style Categories • a. pelagic cruisers • occurring in water column far away from the bottom (benthic) environment • often referred to as "blue water" • includes tuna, billfish, blue sharks, mackerel sharks (great whites and mako sharks)
b. demersal • bottom-associated fishes, but not usually sitting on the bottom • rely on the benthic environment as a source of food, place to reproduce, and/or place of refuge, etc. • includes most reef fishes (e.g., butterfly fishes, surgeon fishes, wrasses, parrot fishes, etc.)
c. benthic • bottom-dwelling fishes that spend the majority of time sitting on the bottom • includes flatfishes, lizard fishes, many scorpion fishes, many hawkfishes, gobies, etc.
Body shape 1) fusiforma) = torpedo-shaped b) allows minimal drag while swimmingc) best shape for a pelagic cruise tuna
2) compressed • laterally flattened (e.g., butterflyfishes & surgeonfishes) • allows for maneuverability in surge environments • useful for demersal fishes that hover above the reef • exception seen in flatfishes that lie on one side of the body as benthic fishes
3) elongated or attenuated • long body (e.g., trumpetfish, cornetfish, eels) • seen in demersal fish that either hover motionless in the water) • seen also in benthic fishes (e.g., eels) that hide in holes in the reef
4) depressed • dorso-ventrally flattened (e.g., frogfishes, scorpionfishes & gobies) • broad ventral surface facilitates resting on the bottom • seen in many benthic fishes
Body Coloration • 1) source of color • pigment color - chromatophores for yellows, reds, oranges, browns, & blacks • structural color - iridophores (reflection) & light refraction for blues, silvers, & rainbows
2) patterns • a) countershading • dark blue or black dorsally, white or silvery ventrally • results in blue water "camouflage“ • observed most frequently in pelagic cruisers
b) camouflage • matching the background coloration • usually involves having irregular dark blotches and spots • typically seen in benthic fishes, especially benthic ambush predators (e.g., frogfishes, gobies, & many scorpionfishes) • some fishes (e.g., flatfishes) may exhibit rapid color changes in response to different backgrounds
b) camouflage • 5) matching downwelling light Hatchet fish Cookie cutter shark
c) disruptive coloration 1) color pattern breaks up the silhouette of the fish 2) may involve dark bars across the eye and tail region 3) seen in many demersal fishes such as butterfly fishes
d) bars and stripes 1) bars are vertical (e.g., manini) 2) stripes are horizontal (e.g., ta'ape) 3) seen frequently in schooling demersal fishes 4) may confuse potential predators by making it difficult to select individual prey from the school
e) misdirection 1) false eye spots, etc. 2) observed in many demersal butterfly fishes
f) advertising coloration 1) bright, obvious color patterns 2) possible functions a) advertising a cleaning station (e.g., cleaner wrasses) b) advertising a warning (e.g., nohu) c) advertising for mates (e.g., male parrotfishes) Hawaiian cleaner wrasse Nohu
g) mimicry 1) imitating other creatures 2) seen in a few demersal and benthic fishes 3) examples a) blenny (Aspidontus taeniatus) mimics cleaner wrasses b) shortnose wrasse mimics Potter's angel which sports a defensive spine
g) mimicry 4) leafy sea dragon (Australia)
h) uniform red coloration • most often observed in deep-dwelling or night active demersal fishes • examples include opakapaka, oweoweo, menpachi, & squirrelfishes
i) noctural versus diurnal color changes j) male versus female color differences k) juvenile versus adult color differences Dragon wrasse Stoplight parrotfish Bluehead wrasse
Fish Anatomy and Physiology
Types of Fins • The source of propulsion for virtually all fish comes from: • Undulation of the body • Paired Fins: • Pectoral • Pelvic • Unpaired Fins: • Caudal • Dorsal • Anal • A combination of the above
Anguilliform swimming (Undulation)
Anal Fin Propulsion Black ghost knifefish
Dorsal fin Bowfin Sea horse Knifefish
Pectoral Fin Frogfish
Hydrodynamics: Effects of shape on drag Disk Sphere teardrop Laminar flow and turbulence
Slowest Fish Ewa Blenny 0.5 mph