Fishes

chapter 24

fish scales

dermal origin

cyclostomata

jawless fish

gnathostomes

jawed fish

chondrichthyes

cartilaginous fishes- like sharks

osteichthyes

bony fish and tetrapods (four legs) like mammals

sarcopterygii

lobe-finned fish

actinopterygii

ray-finned fish

group myxini

hagfish

hagfish

marine, scavengers, predators, nearly blind, pore-like gills, secrete slime for defense

petromyzontida

lampreys

parasitic lamprey

attach to fish with sucker-like mouth. inject anticoagulant and suck fluids. sharp teeth, wound may be fatal, live 1-3 years.

nonparasitic lampreys

do not feed as adults.adigestive tract degenerates as adults. live a few months as adults.

ammocoete larave

blind, worm-like, filter-feeding juvenile stage of lampreys. live as suspension feeders. metamorphose into adults.

anadromous lamprey

species that hatch in freshwater, migrate to the ocean to grow into adults, and return to freshwater to spawn.

two subgroups of chondrichthyes

elasmobranchii- most species

holocephali- few species

chondrichthyes reproduction

fertilization is internal. oviparous, ovoviviparous, and viviparous species.

elasmobranchii

sharks, skates, and rays. found in coastal and pelagic waters.

streamlined fusiform body

a spindle-shaped, torpedo-like form that is wide in the middle and tapers at both ends, specifically adapted to minimize drag in aquatic or aerial environments

asymmetrical heterocercal tail

provides thrust and lift. a type of caudal fin where the vertebral column extends into a larger, elongated upper lobe, while the lower lobe is smaller.

placoid scales

reduce water turbulence

olfactory organs

“smell” prey

lateral line system

s a sensory system in fish and aquatic amphibians that detects water movements, pressure changes, and vibrations, aiding in navigation, hunting, and schooling

ampullae of lorenzini

specialized electroreceptor organs in cartilaginous fish (sharks, rays, skates) that detect faint electric fields, allowing them to locate prey, navigate, and communicate.

spiral valves in intestine

slows down passage of food, increases absorptive area

elasmobranch- rays

skates, stingrays, sawfish, manta rays, electric rays. bottom dwelling. dorsoventrally flattened

spiracles

small, paired, external opening used for breathing

holocephali: chimaeras

ratfish, ghostfish. flat plates instead of teeth. have operculum.

osteichthyes : bony fishes and tetrapods

96% of living fishes and all tetrapods. have bone that replaces cartilage. have lungs or swim bladder. o

operculum

increased respiratory efficiency.

actinopterygii- ray-finned fishes

heavy ganoid scales. bichirs, sturgeon

ganoid scales

cycloid, ctenoid scales

thin flexible scales

pharyngeal jaws

chewing, grinding, crushing

1,500 × 1,300

homocercal tail

symmetrical, for increased speed.

enameled scales

scales of sarcopterygii. protective layer

diphycercal tail

a type of fish caudal fin where the vertebral column extends straight to the tip, resulting in a symmetrical tail with equal upper and lower lobes

rhipidistian

a clade of lobe-finned fishes which includes the tetrapods and lungfishes.

caudal peduncle

the narrow, muscular region of a fish's body located between the end of the anal/dorsal fins and the base of the tail (caudal) fin.

regional endothermy

a specialized form of warm-bloodedness where marine animals maintain certain body parts—like muscles, eyes, or brains—at higher temperatures than the surrounding water

weberian ossicles

a set of small bones (claustrum, scaphium, intercalarium, and tripus) in freshwater fish (superorder Ostariophysi) that connect the swim bladder to the inner ear

operculum

a bony gill cover for breathing

ram ventilation

some sharks respire this way, they have to keep swimming to breathe

freshwater fish

gain water, loose salt

marine fish

loose water, gain salt

euryhaline fish

move between fresh and salt waters

estuaries- fluctuating salinity levels

anadromous

switch between salt and fresh water. come to freshwater to spawn. salmon.

viviparous

live birth- some sharks

producing living young instead of eggs from within the body

Ovoviviparous

produce eggs that develop and hatch inside the mother's body, resulting in live birth.

oviparous

laying eggs that develop and hatch outside the mother’s body

fish grow more rapidly in

warm water

otoliths

ear stones, show age. function as gravity and motion sensors.

rings on scales- circuli

show seasonal growth cycles