Nekton Flashcards
Crustacea Decapoda
crabs and lobsters
Mollusca bivalvia
scallops
Mollusca cephalopoda
nautiluses, squids and octopods
fishes are not a formal
taxonomic group
cartilaginous fishes
sharks, rays, chimaeras
teleosts
bony fish
reptilia, squamata
lizards and snakes
reptilia: testudines
marine/sea turtles
reptilia: crocodilia
crocodiles
reptilia: aves
birds!!!!! <3 <3
Mammalia: sirenia
manatees and dugongs
Mammalia: Cetacea
whales
catacea: mysticeti
baleen whales
catacea: odontoceti
toothed whales
Mammalia: pinnipedia
seals, walruses
Pinnipedia: odobenidae
walrus
Pinnipedia: otariidae
eared seals
Pinnipedia: phocidae
earless seals
Mammalia: ursidae
polar bears
Mammalia: mustelidae
sea otter
fish life cycle Atlantic salmon
spawn in fresh water, eggs develop through multiple larval stadia, smolts migrate to sea, develop as adults and return to fresh water for spawning.
migration: distributional snapshots
check group, but don’t know what happened in the time in between, or if it’s the same group. –> fish catches
migration: banding tag-recapture
same individuals, but some individuals may disappear –> tag with identifier
Telemetry
measure individual animal movements –> electronic tag which emits info
life-cycle trackers
track life cycle of individuals –> stable isotope or otolith analysis
diadromous
migration between fresh and marine water
catadromous
adults migrate ‘down’ to sea, spawn at sea, juveniles migrate to fresh water. like paling!!
anadromous
adults migrate ‘up’ to fresh water, spawn there, juveniles move back to sea. like salmon!!
oceanodromous
fish that migrate wholly in the sea to spawn, like haring!! or tuna!!!
no parental care
80% of fish species. produce numerous eggs –> high mortality but sufficient survival.
parental care
20%, only lay a few eggs. ensure survival by guarding
whale calving and impregnation
in warm water. weaning and gestation in cold water
Re < 1
viscosity dominant
Re > 1
inertia is dominant
muscle fibers of fish are not
parallel along the body axis, they lay like a coil
white muscles
anaerobic, fast contraction and powerful, but relatively quickly fatigue. mostly for special manoeuvres like escapes
red muscles
aerobic, slow contraction and less powerful but long endurance!
tuna have red muscle fibers closer to core, why?
endothermic species: inside of body warmer than external temperatures. red muscle becomes more efficient with higher temperature
hypocercal tail
lower fin longer –> can still generate power with under tail when upper part is out of the water. flying fish.
epicercal
upper ion higher: sharks can hit fish
homocercal
equal in shape
pelagic fish tail
homocercal
benthic fish
assymetric fin, heterocercal
aspect ratio of fin
measure of how long and slender a fin is from fin root to tip. higher aspect ratio fins have lower drag and higher lift.
aspect ratio fin formula
S^2/A
Caudal keel
to minimize resistance
well streamlined body combines
low drag with largest possible volume. 0.23
name why bluefin tuna is so well stramlined
small frontal area, teardrop shape, streamlined and smooth body, no braking objects sticking out.
box fish swim with
fins only
shoaling
any group of fish that stay together for social reasons
schooling
if the group is swimming in the same direction in a coordinated matter
advantages of schooling
confuse predators, easier to find a mate, social interaction, reduce cost of swimming because of hydrodynamic advantages, foraging advantages –> 200 eyes see more than 1
bulk filter feeding
get a big mouthful of water and filter it
suction feeding in fishes
mouth opened with opercular plates closed, branchiostegal membrane is lowered + abduction of opercular, mouth closes.
cranial kinesis
movement of skull bones
premaxilla
protrusion of mouth –> brings mouth closer to the predator
pharyngeal jaws
second set of jaws in mouth
nekton uses which kind of swimming?
undulatory swimming
