exam3 Flashcards
(164 cards)
nekton
fish that can swim against currents in water column
nekton constraints
high Re
-inertial dominate viscous forces
-must minimize pressure drag for fast continual motion
nekton principal members
cephalopods, fish, mammals, sea birds, reptiles
cephalopoda
belong to phylum Mollusca, includes octopus, squid, cuttlefish, nautiluses
characteristics of cephalopods
generally carnivorous,
high developed nervous system with excellent vision, color change,
internal fertilization
chromatophores
pigment cells used to color change and camoflauge
buoyancy using cuttlebone
made of calcium carbonate, many internal chambers that can have gas to liquid ratio regulated to help move up and down the water column
hypnome
cuttle fish use their color changing abilities to confuse or lore prey into them before striking
fish
aquatic vertebrates with gills, fins, and streamline body shapes, very diverse group
osteichthyes
bony fish with true bone skeletons, very diverse, teeth fixed in jaws, single gill opening
chondricthyes
cartilaginous fishes-skates, sharks, rays. replaceable teeth rows, 5 or more gill slits
swimming vs body form
long and narrow-acceleration specialized, round coin/shapes-maneuvering specialist
swimming mechanism
undulation of the body to move- more undulations in eels, tail concentrated in sharks and tuna
oxygen use
Oxygen from water is picked up through mouth and over exposed gills when swimming. more oxygen in water than in gills so diffuses into gills
gill structure
feathery with lots of capillaries and surface area to absorb most oxygen.
countercurrent exchange
blood flows in the opposite direction to the water that flows over gills, gives most favorable gas gradient throughout the body
swim bladder
in most boney fish to regulate buoyancy, can inflate/deflate with oxygen gas to move up or down the water column
gas gland
flexible sac located in dorsal portion of body that controls gas for buoyancy
rete mirabile
intertwined capillaries and veins to help with countercurrent exchange to retain oxygen near gas gland
suction feeding
most common, rapid expansion of mouth to Greate pressure gradient to pull fish into oral cavity
ram feeding
fish opens mouth and swims forward, engulfing prey along with the water surrounding it. ex.whale sharks
suspension feeding
aka filter feeding, feed on particles suspended in the water, don’t swim but rather rely on water movement to bring particles into mouth
gill arch and rakers
gill rakers are on opposite sides of gill arch as the filaments. Used to keep prey in mouth instead of falling out through gills with water
lateral line system
sensory system in fish that detects movement in water thru neuromasts along lateral line, lets them gauge where they are in the water and detect predators