Final Flashcards
Specific Gravity of Freshwater and Saltwater
1.00 & 1.026
Specific Gravity of bone and muscle
2.0 & 1.055
What are two low-density fluids used to control buoyancy?
oils (lipids) & Salt-free fluids
5 ways fish reduce their sinking rate
- low density compounds
- Lifting surfaces
- Reduction in bone and muscle
- More cartilage
- Swim bladder
How does the opah create endothermy?
constant flapping of pectorals and minimized heat loss through counter-current heat exchangers in gills.
How do canal neuromasts function?
they detect differential pressure between their pores that leads to a fluid shift in the canal
what is the fluid in neuromast canals in chondrichthyes and bony fishes?
chondrichthyes: seawater
bony fishes: potassium rich mucus, endolymph
modified neuromasts that detect subtle electrical field changes
pit organs
how sensitive are shark’s electrosensors?
detect differential of 0.1 microvolt/cm (porbeagle shark sensitive to 0.001)
light sensitive cells on dorsal region of brain
pineal body
this area of the eye doubles light sensitivity by using reflective guanine crystals
the tapetum
which type of pigments don’t match the dominant backwelling light, and why?
cone pigments, because this increases the contrast between the background and lighter objects.
what is the key principal of animal colouration?
minimize detectability during predation and maximize it during display.
which pigment causes dark browns, dark reds, or black, and what produces it?
melanin. produced by the fish
what pigment causes bright colours, and what produces it?
carotenoids. produced by the fish’s food.
what is the role of the two nerve endings beside each chromatophore?
to release either epinephrine (contracts - pales) or acetylcholine (disperses - brightens colour))
how do nocturnal and diurnal fish differ in how they offset pigments?
nocturnal fish don’t offset pigments, diurnal do - have as many as 5 pigments (12 in guppy).
what is a large distinction between light propagation in terrestrial versus aquatic environments?
coloured light travels further in terrestrial environment
in what environment is disruptive colouration more useful?
the shallows
why are many deep fish red?
red light doesn’t penetrate far. black colour could be produced by melanin, but it is toxic.
how is uv colouration used?
as a high fidelity secret communication method.
how do fish use fluorescence (3)?
as intraspecific communication, camouflage in fluorescing environments, and to attract plankton prey.
what roles do directive marks play? (3)
- direct predator to less vulnerable area
- misdirect predator as to escape direction
- increase escape with a caudal strike
how can one differentiate advertisement from concealment?
- ontogenetic sequence for each sex
- age and size-specific mortality from each predator
- spectral sensitivity of predator and prey
- spectral distribution of the substrate at the depth and time where predation occurs.
- spatial geometry of interactions.
