Lecture 16 Flashcards
(32 cards)
where do most marine organisms live in the water? why?
Neritic zone where it is well-lighted and epipelagic zone where food is abundant
what is the neritic zone?
on the continental shelf
what is the oceanic zone?
after the continental shelf, open waters
what is the intertital zone?
before the continental shelf drop, beach
what are the levels of the water column? from top to bottom
Epipelagic, Mesopelagic, Bathypelagic, Abyssopelagic, Hadal
what wavelength/color penetrates the water column the best?
blue-green, 470nm
what is bioluminescence?
producing own light from biochemical reaction
voluntary or involuntary
what is fluorescence?
involuntary light that happens when organism is hit with UV light
where do bioluminescent fishes typically live?
in aphotic zone
what is bioluminescence used for?
light to see, communication, facilitate predation (lure), escape predators, counter illumination
what are the characteristics of deep sea fishes? why do they have these characters?
photophores to see/communicate, dagger-like teeth to they can grab any prey they come across, distensible stomachs to they are able to eat whatever prey they come across
what are the 5 deep sea physical factors that deep sea fishes need to overcome?
pressure, temperature, space, food, light
how does pressure increase as you go down the water column?
increases by 1atm/10m
how do deep sea fishes overcome dramatic increase in pressure?
increase swim bladder rete miracle to increase ability to regulate buoyancy
multiple evolutions of physoclistous swim bladder
multiple losses of swim bladder (at a certain pressure, you need a huge swim bladder, so they lose it altogether because the one they can have in their body is useless)
what is the thermocline?
level at which there is greatest change in water
what is the water like above and below the thermocline?
above = mixed, variable surface water, relatively warm
below= cold, dense, doesn’t mix very much
how do deep sea fishes overcome drop in temperature?
vertical migrations
why is space an issue for deep sea fishes?
bathypelagic zone is the largest habitat on earth, and fishes aren’t abundant, so they can’t find each other easily
what type of sexual dimorphisms do deep sea fishes have to overcome the lack of other conspecifics and abundant space?
photophore arrangements/flashing pattern
males with larger sound producing organs
males more mobile (more red muscle)
well developed olfactory lamellae and lobes
well developed eyes
parasitic (anglerfish)
why is food an issue in the deep sea? where does it come from?
it is very scare
comes from photic zone or deep sea vents
how do mesopelagic fishes combat the lack of food in deep sea?
have diurnal migration of about 700m
why is light an issue in the deep sea?
doesn’t penetrate the water column easily
what color is bioluminescence normally? why?
blue, 470nm, that is what color penetrates the water column the best
fishes’ eyes are tuned to this color
what percentage of deep sea fishes are bioluminescent?
75%
