Lecture 8 - Sensory Adaptations and Bioluminescence Flashcards
What is chemosensitivity?
adaptation for smell
Benthic and near-benthic spps rapidly arrive at bait
Pelagic - absence of turbulence = scent trail
Ways of detecting fluid movement past an organism
Mechanoreception
- lateral line organs of fishes
- sensory hairs and long antennae of crustaceans
Which fishes have the most developed mechanoreception?
Well developed in midwater and near bottom fishes
Bathypelagic and deeper fishes have prominent lateral line organsd
Which light is transmitted best in clear water?
Blue light (~470 nm)
Why is bioluminescence close to the wavelength of blue light?
(~470 nm)
- transmit further
- matches downwelling light for counterillumination
Light penetration in open ocean
blue light penetrates furthest
Light penetration in coastal waters
green/yellow light penetrates furthest
Why is red coloration just as good as black in the deep ocean?
Since blue light is predominant, red objects show up as black because there is no red light to be reflected by the red pigments in the red spps
What do fish use for their coloration?
Melanins, which tend to be brown or black
What do crustaceans use for their coloration?
Carotenoids, which by themselves, without proteins, are red and orange.
Eyes of deep water fish are more sensitive to ______ than freshwater fish
blue light
fresh water fisher see longer wavelengths
Why deep-sea animals have eyes with maximum absorbance around blue light?
So they can see bioluminescence and downwelling celestial light
(more adapted to see bioluminescence)
Which fish use red photophores to detect red light?
Malacosteid fishes
When do animals bioluminescence?
When disturbed
Visual adaptations
- Match color sensitivity to color of light received
- Use pigmented lenses
- Increase sensitivity to light (detection over sensitivity)
- Reduced landscape viewing, increased ability to detect spots
How do fishes match color sensitivity to color of light received?
blue absorption maxima
How do fishes use pigmented lenses?
use yellow lenses to discriminate between downwelling light and bioluminescence
How do fishes increase sensitivity to light?
Rod only retinas
Banked rods (multiple layers) in retinas
Longer rods
Reflecting tapetum of matched color behind rods
Rods linked via neurons to function as a single receptor
How do fishes reduce landscape viewing and increase their ability to detect spots?
Densely packed rods in foveae of eye (in retina)
Reduced eye size
Often telescopic eyes
How do crustaceans improve their eyesight?
As they go deeper, individual rods become packed and lose their screening pigment
What is Bioluminescence?
Form of chemiluminescence where a substrate and enzyme produce light
Proposed explanations for bioluminescence
Vision Lure Startle/decoy Counterillumination Burglar alarm Communication Warning pattern Bacteria
4 luciferins of most bioluminescence
Luciferin
Aldehyde
Luciferase
Photoprotein
Who uses Bacteria for their bioluminescence?
Fish (including anglerfishes), pyrosomes, squid
