Date post: | 21-Dec-2015 |
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The outcome of a predator/prey interaction depends on:
Sighting distance = the maximum distance at which a prey animal is detected by an animal relying on visual cues
Transparency allows:a) Prey with short sighting distance reduce their
encounters with visually orienting prey
c) Raptors to get within striking distance before being detected
b) Ambush predators with short sighting distance to increase chances of entangling prey before being detected and avoided
UV (~320nm)
Predator solutions to catching transparent prey…
1. UV visionfound in mantis shrimp,
cladocerans, copepods, decapods, horseshoe crabs, and even a polychaete worm!
2. Polarization visionlight is polarized when it enters water
Unpolarized light Polarized light
http://oceanexplorer.noaa.gov/explorations/04deepscope/logs/aug12/aug12.html
The Great Barrier Reef taken through a polarizing filter held in front of the camera horizontally, vertically, and at 45º.
The fourth image is coded with color to show that much of the water is horizontally polarized (coded here as red). By Justin Marshall and Tom Cronin
http://oceanexplorer.noaa.gov/explorations/04deepscope/background/polarization/polarization.html
Blue whale – feeding• ‘gulp’ feeders – sieve plankton through sheets of baleen• ~ 3,600 kg drill/day for about 120 days
atrium
Branchial baskets For feeding & locomotion
Shared tunic
Direction oflocomotion
Water jet
(Ph. Urochordata – Cl. Thaliacea)
Larvacean
(Ph. Urochordata – Cl. Larvacea)
Tadpole larva
tailtail
pharynx
water current
water current
pharynx
Larvacean in its mucous house
Mucous house:
• secreted by the trunk epidermis
Water:
• food is concentrated and passed to the pharynx
• Filtered water exits, jetting the house forward.
Copepods ‘shape’ their fluid motion either to advertise or conceal themselves in the plankton. HOW does this work?
Imaged with Schlieran photography
2. When it ‘hovers’ it creates a laminar feeding current using fine setae on the second antennae. this disturbance appears as lines of
equal speed of fluid: these are called isotachs.
1. As the copepod moves through water it creates a fluid disturbance.
“Organizing the fluid medium”:
3. The sensors on the antennae detect changes in speed of the isotachs in three directions and so the copepod can detect water-borne signals in 3 dimensions:
x, y, z and a fourth dimension, time.