Difference between revisions of "Antarctic krill"
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===Bioluminescence=== | ===Bioluminescence=== | ||
Krill are often referred to as ''light-shrimp'' because they can emit light, produced by | Krill are often referred to as ''light-shrimp'' because they can emit light, produced by bioluminescent organs. These organs are located on various parts of the individual krill's body: one pair of organs at the eyestalk, another pair on the hips of the second and seventh thoracopods, and singular organs on the four pleonsternites. These light organs emit a yellow-green light periodically, for up to 2–3 seconds. They are considered so highly developed that they can be compared with a torchlight: a concave reflector in the back of the organ and a lens in the front guide the light produced, and the whole organ can be rotated by muscles. The function of these lights is not yet fully understood; some hypotheses have suggested they serve to compensate the krill's shadow so that they are not visible to predators from below; other speculations maintain that they play a significant role in mating or schooling at night. | ||
The krill's bioluminescent organs contain several fluorescent substances. The major component has a maximum | The krill's bioluminescent organs contain several fluorescent substances. The major component has a maximum fluorescence at an excitation of 355 nanometers. | ||
===Escape reaction=== | ===Escape reaction=== | ||
Krill use an | Krill use an escape reaction to evade predators, swimming backwards very quickly by flipping their rear ends. This swimming pattern is also known as "lobstering". Krill can reach speeds of over 0.6 meters per second. | ||
==Geographic distribution== | ==Geographic distribution== |