Editing Antarctic krill (section)

===Bioluminescence===
[[File:Bioluminescencekils.jpg|thumb|Watercolour of bioluminescent krill]]
Krill are often referred to as ''light-shrimp'' because they emit light through [[Bioluminescence|bioluminescent]] organs. These organs are located on various parts of the individual krill's body: one pair of organs at the [[eyestalk]] (cf. the image of the head above), another pair  are on the hips of the second and seventh [[thoracopod]]s, and singular organs on the four [[pleonsternite]]s. These light organs emit a yellow-green light periodically, for up to 2–3&nbsp;s. They are considered so highly developed that they can be compared with a flashlight. There is a concave reflector in the back of the organ and a lens in the front that guide the light produced. The whole organ can be rotated by muscles, which can direct the light to a specific area. 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 [[Shoaling and schooling|schooling]] at night.

The krill's bioluminescent organs contain several fluorescent substances. The major component has a maximum [[fluorescence]] at an excitation of 355&nbsp;[[Nanometre|nm]] and emission of 510&nbsp;nm.<ref name="HS01">{{cite conference |author1=H. Rodger Harvey |author2=Se-Jong Ju |url=http://www.ccpo.odu.edu/Research/globec/3sciinvest/harvey.htm |title=Biochemical determination of age structure and diet history of the Antarctic krill, ''Euphausia superba,'' during austral winter |conference=Third U.S. Southern Ocean GLOBEC Science Investigator Meeting |location=Arlington |date=10–12 December 2001}}</ref>

[[File:Caridoid escape reaction.gif|thumb|Lobstering krill]]