''Cystisoma '' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

amphipod Amphipoda () is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods () range in size from and are mostly detritivores or scavengers. There are more than 10,700 amphipod species cur ...

. It is the only member of the family Cystisomatidae within the Hyperiidea. The genus is noted for its nearly completely transparent body, adapted for life in low light waters.

Description

Gallery

''Cystisoma'' are characterized by unpigmented, transparent bodies which render them essentially invisible in water unless under precisely angled lighting. Only their eyes are pigmented. There is only a single pair of eyes which are large and directed upwards, being spread into a thin sheet on the upper surface of the head. This is likely an adaption of life in the ocean depths, where the only major light source is from above. Marine biologists at

Duke University Duke University is a Private university, private research university in Durham, North Carolina, United States. Founded by Methodists and Quakers in the present-day city of Trinity, North Carolina, Trinity in 1838, the school moved to Durham in 1 ...

and the Smithsonian analyzed the crustacean's shell and discovered that it was covered in microscopic spheres that significantly reduce reflected light, thus giving the organism an antireflective coating. The spheres are believed to be

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

due to their morphology and method of reproduction. Minute structures called nanoprotuberances were also observed on the ''Cystisoma'''s body, notably on the organism's legs. Researchers believe that they act as a buffer between light and the amphipod's body, significantly reducing surface reflection.

Size

''Cystisoma'' are the largest of hyperiids, reaching lengths over 100 mm.

Distribution

''Cystisoma'' inhabit the dim

epipelagic The photic zone (or euphotic zone, epipelagic zone, or sunlight zone) is the uppermost layer of a body of water that receives sunlight, allowing phytoplankton to perform photosynthesis. It undergoes a series of physical, chemical, and biological ...

and

mesopelagic The mesopelagic zone (Greek language, Greek μέσον, middle), also known as the middle pelagic or twilight zone, is the part of the pelagic zone that lies between the photic epipelagic and the aphotic bathypelagic zones. It is defined by light ...

zones. They can be found in all of the world's oceans. They appear to be freely swimming organisms and unlike other hyperiids, do not appear to be closely associated with

salp A salp (: salps, also known colloquially as “sea grape”) or salpa (: salpae or salpas) is a barrel-shaped, Plankton, planktonic tunicate in the family Salpidae. The salp moves by contracting its gelatinous body in order to pump water thro ...

Species

* ''Cystisoma fabricii'' Stebbing, 1888 * ''Cystisoma gershwinae'' Zeidler, 2003 * ''Cystisoma latipes'' (Stephensen, 1918) * ''Cystisoma longipes'' (Bovallius, 1886) * ''Cystisoma magna'' (Woltereck, 1903) * ''Cystisoma pellucida'' (Willemöes-Suhm, 1873)

References

External links

Cystisoma Eye
{{Taxonbar, from=Q10465209 Hyperiidea Amphipod genera Crustaceans by year of formal description Crustaceans described in 1842