''Cystisoma '' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

of amphipod. It is the only member of the family Cystisomatidae within the

Hyperiidea The Hyperiidea are a suborder of amphipods, small aquatic crustaceans. Unlike the other suborders of Amphipoda, hyperiids are exclusively marine and do not occur in fresh water. Hyperiids are distinguished by their large eyes and planktonic hab ...

. 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 and the Smithsonian analyzed the crustacean's shell and discovered that it was covered in microscopic spheres that significantly reduce

reflected light Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves. The ' ...

, thus giving the organism an

antireflective coating An antireflective, antiglare or anti-reflection (AR) coating is a type of optical coating applied to the surface of lenses, other optical elements, and photovoltaic cells to reduce reflection. In typical imaging systems, this improves the effic ...

. The spheres are believed to be

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...

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, 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 pro ...

and

mesopelagic The mesopelagic zone (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, and begins a ...

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

salps A salp (plural salps, also known colloquially as “sea grape”) or salpa (plural salpae or salpas) is a barrel-shaped, planktic tunicate. It moves by contracting, thereby pumping water through its gelatinous body, one of the most efficient ...

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 Amphipoda Crustaceans by year of formal description Crustaceans described in 1842