Gromia sphaerica

Gromia sphaerica is a kind beschalter amoeba -like protozoans. They inhabit the deep sea and ocean floors are unusually large with a diameter of up to approximately 4 centimeters for protozoa.

Features

Gromia sphaerica are ball to grape -shaped, single chamber with a diameter 4.7 to 38 mm, averaging 15 mm were measured.

The translucent, sometimes slightly brownish, flexible outer shell is multi-layered: at the top is an extremely thin, granular layer, the cases a slightly thicker, fibrous support structure of proteins. This case is, unlike related species having only one or a few openings, occupied by a number of fine and evenly distributed over the outer shell pores. The outlet openings of the pores are each at the center of seen from above circular projection to the turn is a ring-shaped, slightly recessed courtyard. From the pore opening which is formed from the protoplasm, filopodischen pseudopodia emerge. Under the fibrous cap are the so-called "honeycomb membranes", a generic layer typical of many fragmentary documents by partitions of interconnected hexagonal cylinder.

Beneath the outer shell is a thin, dark green layer of protoplasm. Surrounded from the cell body cavity is empty or it can be found agglomerations of small faecal pellets ( Stercomata ). The faecal pellets are gray or brown, have a diameter of 10 to 20, sometimes up to 40 microns, and fill the entire cavity from.

Individual instructions indicate that Gromia sphaerica have only a cell nucleus, but this is not assured.

Dissemination

So far, populations of the species have been discovered in the Arabian Sea and in the Bahamas. Off the coast of Oman, they could be detected at depths from 1200 to 1600 meters, by the Pakistani coast up to 1800 meters depth and in the Bahamas at depths of 750-780 meters.

Gromia sphaerica occur on the ocean floors of the respective continental slopes in loose but not liquid sediments that are rich in nutrients such as phosphates, silicates and nitrogen. In these sediments, they are either embedded completely covered (Bahamas ) or partially open lying (Oman ). The surrounding water it contains relatively little oxygen (0.47 ml liter -1).

Way of life

Gromia sphaerica move slowly through the sediments, leaving it up to 50 centimeters long, deep and visible track. However, you do not move actively, but "eat" is probably equally forward: take the surrounding extremely nutrient-rich top layer of the sediment through their pseudopodia to digest it in the cytoplasm and transport them behind, resulting in a free space to the front, into which they roll until they can absorb sediment again. The digested sediments are excreted back down again, so as to form a narrow, raised track in the center of the groove.

The tracks thus produced show a great similarity with fossil traces of the Ediacaran fauna, which so far mostly multicellular organisms have been assigned. Due to similarities of the marks in terms of size and structure, and the existence of similar marks in the Paleoproterozoic, in which there was no multicellular life (eg in the Stirling Range Formation), it is considered possible that these traces at least in part also result from similar sized protozoa.

Occasionally, they form groups of two or three individuals.

System

The species was discovered in Collections of the RRS Discovery Cruise 211 on their October-November 1994, submit the coast of Oman and first described in 2000 by a team led by Andrew J. Gooday. Molecular genetic studies of morphologically poorly against each identifiable species of the genus confirmed Gromia sphaerica as an independent species and showed as next of kin of some species previously not formally described.