Massisteria marina ist ein heterotropher Flagellat aus der Gruppe der Cercozoa. Er ist die einzige Art der Gattung Massisteria und Familie Massisteriidae, und gehört zum Stamm Cercozoa. Sie ist in Meeren weit verbreitet und ernährt sich von Bakterien.
Die Zellen sind abgeflacht und tragen zwei kurze, nicht aktive Geißeln, die im amöboiden Stadium auf der Zelloberfläche aufliegen. Die Zellen bilden sehr dünne, verzweigte Pseudopodien, die kleine Extrusomen und Mikrotubuli enthalten.
Sie besitzen einen recht komplexen Zellzyklus, der Amöben, aktiv schwimmende zweigeißelige Zellen und Plasmodien umfasst. Zysten sind nicht bekannt.
Massisteria wurde früher zu den Cercomonadida gestellt. Molekulargenetischen Untersuchungen zufolge gehört sie jedoch definitiv nicht in diese Gruppe. Verschiedene Arbeiten stellen sie in unterschiedliche Gruppen der Cercozoa, jeweils mit geringer statistischer Abstützung. Adl et al.[1] stellten sie daher incertae sedis in die Cercozoa. Bass et al. haben sie 2008 als eigene Familie Massisteriidae in die Klasse Granofilosea gestellt.[2]
Massisteria marina ist ein heterotropher Flagellat aus der Gruppe der Cercozoa. Er ist die einzige Art der Gattung Massisteria und Familie Massisteriidae, und gehört zum Stamm Cercozoa. Sie ist in Meeren weit verbreitet und ernährt sich von Bakterien.
Massisteria marina is a species of small marine phagotrophic protists that normally feed on bacteria. Individuals live associated with sediment particles and suspended detritus in litoral or marine waters. It is found at marine sites all around the world. Its predominantly sedentary lifestyle was a discovery that challenged the concept of bacterivorous protists as constantly active hunters, and its permanent association with detritus particles is uncommon among flagellates.[2]
M. marina are unicellular amoeboflagellates composed of a flattened irregular star-shaped[2] cell body measuring 3–9 μm in diameter, pressed against the substrate, with several (2 to 10) thin branching filamentous pseudopodia, extrusomes close to the substrate, and two short inactive flagella that measure 4–6 μm. The arrangement of their pseudopodia are reminiscent of freshwater species Gymnophrys cometa, which usually has only two pseudopodial trunks but more can arise.[1]
M. marina cells often lie within detritus particles, making them difficut to see unless they are left undisturbed for several minutes. The cells frequently appear in clusters, and the pseudopodia of adjacent cells sometimes join.[1] Electron microscopy reveals that adjacent cells in these clusters often share a common, continuous cytoplasm.[2]
M. marina are usually sedentary and feed through their pseudopodia while their flagella are inactive. However, under adverse conditions, they switch to a swimming non-feeding phase: the pseudopodia are reabsorbed and the flagella become active, with one flagellum directed forward while the other trails behind.[1][2]
M. marina is extremely widespread and abundant. It has been isolated with great frequency from littoral, oceanic and deep waters from tropical and temperate regions.[2] It has been found in Halophila beds in Fiji, Queensland, Panama, Hawaii, Rio de Janeiro, United Kingdom, Ireland, Denmark, and in sedimenting detritus at oceanic sites.[1]
Massisteria marina is a species of small marine phagotrophic protists that normally feed on bacteria. Individuals live associated with sediment particles and suspended detritus in litoral or marine waters. It is found at marine sites all around the world. Its predominantly sedentary lifestyle was a discovery that challenged the concept of bacterivorous protists as constantly active hunters, and its permanent association with detritus particles is uncommon among flagellates.
