Marine Amoeba Identification Guide
The forms of, from left: polypodial and lobose; monopodial and lobose; filose; conical; reticulose; tapering actinopods; non-tapering actinopods Amoebae move and feed by using pseudopods, which are bulges of formed by the coordinated action of pushing out the that surrounds the cell. The appearance and internal structure of pseudopods are used to distinguish groups of amoebae from one another. Species, such as those in the genus, typically have bulbous (lobose) pseudopods, rounded at the ends and roughly tubular in cross-section. Amoeboids, such as and, have slender, thread-like (filose) pseudopods. Emit fine, branching pseudopods that merge with one another to form net-like (reticulose) structures. Some groups, such as the and, have stiff, needle-like, radiating (actinopoda) supported from within by bundles of.
Shell of the Difflugia acuminata. To regulate, most freshwater amoebae have a contractile which expels excess water from the cell. This is necessary because freshwater has a lower concentration of (such as salt) than the amoeba's own internal fluids (). Because the surrounding water is with respect to the contents of the cell, water is transferred across the amoeba's cell membrane.
Without a contractile vacuole, the cell would fill with excess water and, eventually, burst. Marine amoebae do not usually possess a contractile vacuole because the concentration of solutes within the cell are in balance with the of the surrounding water. Amoeba phagocytosis of bacteria The food sources of amoebae vary. Some amoebae are predatory and live by consuming bacteria and other. Some are and eat dead organic material. Amoebae typically ingest their food by, extending pseudopods to encircle and engulf live prey or particles of scavenged material. Amoeboid cells do not have a mouth or, and there is no fixed place on the cell at which phagocytosis normally occurs.
Some amoebae also feed by, imbibing dissolved nutrients through formed within the cell membrane. Have reticulose (net-like) pseudopods, and many species are visible with naked eye The size of amoeboid cells and species is extremely variable. The marine amoeboid is just 2.3 to 3 in diameter, within the size range of many bacteria. At the other extreme, the shells of deep-sea can attain 20 cm in diameter. Most of the free-living freshwater amoebae commonly found in pond water, ditches and lakes are, but some species, such as the so-called 'giant amoebae' and, can be large enough to see with the naked eye.
Species or cell type Size in micrometres 2.3–3 8–15 (white blood cell) 12–15 12–40 15–60 30–152 220–760 700–2000 up to 5000 up to 000000000♠200 000 Amoebae as specialized cells and life cycle stages [ ]. Neutrophil (white blood cell) engulfing anthrax bacteria Some have amoeboid cells only in certain phases of life, or use amoeboid movements for specialized functions. In the immune system of humans and other animals, amoeboid pursue invading organisms, such as bacteria and pathogenic protists, and engulf them.
Amoeboid stages also occur in the multicellular fungus-like protists, the so-called. Both the plasmodial slime moulds, currently classified in the class, and the cellular slime moulds of the groups and, live as amoebae during their feeding stage. The amoeboid cells of the former combine to form a giant organism, while the cells of the latter live separately until food runs out, at which time the amoebae aggregate to form a multicellular migrating 'slug' which functions as a single organism. Other organisms may also present amoeboid cells during certain life-cycle stages, e.g., the gametes of some green algae () and pennate, the spores (or dispersal phases) of some, and the stage of and of. Of the pathogenic with ingested Some amoebae can infect other organisms, causing disease: • is the cause of, or amoebic dysentery. • (the 'brain-eating amoeba') is a fresh-water-native species that can be fatal to humans if introduced through the nose.
Amoebae - testate, in: Costello, M.J. Of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification.
Marine Amoeba Identification Guide
• can cause amoebic and in humans. • is the cause of (often fatal) • Amoeba have been found to the bacteria implicated in. Meiosis [ ] Recent evidence indicates that several Amoebozoa lineages undergo. Of genes employed in of sexual have recently been identified in the. These genes included,,,,, Mnd1,,. This finding suggests that the ‘’Acanthamoeba‘’ are capable of some form of meiosis and may be able to undergo sexual reproduction.