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Sessile animals can move via external forces (such as water currents), but are usually permanently attached to something. Organisms such as corals lay down their own substrate from which they grow. Other animals organisms grow from a solid object, such as a rock, a dead tree trunk, or a human-made object such as a buoy or ship's hull.
All cells can be considered motile for having the ability to divide into two new daughter cells. [1] Motility is the ability of an organism to move independently using metabolic energy. This biological concept encompasses movement at various levels, from whole organisms to cells and subcellular components.
As with all Cnidarians, these organisms have a complex life cycle including a motile planktonic phase and a later characteristic sessile phase. Hexacorallia also include the significant extinct order of rugose corals.
Sessility, or sessile, may refer to: Sessility (motility) , organisms which are not able to move about Sessility (botany) , flowers or leaves that grow directly from the stem or peduncle of a plant
A great majority are marine (salt-water) species, ranging in habitat from tidal zones to depths exceeding 8,800 m (5.5 mi), though there are freshwater species. All adult sponges are sessile, meaning that they attach to an underwater surface and remain fixed in place (i.e., do not travel). While in their larval stage of life, they are motile.
Non-motile species lack the ability and structures that would allow them to propel themselves, under their own power, through their environment. When non-motile bacteria are cultured in a stab tube, they only grow along the stab line. If the bacteria are mobile, the line will appear diffuse and extend into the medium. [90]
One large and sessile, one small and motile (oogamy). The larger sessile megagametes are eggs (ova), and smaller motile microgametes are sperm (spermatozoa, spermatozoids). The degree of motility of the sperm may be very limited (as in the case of flowering plants) but all are able to move towards the sessile eggs.
The majority of animals are motile. Motile animals can disperse themselves by their spontaneous and independent locomotive powers. For example, dispersal distances across bird species depend on their flight capabilities. [24] On the other hand, small animals utilize the existing kinetic energies in the environment, resulting in passive movement.