.JPG)
Sessility, a property of certainanimals, is a lack of self-locomotion. Sessile animals do not have naturalmotility, and are immobile unless there are external forces (such as water currents). Usually, sessile animals are permanently attached to a solid object, such as a rock, a dead tree trunk, or a human-made object such as a buoy or ship's hull.[1] Organisms such ascorals lay down their ownsubstrate from which they grow.
Biological sessility differs from the botanical concept ofsessility, which refers to an organism or biological structure attached directly by its base without a stalk.
Sessile animals typically have a motile phase in their development.Sponges have a motilelarval stage and become sessile at maturity. Conversely, manyjellyfish develop as sessilepolyps early in their life cycle. In the case of thecochineal, it is in the nymph stage (also called the crawler stage) that the cochineal disperses. The juveniles move to a feeding spot and produce long wax filaments. Later they move to the edge of the cactus pad where the wind catches the wax filaments and carries the tiny larval cochineals to a new host.
Many sessile animals, including sponges,corals andhydra, are capable ofasexual reproductionin situ by the process ofbudding. Sessile organisms such asbarnacles andtunicates need some mechanism to move their young into new territory. This is why the most widely accepted theory explaining theevolution of alarval stage is the need for long-distance dispersal ability. BiologistWayne Sousa's 1979 study in intertidal disturbance added support for the theory of nonequilibrium community structure, "suggesting that open space is necessary for the maintenance of diversity in most communities of sessile organisms".[2]
Clumping is a behavior in sessile organisms in which individuals of a particular species group closely to one another for beneficial purposes, as can be seen incoral reefs and cochineal populations. This allows for faster reproduction and better protection from predators.[3]
Thecircalittoral zone ofcoastal environments andbiomes are dominated by sessile organisms such asoysters.Carbonate platforms grow due to the buildup of skeletal remains of sessile organisms, usuallymicroorganisms, which induce carbonate precipitation through their metabolism.
In anatomy and botany,sessility refers to an organism or biological structure that has nopeduncle or stalk. A sessile structure has no stalk.
See:peduncle (anatomy),peduncle (botany) andsessility (botany).
Authority control databases: National |
|---|