Sessile
From Wikipedia, the free encyclopedia
Sessile is a word with two distinct meanings:
[edit] In botany
In botany, sessile means "without a stalk", as in flowers (pedicle) or leaves(petiole) that grow directly from the stem or Peduncle.
[edit] In zoology
In zoology, sessile organisms are those which are not able to move about. They are usually permanently attached to a solid substrate of some kind, such as a rock, or the hull of a ship in the case of barnacles. Corals lay down their own substrate.
Sessile organisms typically have a motile phase in their development. Sponges have a motile larval stage, which becomes sessile at maturity. In contrast, many jellyfish develop as sessile polyps early in their life cycle. Many sessile animals, including sponges, corals, and hydra, are capable of asexual reproduction in situ by a process of budding.
Clumping is a behavior in an organism, usually sessile, in which individuals of a particular species group close to one another for beneficial purposes.
