The statocyst is a balance organ present in some aquatic
invertebrates ( Cnidarians, Ctenophores, Bilaterians). It consists of a sac-like structure containing a mineralised mass ( statolith) and numerous innervated sensory hairs ( setae). The statolith possesses inertia, causing the mass to move when accelerated. Deflection of setae by the statolith in response to gravityactivates neurons, providing feedback to the animal on change in orientation and allowing balance to be maintained. Because many echinodermsof this group have no “brain,” they are limited in their actions and responses to stimuli. The statocyst is therefore useful for telling the animal whether it is upside down or not. An upside-down echinoderm is in danger since its belly is not protected by its spiny skin.
otolith, an equivalent structure in vertebrates.
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statocyst — [stat′əsist΄] n. [< Gr statos, standing < histanai, to STAND + CYST] 1. Bot. a plant cell containing plastids, starch grains, or other statoliths 2. Zool. a sense organ found in many invertebrate animals, consisting typically of a fluid… … English World dictionary
statocyst — Cavity filled with fluid and particles acting as organ of orientation [Poore, 2004]. Diminutive organ providing sense of balance [McLaughlin, 1980]. Organ of balance at base of antennular peduncle in brachyurans [Ingle, 1992]. Sensory organ of… … Crustacea glossary
statocyst — noun Etymology: International Scientific Vocabulary Date: 1902 an organ of equilibrium occurring especially among invertebrate animals and consisting usually of a fluid filled vesicle lined with sensory hairs that detect the position of suspended … New Collegiate Dictionary
statocyst — n. [Gr. statos, fixed; kystis, bladder] An organ of balance found in many invertebrates, variable in structure from an open canal, vesicle, or closed chambers composed of one to many cells (lithocytes), that contains a concretion of granules of… … Dictionary of invertebrate zoology
statocyst — An organ for the perception of gravity and thus body orientation, found in many invertebrate animals; a cavity lined with sensory cells and containing a statolith … Dictionary of molecular biology
statocyst — /stat euh sist /, n. Zool. (in certain invertebrates) a sense organ consisting of a sac enclosing sensory hairs and particles of sand, lime, etc., that functions in maintaining equilibrium, serving to indicate position in space. [1900 05; stato… … Universalium
statocyst — noun A balance organ present in some aquatic invertebrates, consisting of a sac like structure containing a statolith and numerous innervated setae … Wiktionary
statocyst — n. organ which serves to maintain equilibrium in certain invertebrates (Zoology) … English contemporary dictionary
statocyst — noun Zoology an organ of balance and orientation in some aquatic invertebrates … English new terms dictionary
statocyst — stato·cyst … English syllables