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 gravity activates neurons, providing feedback to the animal on change in orientation and allowing balance to be maintained. Because many echinoderms of 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.

ee also

*Inertial guidance
*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

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