In other words, the statolith shifts as the animal moves. Any movement large enough to throw the organism off balance causes the statolith to brush against tiny bristles which in turn send a message to the brain to correct its balance.
Because many echinoderms of this group have only simple nervous systems without a controlling "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.
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^Ehlers, U. (1997). "Ultrastructure of the statocysts in the apodous sea cucumber Leptosynapta inhaerens (Holothuroidea, Echinodermata)". Acta Zoologica78: 61–68. doi:10.1111/j.1463-6395.1997.tb01127.x.
^Clarke, M. R. (2009). "The cephalopod statolithan—introduction to its form". Journal of the Marine Biological Association of the United Kingdom58 (3): 701–712. doi:10.1017/S0025315400041345.
^Cohen, M. J. (1960). "The response patterns of single receptors in the crustacean statocyst". Proceedings of the Royal Society B: Biological Sciences152 (946): 30–49. doi:10.1098/rspb.1960.0020.
^Israelsson, O. (2007). "Ultrastructural aspects of the 'statocyst' of Xenoturbella (Deuterostomia) cast doubt on its function as a georeceptor". Tissue and Cell39 (3): 171–177. doi:10.1016/j.tice.2007.03.002. PMID17434196.