A pedicellaria (plural. pedicellariae) is a small wrench- or claw-shaped structure commonly found on Echinoderms, particularly in sea stars (class Asteroidea) and sea urchins (class Echinoidea). Pedicellariae are poorly understood but in some taxa, they are thought to keep the body surface clear of algae, encrusting organisms, and other debris in conjunction with the ciliated epidermis present in all echinoderms.
In sea stars
Pedicellariae in some taxa, such as the deep-sea Brisingida, and the Antarctic Labidiaster are known to function in food capture. Forcipulate sea star are so called because each pedicellaria is typically composed of three forceps-like valves. Other asteroids can have pedicellariae composed of only two components. In some asteroid sea stars pedicellariae are present around the base of a spine or on the surface of the animal's body. In other sea stars, they are present in pits on the abactinal, marginal, or actinal surface; often on the adambulacral plate adjacent to the tube foot furrow.
Four main forms of pedicellariae are found in sea urchins : tridactylous, ophicephalous, triphyllous and globiferous. The are generally attached by a long stalk in order to be at least as long as the secondary spines. In some families, globigerous pedicellariae have evolved into venimous structures, used for protection or maybe hunting. This is particularly the case in the family Toxopneustidae, some species such as Tripneustes gratilla and especially Toxopneustes pileolus being extremely venomous.
Tripneustes gratilla is also covered with venomous pedicellariae, but less dangerous.
- Ruppert, Edward E.; Fox, Richard, S.; Barnes, Robert D. (2004). Invertebrate Zoology, 7th edition. Cengage Learning. pp. 877–878. ISBN 81-315-0104-3.
- Christopher Mah. "What we know about the world's most venomous sea urchin Toxopneustes fits in this blog post !". Echinoblog..
|This echinoderm-related article is a stub. You can help Wikipedia by expanding it.|
|This animal anatomy–related article is a stub. You can help Wikipedia by expanding it.|