Thyca crystallina

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Thyca crystallina
Thyca crystallina 002.jpg
Shell of T. crystallina
Scientific classification
T. crystallina
Binomial name
Thyca crystallina
(Gould, 1846) [1]
Synonyms [1]
  • Pileopsis crystallinaGould, 1846
  • Thyca (Bessomia) crystallina(Gould, 1846)
  • Thyca pellucidaKükenthal, 1897

Thyca crystallina is a species of sea snail, a marine gastropod mollusc in the family Eulimidae. It is one of nine species within the genus Thyca , all of which are parasitic on starfish in the Indo-Pacific Ocean. This species was first described in 1846 by the American conchologist Augustus Addison Gould as Pileopsis crystallina but was later transferred to Thyca . [1]



The shell of T. crystallina is conical, transparent and slightly curved, and is sculptured with longitudinal grooves. [2] The colour is variable and may be tan or bluish; the colouring does not necessarily resemble that of the host starfish. [3]


The species is located in the Indian Ocean and western Pacific Ocean, ranging from Madagascar to Hawaii. [3]


Linckia laevigata in the Tonga archipelago Linckia laevigata Tonga.jpg
Linckia laevigata in the Tonga archipelago

Thyca crystallina is an ectoparasite of a starfish, often the blue starfish Linckia laevigata or the multicolour Linckia multifora . [3] The mollusc larvae tend to settle on the upper side of one of the arms of the starfish, usually near its attachment to the disc. As they grow, they migrate to the underside of the arm, settling on the right side of the starfish's ambulacral groove, and orientating themselves towards its mouth, and here they become firmly attached. All the larger molluscs are female, and the larger of these have dwarf males attached to the starfish living under the front end of their mantles. [4]

This mollusc is at an early stage of becoming parasitic and has relatively few modifications to adopt this lifestyle. [5] The ventral surface has a central mouth and adheres to the starfish by suction created by the muscular pharynx. Nourishment is derived from grazing the host's tissues and the suction eventually forms a lesion. On larger individuals, a proboscis is inserted deeper into the host's tissues. [4] [5]

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Crown-of-thorns starfish Spiny coral-eating tropical starfish.

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Linckia genus of sea star

Linckia is a genus of sea stars found mainly in the Indo-Pacific region. They are known to be creatures with remarkable regenerative abilities, and capable of defensive autotomy against predators. They reproduce asexually.

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<i>Thyca</i> genus of molluscs

Thyca is a genus of small sea snails, marine gastropod mollusks in the family Eulimidae. These snails are ectoparasites of starfish; they are relatively unmodified, the underside having become a suction disc with a central mouth that draws nourishment from the host's tissues.

<i>Asterias forbesi</i> species of echinoderm

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<i>Eupentacta quinquesemita</i> species of echinoderm

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<i>Coscinasterias muricata</i> species of echinoderm

Coscinasterias muricata is a species of starfish in the family Asteriidae. It is a large 11-armed starfish and occurs in shallow waters in the temperate western Indo-Pacific region.

<i>Clistosaccus</i> species of crustacean

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  1. 1 2 3 Bouchet, Philippe (2010). "Thyca crystallina (Gould, 1846)". WoRMS. World Register of Marine Species . Retrieved 5 January 2018.
  2. G.W. Tryon (1886) Manual of Conchology v; VIII. Page 106
  3. 1 2 3 Gosliner, Terrence; Behrens, David W.; Williams, Gary C. (1996). Coral Reef Animals of the Indo-Pacific: Animal Life from Africa to Hawaii Exclusive of the Vertebrates. Sea Challengers. p. 141. ISBN   978-0-930118-21-1.
  4. 1 2 Elder, Hugh Y. (1979). "Studies on the host parasite relationship between the parasitic prosobranch Thyca crystallina and the asteroid starfish Linckia laevigata". Journal of Zoology. 187 (3): 369–391. doi:10.1111/j.1469-7998.1979.tb03375.x.
  5. 1 2 Combes, Claude (2005). The Art of Being a Parasite. University of Chicago Press. p. 25. ISBN   978-0-226-11438-5.