Black Urchin ( Arbacia lixula )

/ / Marine Inverts

Description

There are 10 species within the genus of Arbacia, with Arbacia lixula being the most widespread throughout the Mediterranean (1). None have been evaluated on the IUCN redlist (2). A.lixula is a regular urching, often up to 50mm in diameter, with a low and flattened profile It can be recognised by its thick, black spines, which are often about 30mm long and have a pinkish test (3).   It is usually found on rocky substrate from the water line, down to about 5 metres. However, it has also been found at 50m (4).

Habitat

It is usually found on rocky substrate from the water line, down to about 5 metres. However, it has also been found at 50m (4) Arbacia lixula is more commonly found on vertical substrate (6).

Life Cycle

Similar to other echinoids, A. lixula is gonochoristic and fertilisation is external.  They often become ripe during early spring, and is triggered by an external signal, such as a change in temperature or disturbance (5)

Distribution

A.lixula is one of the most common species in its genus. It is widespread throughout the Mediterranean although it is less common in the NW Mediterranean (3).

Food

It has been noted that A.lixula appear to prefer to feed on mainly encrusting corallines (6).

Conservation status

Not evaluated under the IUCN Redlist(2).

References

Description written by Kathryn Woodward (2009)

(1) Zipcode Zoo, 2007. Arbacia lixula. [Online] Available at: http://zipcodezoo.com/Animals/A/Arbacia_lixula/ [Accessed 16 June 2009].

(2) IUCN, 2009. IUCN. [Online] (2009.1) Available at: www.iucnredlist.org [Accessed 16 June 2009].

(3) Hayward, P., Nelson-Smith, T. & Shields, C., 1996. Sea shore of Britain and Europe. London: HarperCollinsPublishers Ltd.

(4) Wirtz, P. & Debelius, H., 2003. Mediterranean and Atlantic Invertebrate Guide. Germany: ConchBooks.

(5) Spirlet, C., Grosjean, P. & Jangoux, M., 1998. Reproductive cycle of the echinoid Paracentrotus lividus: analysis by means of the maturity index. Invert. Reprod. Develop, 1, pp.69-81.

(6) Bulleri, F., Benedetti-Cecchi, L. & Cinelli, F., 1999. Grazing by the sea urchins Arbacia lixula L. and Paracentrotus lividus Lam. in the Northwest Mediterranean. Journal of Experimental Marine Biology and Ecology, 241, pp.81-85.