Creature of the Month
courtesy of Scuba News
Edible Sea Urchin
Echinus esculentus
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The spines of a sea urchin are mobile, being attached
to the test (or skeleton) with ball-and-socket joints. A sea urchin moves
using its tube feet, sometimes with the help of its spines. The urchin
also uses its spines to rigidly lock itself in a rock crevice. The shape
of the test varies depending on the depth of the water; those of
individuals living in shallow water tend to be more flat than those of
individuals living in deep water. The Latin name for the genus 'Echinus'
derives from the Greek for 'spiny'; the test bristles with many protective
reddish spines with lilac tips. Urchins are powerful and omnivorous
grazers, eating algae and animals like barnacles. They can leave virtually
bare swathes across a rock face. Rock-dwelling urchins such as Echinus
have a feeding mechanism known as Aristotle's lantern (it was he who first
described it), which consists of a complex structure of plates and muscles
that supports five chisel-like teeth used for scraping food from surfaces.
The species in our photograph, Echinus esculentus, is found from Finland
and Iceland in northern Europe down to Portugal in the South. Although its
common and scientific names suggest that Echinus esculentus is edible
(esculentus is the Latin for edible), only the reproductive organs (roe)
can be eaten. The Edible Sea Urchin lives for around 15 years, but some
urchin species are believed to live for more than for more than 200 years!
For a photograph of this sea urchin, see http://www.scubatravel.co.uk/forum/viewtopic.php?t=59
Further Reading: ---------------- Great
British Marine Animals, by Paul Naylor http://www.scubatravel.co.uk/britishmarine.html
