Creature of the Month

courtesy of Scuba News

Cup Coral, (Tubastraea aurea)
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The cup coral Tubastraea aurea is the pretty, orange,
tubular coral which you see growing beneath overhangs and
on the walls of caves.  It is at its most attractive at
night, when the coral skeleton is hidden by ring of bright
yellow tentacles. During the day the tentacles are
retracted into the coral tube.

The name comes from the Latin for tube (tubus) and the
Greek for star (astron). The skeletal tubes measure
5-15 mm across and protrude by 10 mm or more from the
coral surface. Tubastraea species occur from the surface
to depths of nearly 1500 m. There are four or five
species throughout shallow Indo-Pacific waters (Red Sea,
Thailand, Indonesia, Hawaii, etc.).

Until 1725 corals were classed as "stony plants".  Then
Frenchman Peyssonel discovered that corals were related
to anemones and realised that they were really animals.  
His findings, however, were not accepted at the time.

As Tubastraea grow in low light, they lack symbiotic
algae (which require light to photosynthesise).  This
in turn means that they grow relatively slowly and do
not contribute to reef building.

For pictures of Tubastraea aurea see
http://www.scubatravel.co.uk/hardcoral.html
http://www.scubatravel.co.uk/polyp.html