This beautiful pink urchin with unique spiny spines is seasonally
common on some of our Northern shores, in seagrass meadows. Sometimes
many are seen during a visit, and then none for a while. Broken spines
of this sea urchin may also be seen washed ashore.
Features: Body diameter 4-5cm.
It has spines on its spines! The thick spines are long (4-5cm), armed
with small spines and may be colourful and banded in pink and yellow
or beige. Because of its thick spines, it is sometimes called the
Pencil sea urchin. Several different kinds of spines may be seen even
on the same sea urchin. On the upper side, some long spines have sharp
tips and sharp small spines. Other long spines may be blunt or or
even square-tipped and have blunt small spines. On the upperside,
there are five short, sharp pointed spines usually held crossed over
one another forming a tent over the centre of the body. Long tube
feet may emerge from the sides of the spherical body when the sea
urchin is submerged in water. On the underside, the mouth is surrounded
by short flattened blunt spines. Other longer spines on the underside
have blunt tips too, possibly used for burrowing?
In some, the longer spines are covered sediments. Sometimes, tiny
brittle stars are seen wrapped around its spines. Or encrusting
ascidians may grow on the spines.
Pulau Sekudu, May 08
Upperside with five short sharp spines.
Mouth surrounded by flattened spines.
sea urchins on Singapore shores
Pulau Sekudu, Jan 06
With tiny brittle stars on its spines.
Pulau Sekudu, May 04
Chek Jawa, Oct 01
more photos of thorny sea urchins on Singapore shores
northern shores part 1 | part
2 | part 3 | part
Echinoid Directory by Dr. Andrew B. Smith on the London Natural
History Museum website: everything you could possibly want to
know about sand dollars and sea urchins with lots of large close-up
images and explanatory diagrams. Lots of technical descriptions
- Lane, David
J.W. and Didier Vandenspiegel. 2003. A Guide to Sea Stars and
Other Echinoderms of Singapore. Singapore Science Centre.