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Swimming
anemone
Boloceroides
mcmurrichi
Family Boloceroididae
updated
Nov 2019
if you
learn only 3 things about them ...
These animals are everywhere on the shore. Don't step
on them!
Don't pick them up. Their sticky tentacles will tear off
in your hands.
They
CAN swim but usually don't at low tide. |
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Where
seen? Looking like an untidy mop, this anemone
is sometimes seen in seagrass areas on many of our
shores. It is possibly
seasonal. Sometimes, large numbers are seen (up to 10-20 animals in
a trip) and then none at all. Once, we encountered an explosion of
countless tiny swimming anemones (less than 1cm across) in the seagrass
meadows of Chek Jawa.
Features: Diameter
with tentacles extended 5-8cm. The tentacles (3-4cm long) are thick
at the base, tapering to slender tips. There are LOTS of tentacles
(commonly more than 400). These hide the small oral disk and the mouth,
which is on a cone. Some have a white band on the oral disk across
the mouth. Sometimes, two of the tentacles near the mouth are prominently
lighter. The tentacles are generally shades of brown with bands in
darker brown or yellow. Sometimes those with spots, reddish tentacles
or white stripes along the tentacle length are see. It has a short
semi transparent body column and a small pedal disk which is not very
sticky. It's
scientific name is pronounced 'boll-loy-sir-roy-dee-des mac-moor-ree-eye'.
Sometimes mistaken for: Tiny swimming anemones may sometimes be confused with Seagrass
anemones which have translucent tentacles with tiny spots.
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Sometimes with white band next to
the mouth and two paler tentacles.
Pulau Sekudu, Jun 06
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Mouth is on a cone in the centre. |
Short body column and small pedal disk.
Changi, Apr 10 |
Does it really swim? Yes it can
swim slowly by undulating its many tentacles in a coordinated manner.
At low tide, these anemones are often seen loosely attached to seaweeds,
or just lying freely on the ground. They are rarely seen swimming
about. Possibly they are more active at high tide. Please don't pick up the anemone to force it to swim. Its sticky
tentacles will come off in your hand and you may hurt the anemone. |
Explosion of tiny swimming anemones.
Chek Jawa, Oct 10
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Many had settled on seagrasses.
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Adult (left) compared to tiny one (right).
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Losing it: The swimming anemone
can purposely drop of its tentacles if it is threatened. The dropped
tentacle can wriggle, probably to distract the predator. This dropped
tentacle can regenerate into a new swimming anemone after some time.
However, almost no other anemone does this. So please don't cut
an anemone into half hoping to get two anemones. You will instead
get no anemone.
What does it eat? The swimming anemone harbours
symbiotic single-celled algae (called zooxanthellae). The algae undergo
photosynthesis to produce food from sunlight. The food produced is
shared with the anemone, which in return provides the algae with
shelter and minerals. |
Reddish with spots.
Cyrene Reef, Aug 11
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Reddish with bands.
Cyrene Reef, May 12
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Brown with white stripes.
Cyrene Reef, May 12
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Swimming
sea anemones on Singapore shores |
Other sightings on Singapore shores |
Sembawang, Oct 20
Photo
shared by Vincent Choo on facebook. |
Coney Island, Oct 20
Photo
shared by Richard Kuah on facebook. |
Punggol, Jun 18
Photo
shared by Richard Kuah on facebook. |
Pulau Ubin, Dec 09
Photo
shared by James Koh on his
blog. |
Pulau Sekudu, Oct 11
Photo
shared by Loh Kok Sheng on flickr. |
East Coast Park, May 21
Photo
shared by Loh Kok Sheng on facebook. |
Sentosa, Sep 11
Photo
shared by Loh Kok Sheng on his
blog. |
Berlayar Creek, Oct 15
Photo
shared by Lisa Lim on facebook. |
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Pulau Tekukor, Nov 20
Photo shared by Jianlin Liu on facebook. |
St John's Island, Oct 20
Photo shared by James Koh on flickr. |
Lazarus, Jan 19
Photo shared by Marcus Ng on facebook. |
Sisters Island, Dec 10
Photo shared by Loh Kok Sheng on his
blog. |
Pulau Jong, Aug 20
Photo shared by Loh Kok Sheng on facebook. |
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Terumbu Raya, Jul 07
Photo
shared by Marcus Ng on his
blog. |
Terumbu Pempang
Laut, Apr 11
Photo shared by Loh Kok Sheng on his
blog. |
Pulau Pawai, Dec 09
Shared by James Koh on his
flickr. |
Links
References
- Daphne Gail
Fautin, S. H. Tan and Ria Tan. 30 Dec 2009. Sea anemones (Cnidaria:
Actiniaria) of Singapore: abundant and well-known shallow-water
species. Raffles Bulletin of Zoology Supplement No. 22: 121-143.
- Erhardt,
Harry and Daniel Knop. 2005. Corals:
Indo-Pacific Field Guide
IKAN-Unterwasserachiv, Frankfurt. 305 pp.
- Gosliner,
Terrence M., David W. Behrens and Gary C. Williams. 1996. Coral
Reef Animals of the Indo-Pacific: Animal life from Africa to Hawaii exclusive of the vertebrates.
Sea Challengers. 314pp.
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