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| zoanthids text index | photo index |
| Phylum Cnidaria > Class Anthozoa > Subclass Zoantharia/Hexacorallia > Order Zoanthidea |
| Sea
mat zoanthid Palythoa tuberculosa* Family Zoanthidae updated Aug 10
Where seen? Like some weird rubber mat that engulfs rocks and rubble, this colony of animals is often seen on many of our Southern shores. It is often found in areas where waves crash onto the rocks in shallow waters. When the animals find a happy spot, the colony can cover a large area. Features: Colony 20-40cm, each polyp about 1-2cm in diameter embedded in a common tissue. The polyp has a thick and short body column, topped by a wide oral disk edged with tentacles in two rows. When the polyps are expanded, their oral disks and tentacles may hide the common tissue. When the colony is out of water, the tentacles and oral disks are tucked into the body column, leaving on small puckered holes on the surface of the common tissue. Colours seen include brown, cream and yellow. The common tissue is thick and rubbery. It also feels rough to the touch because the tissue may be strengthened by incorporating fine sand and other tiny debris. One study suggests these incorporated elements can make up 45% of the total weight of the colony! Some sea mat species can grow rapidly, up to 0.4cm a day. They are quite aggressive and often overgrow other animals in the surrounding area. Some sea mat species have 'cracks' in the mat which are caused by clumps of polyps that are separating. Sometimes confused with sponges, ascidians and other blob-like animals. Here's more on how to tell apart blob-like animals. They are also sometimes confused with other zoanthids. Here's more on how to tell apart some zoanthids. Toxic mat: Sea mat zoanthids contain the highly toxic palytoxin. It is reported that the Hawaiian natives produced poisoned arrows by rubbing the tips on the zoanthid Palythoa toxica. It is believed that the toxins are not produced by the animal but by bacteria that live in symbiosis with the polyps. |
 Coating a rock in a rubbery mat. Kusu Island, Apr 05  Closer look at the polyps. Kusu Island, Apr 04  Sisters Island, Jul 06 |
Each is a colony of many little animals.
 St. John's Island, May 06 |
 Long tentacles when extended. |
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Sea mat zoanthids on Singapore Shores
 Pulau Hantu, Apr 06  A polyp splitting into two? |
 Pulau Hantu, Jul 03  |
 Pulau Hantu, Jun 10  Bleaching. |
more photos of sea mat zoanthids on Singapore shores
northern shores
southern shores part 1 | part 2 | part 3 | part 4 | part 5 | part 6
*Species are difficult to positively identify without close examination.
On this website, they are grouped by external features for convenience of display.
| Acknowlegement With grateful thanks to Dr James Reimer of JAMSTEC (Japan Agency for Marine-Earth Science and Technology) for identification of these zoanthids. References
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T.F. H Publications. 464 pp
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