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Phylum Cnidaria > Class Anthozoa > Subclass Zoantharia/Hexacorallia > Order Actiniaria
Snaky anemone
Macrodactyla doreensis
Family Actiniidae
updated Jan 2020

Where seen? This large anemone has long snaky tentacles that resemble udon noodles. It is sometimes seen on some of our shores, on coral rubble and near seagrasses and reefs. Although generally only exposed at the lowest tides, it is said that the anemone is generally found no deeper than 5m.

Features: Diameter with tentacles extended said to reach up to 50cm but those seen usually smaller about 20-30cm. Tentacles snaky, thick and long (about 10cm). Sometimes (not always), the tentacles may be tightly coiled or curled especially when the anemone is submerged. It is also called the Corkscrew Tentacle anemone for this reason. To some (hungry) visitors, the anemone reminds them of a bowl of udon noodles!

The tentacles are close to one another at the circumference of the oral disk, and more sparsely distributed on the oral disk. Sometimes, a broad expanse in the centre of the oral disk around the mouth has no tentacles. There are white stripes radiating from the central mouth. The stripes may extend onto the tentacles. Tentacles and oral disk usually the same colour. Tentacles may be brown, green or purplish, but tips may be darker or lighter. The oral disk is purplish-gray to brown, sometimes with a greenish cast. The underside of the oral disk is purplish with white eye-shaped non-adhesive verrucae that extend onto the white body column.

Sometimes confused with other large sea anemones and similar large cnidarians. Here's more on how to tell apart large sea anemones with long tentacles and large 'hairy' cnidarians.

Snaky friends:
The 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. The zooxanthellae are believed to give tentacles their brown or greenish tinge.

Several kinds of animals have been associated with snaky anemones including anemone shrimps (Periclimenes sp.) and anemonefishes (Amphiprion sp.) including A. biaculeatus, A. clarkii (juvenile and adult), A. percula, A. perideraion, A. polymnus (juvenile and adult). But these are rarely observed on the Snaky anemones seen on the intertidal during low tide.

Human uses: Unfortunately, these beautiful animals are harvested from the wild for the live aquarium trade, although they are difficult to maintain in captivity.

Status and threats: This anemone is not listed among the threatened animals of Singapore. However, like other animals harvested for the live aquarium trade, most die before they can reach the retailers. Without professional care, most die soon after they are sold. Those that do survive are unlikely to breed successfully. Over-collection can also affect local populations.

Beting Bronok, Aug 05

White stripes radiating from the centre.

White eyed-shaped verrucae.

Cyrene Reef, Jun 12

With Peacock-tail anemone shrimp
(Periclimenes brevicarpalis)

Cyrene Reef, Mar 07

Tentacles in tight curls.

Beting Bronok, Aug 05

Body column purplish on the upper portion
and white on the lower.

Snaky anemones on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores


Changi Carpark 7, May 21
Photo shared by Toh Chay Hoon on facebook.


Pulau Sekudu, Jul 20
Photo shared by Jianlin Liu on facebook.

Chek Jawa, Dec 19
Photo shared by Loh Kok Sheng on facebook.

Beting Bronok, Jun 17
Photo shared by Loh Kok Sheng on facebook.

East Coast Park, May 09
Photo shared by Loh Kok Sheng on flickr.
Sentosa Serapong, Apr 2019
Photo shared by Abel Yeo on facebook.
Kusu Island, Jun 21
Photo shared by Richard Kuah on facebook.

Lazarus Island, Nov 17
Photo shared by Rene Ong on facebook.
Cyrene, Jun 20
Photo shared by Loh Kok Sheng on facebook.
Pulau Hantu, Apr 21
Photo shared by Jianlin Liu on facebook.

Pulau Semakau (South), Apr 2018
Photo shared by Jianlin Liu on facebook.

Terumbu Semakau, May 10
Photo shared by Loh Kok Sheng on his blog.

Terumbu Pempang Tengah, Nov 18
Photo shared by Juria Toramae on facebook.

Links
References
  • Daphne Gail Fautin, S. H. Tan and Ria Tan. Dec 2009. Sea anemones (Cnidaria: Actiniaria) of Singapore: abundant and well-known shallow-water species. The Raffles Bulletin of Zoology. Pp. 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 Hawai’ exclusive of the vertebrates Sea Challengers. 314pp.
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