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Mud Lobster
Thalassina anomala

Mangrove Lobster/Large Mangrove Ghost Crab

mud lobster moundThese modest, shy creatures are responsible for the strange volcano-shaped mounds that are commonly seen in the back mangroves.

Mud lobsters are believed to eat tiny organic titbits in mud. To get enough nutrition, they have to process huge amounts of mud and sand. Processed mud is piled around their burrows as they eat-and-dig through the mud. Their mounds can reach 3m high.
Mangrove and wetland wildlife at
Sungei Buloh Nature Park
Main features: Lobster-like with a long "tail", held curved under the thorax.
mud lobster (seeking permission to use)
Photo from
Peter Ng and N Sivasothi
Small triangular rostrum. The clawed legs are unequal in size and the moveable finger (dactyl) is obviously larger than the fixed finger (pollex). Grows to 30-60cm.

Status in Singapore: Common.

World distribution: South Asia to Oceania. Indo-west pacific region

Classification: Family Thalassinidae. Mud Lobsters are not lobsters and related to ghost shrimps of the genus Callianasa.
Their burrows are U-shaped and can be up to 2m deep even below the waterline. During the day, mud lobsters plug up their entrance with mud. In the evening, these are opened and the mud lobsters may emerge. Mud lobsters prefer to dig in intertidal and subtidal regions.

Role in the habitat: Mud Lobster digging helps the mangrove community by recycling material from deep in the mud, loosening the mud and allowing air and oxygenated water to penetrate the otherwise oxygen-poor soil. This facilitates the growth of mangrove seedlings. Experiments show that seedlings of the Nipah Palm (Nypa fruiticans), Bruguiera and Ceriops grow more quickly on mud lobster-processed soil. Other plants found commonly growing on the mounds include Sea Holly (Acanthus spp.) and Blind Your Eye (Exoecaria algallocha).

'turrets' on moundThe mounds also result in pools which at low tide, provide shelter for small aquatic creatures. The mound is also a mini-habitat for a wide range of creatures, many of which have adapted to live only in a "Mud Lobster Condo". These include: an ant (Odontomachus malignus: its scientific name comes from its vicious sting!); a spider (Idioctis littoralis); the Mud Shrimp (Wolffogebia phuketensis: which lives permanently in a burrow in the mound, paddling a current of nutrients into its burrow at high tide).
kingfisher
mudskipperOther creatures that make use of condo facilities include mudskippers, water snakes (e.g., the File Snake, Acrochordus granulatus). The Collared Kingfisher (Halcyon chloris) sometimes nests in a large mound.

Status and threats: Mud lobsters are widely harvested throughout the tropical Pacific as food, and a variety of techniques have been developed for catching them. Fortunately, they are not a popular dish elsewhere. But they are considered a pest by prawn and fish farmers as their digging often undermines the bunds that form the foundation of prawn and fish ponds.

LINKS
REFERENCES
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Nature's Niche
  • Peter K L Ng and N Sivasothi, "A Guide to the Mangroves of Singapore II: Animal Diversity", Singapore Science Centre, 1999 (p. 86-87: description, habits, habitat, photos).
  • Michael Mastaller, "Mangroves: The Forgotten Forest Between Land and Sea", Tropical Press, 1997 (p. 66-67: habits, habitat, diagram).
  • Peter Widman (ed.), "A Guide to the Ecosystem of Palawan, Philippines", Times Edition, 1998 (p. 43: snippet on habit, photo).
 
By Ria Tan, 2001