Thalassina

Taxobox | name = "Thalassina anomala"
regnum = Animalia
phylum = Arthropoda
subphylum = Crustacea
classis = Malacostraca
ordo = Decapoda
infraordo = Thalassinidea
superfamilia = Thalassinoidea
superfamilia_authority = Latreille, 1831
familia = Thalassinidae
familia_authority = Latreille, 1831
genus = "Thalassina"
genus_authority = Latreille, 1806
species = "T. anomala"
binomial = "Thalassina anomala"
binomial_authority = (Herbst, 1804)
synonyms = "Cancer anomalous" Herbst, 1804
"Thalassina scorpionides" Latreille, 1806
"Thalassina scabra" Leach, 1814
"Thalassina emeryii" Bell, 1844
nowrap|"Thalassina talpa" White, 1847 ("nomen nudum")
"Thalassina gracilis" Dana, 1852
"Thalassina chilensis" Steenstrup & Lütken, 1862
"Thalassina maxima" Hess, 1865
"Thalassina squamifera" De Man, 1915

"Thalassina anomala" is a species of mud lobster found in the mangrove swamps of the Indian Ocean and western Pacific Ocean. Its nocturnal burrowing is important for the recycling of nutrients in the mangrove ecosystem, although it is sometimes considered a pest of fish and prawn farms.

Description

"T. anomala" is a lobster-like animal which grows up to 30 cm long cite book |title=A Guide to the Mangroves of Singapore |editor=Peter K. L. Ng & N. Sivasothi |chapter=Mud lobster, "Thalassina anomala" |author=Kelvin K. P. Lim, Dennis H. Murphy, T. Morgany, N. Sivasothi, Peter K. L. Ng, B. C. Soong, Hugh T. W. Tan, K. S. Tan & T. K. Tan |year=1999 |id=ISBN 9810413084 |publisher=Singapore Science Centre |chapterurl=http://mangrove.nus.edu.sg/guidebooks/text/2064.htm] , but is more typically 16–20 cm (6–8 in) long. Its colour ranges from pale to dark brown and brownish green [cite web |url=http://www.museum.wa.gov.au/dampier/explore_crustacean_mangrovelobster.asp |title=Mangrove lobster ("Thalassina squamifera") |publisher=Western Australian Museum |year=2006 |work=Marine Life of the Dampier Archipelago] . The carapace is tall and ovoid, extends over less than one third of the animal's length, and projects forward into a short rostrum cite book |url=http://ip30.eti.uva.nl/BIS/lobsters.php?menuentry=soorten&id=75 |title="Thalassina anomala" |work=Marine Lobsters of the World |author=Lipke Holthuis |year=1991 |publisher=Food and Agriculture Organization |pages=229–231 [ftp://ftp.fao.org/docrep/fao/009/t0411e/t0411e.zip download entire document] ] . The tail is long and thin, and, like many burrowing decapods, the uropods are reduced in form, and do not form a functional tail fan with the telson cite journal |quotes=no |title=The Thalassinoidea (Crustacea, Anomura) of Maharashtra |author=K. N. Sankolli |year=1970 |journal=Journal of the Bombay Natural History Society |volume=67 |issue=2 |pages=235–249 |url=http://decapoda.nhm.org/pdfs/22057/22057.pdf] . Various rows of setae on the legs and gills are used to prevent sediment from reaching the gills and for expelling any which does reach them. "T. anomala" also makes use of "respiratory reversal" to keep the gills free of dirt [cite journal |quotes=no |author=Zenon B. Batang & H. Suzuki |year=1999 |journal=Journal of Crustacean Biology |volume=19 |issue=4 |pages=671–683 |url=http://links.jstor.org/sici?sici=0278-0372%28199911%2919%3A4%3C671%3AGMOTML%3E2.0.CO%3B2-K |title=Gill-cleaning mechanisms of the mud lobster "Thalassina anomala" (Decapoda: Thalassinidea: Thalassinidae) |doi=10.2307/1549290] .

Distribution

"T. anomala" is found along the coast of the Asian mainland from Kerala, India to Vietnam, including Sri Lanka and the Andaman and Nicobar Islands. It is also found throughout most of the Malay Archipelago and the Ryukyu Islands, and its range extends south to most of Australia's north coast (from the North West Cape in Western Australia to Central Queensland), and east to Fiji and Samoa .

Ecology and behaviour

"T. anomala" lives in burrows up to 2 m (6 ft) deep, and is active at night cite web |url=http://www.naturia.per.sg/buloh/inverts/mudlobster.htm |title=Mud Lobster "Thalassina anomala" |author=Ria Tan |year=2001] . Its burrowing fulfils an important rôle in the mangrove ecosystem bringing organic matter up from deep sediments. The animal's output forms large volcano-like mounds which can reach heights of 3 m (10 ft) and are vital to many other species such as "Odontomachus malignus" (an ant), "Episesarma singaporense" (a crab), "Wolffogebia phuketensis" (another mud shrimp), "Idioctis littoralis" (a spider), "Acrochordus granulatus" (a snake), "Excoecaria agallocha" (a mangrove) and termites. The burrowing activity can cause "T. anomala" to be seen as a pest where it weakened the bunding that surrounds prawn farms or fish farms .

Use as food

In parts of its range, including Indonesia, New Guinea and Fiji, the claws of "T. anomala" are eaten, but the meat is bland and it is never very popular. In powdered form or steeped in alcohol, it is used in Thailand as a remedy for asthma .

Taxonomy

"Thalassina anomala" is the only widely recognised species in the genus "Thalassina", which is in turn the only genus in the family Thalassinidae (=Scorpionoidae Haworth, 1825) . There is considerable variation within the species , and it may be split into more than one species in the future . Thalassinidae is also the only family in the superfamily Thalassinoidea, although according to some classifications, it may be joined by other families such as Upogebiidae and Laomediidae cite journal |quotes=no |author=K. Sakai |journal=Crustaceana |title=The diphyletic nature of the Infraorder Thalassinidea (Decapoda, Pleocyemata) as derived from the morphology of the gastric mill |volume=77 |issue=9 |pages=1117–1129 |doi=10.1163/1568540042900268 |year=2004] .

Fossil record

Fossils of "T. anomala" are encountered "in countless numbers" [cite journal |quotes=no |journal=Transactions and Proceedings of the Royal Society of New Zealand |year=1950 |volume=78 |issue=2–3 |pages=269–270 |author=W. N. Benson & H. J. Finlay |title=A post-Tertiary micro-fauna in a concretion containing "Cancer novae-zealandiae" |url=http://rsnz.natlib.govt.nz/volume/rsnz_78/rsnz_78_02_003360.html] , and extend back as far as the Miocene. They are generally preserved in a hard phosphatic nodule which is believed to be the animal's moulting position. Storms may trap the animals in their burrows, and the mineral-rich nature of the sediments leads to very rapid fossilisation [cite web |url=http://webs.csu.edu/~epeters/Personal/Fossils.html |title=Too young to be an old fossil? |author=Eric Leif Peters |date=2005-08-04 |publisher=Chicago State University] . The presence of "T. anomala", together with other warm-water species in the Miocene of Japan (outside the current range of the species) is taken as confirmation of a period of increased temperatures 16 million years ago [cite journal |quotes=no |author=H. Karasawa & I. Nishikawa |year=1991 |title="Thalassina anomala" (Herbst, 1804) (Thalassinidea: Decapoda) from the Miocene Bihoku Group, southwest Japan |journal=Transactions and proceedings of the Palaeontological Society of Japan |volume=163 |pages=852–860 |url=http://ci.nii.ac.jp/naid/110002703322/en/] .

References