Portunus pelagicus
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 A mating pair of P. pelagicus
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| Portunus pelagicus Linnaeus, 1758 |
Portunus pelagicus, also known as the flower crab, blue swimming crab or sand crab, is a large crab found in the intertidal estuaries of the Indian and Pacific Oceans (Asian coasts) and the Middle-Eastern coast of the Mediterranean Sea. The name "flower crab" is used in east Asian countries while the latter names are used in Australia. The crabs are widely distributed in eastern Africa, south-east Asia, Japan, Australia and New Zealand.
The males are bright blue in colour with white spots and with characteristically long chelipeds, while the females have a duller green/brown, with a more rounded carapace. The carapace can be up to 20 cm in width.
They stay buried under sand or mud most of the time, particularly during the daytime and winter. They come out to feed during high tide on various organsims such as bivalves, fish and, to a lesser extent, macroalgae. They are excellent swimmers, largely due to a pair of flattened legs that resemble paddles. However, in contrast to another portunid crab (Scylla serrata), they cannont survive for long periods out of the water.
The species is commercially important throughout the Indo-Pacific. The species is highly prized as the meat is almost as sweet as the blue crab, and P. pelagicus is physically much larger.
These characteristics, along with their fast growth, ease of larviculture and high fecundity, makes this species ideal for aquaculture. Currently, P. pelagicus is aquacultured in Australia for the highly lucrative soft-shell crab industry[citation needed].
P. pelagicus is not striclty marine as it commonly enters estuaries for food and shelter. Furthermore, its life cycle is dependent on estuaries as the larvae and early juveniles use these habitats for growth and development. However, evidence has shown that early juveniles cannot tolerate low salinities for extended periods, which is likely due to its weak hyper-osmoregulatory abilities [1].
[edit] References
- ^ Romano, N. & C. Zeng (2006). The effects of salinity on the survival, growth and haemolymph osmolality of early juvenile blue swimmer crab, Portunus pelagicus. Aquaculture 260: 151–162.
