A new study recently published in the Journal of Biogeography reveals the driving force behind the evolution and distribution of the deep-sea dwelling king crab.
Researchers from the University of Southampton have compiled 200 years’ worth of oceanographic knowledge to discover that temperature is the main reason for the pattern of king crab distribution.
In deep waters across the globe, about 100 species of king crabs live mostly undiscovered. Only a small fraction have been found and it includes some very strange examples. The Paralomis seagrantii has its eight legs and claws covered in long, fur-like setae. The Lithodes megacanthus can grow up to 1.5 meters and has 15-20cm long defensive spines covering its body.
These crabs thrive in cold waters of around 1°C – 4°C. They live and grow very slowly and it is likely that they have very long life spans. King crabs are only found near the surface in the colder waters near the poles, though some parts of the Antarctic are too cold, even for the crab.
Sally Hall and Dr. Sven Thatje from the University of Southampton’s School of Ocean and Earth Science at the National Oceanography Centre discovered that soft-bodied forms can live at temperatures up to ten degrees higher than the hard-bodied forms, but both groups can only reproduce when the temperature is between 1°C – 15°C.
“It seems that most shallow-water representatives of this family are trapped in the coastal regions of the North Pacific because the higher sea surface temperatures further south prevent them from reproducing successfully and spreading,” said Dr. Thatje.
King crabs are of great commercial value and many fisheries have been established in high latitude regions of both hemispheres. Differences of only a couple of degrees will affect the distribution of the king crab, making the consequences of warming waters difficult to predict. “Understanding their evolutionary history and ecology is key to supporting sustainable fisheries of these creatures,” said research student Sally Hall. “Recent range extensions of king crabs into Antarctica, as well as that of the red king crab Paralithodes camtchaticus in the Barents Sea and along the coast off Norway emphasise the responsiveness of this group to rapid climate change.”
Copyright © 2009 Marine Science Today, a publication of OceanLines LLC