Male crabs of a species named after David Hasselhoff grow bigger claws than females so they can fight each other for a mate, according to a new study.
Scientists from the universities of Portsmouth and Southampton discovered the difference in claw size while monitoring the “Hoff crab”, which gained its nickname thanks to its hairy chest, prompting comparisons with the Baywatch star.
The species, which has the official name of Kiwa tyleri, lives in large communities around hot vents on the seafloor in Antarctica and its many hairs host bacteria which the crab feeds on.
The latest study examined 135 of the crabs – which are part of the Kiwaidae family which are also known as “yeti crabs” because of their bristly appearance – at the East Scotia Ridge in the Scotia Sea.
Dr Nicolai Roterman, a deep-sea ecologist from the University of Portsmouth and lead author of the study published in the journal PLOS One, said: “This is the first study to show claw sexual dimorphism in yeti crabs which live exclusively in harsh deep-sea environments like hydrothermal vents and methane seeps.
“Knowing that there’s a difference in size between the male and female claws helps us understand the behaviour and ecology of the yeti crab family – which we know little about because they are a fairly recent discovery, and their home is very difficult to reach.
“Physical differences between males and females is a common feature of decapod crustaceans which live in shallow water, and usually it’s because the male is forced to guard the mate, or females have to divert their growth energy for reproduction.”
The team compared the Hoff crab with another yeti crab, the Kiwa puravida found off Costa Rica, which does not show difference claw sizes between the sexes.
Dr Roterman said: “This could be because the Costa Rica yeti crabs may be using their claws – which are longer and hairier than those of the Hoff crab – primarily for food production rather than fighting, or perhaps there is some other factor at play that we have yet to discover.
“We don’t yet know if these claw sex differences are the norm for the yeti crab family, or an exception. But the discovery provides a starting point for future research.”
Dr Roterman, who coined the Hoff nickname when the species was first discovered in 2010, added: “Understanding the physiology, behaviour, ecology and evolution of animals adapted to the most extreme conditions give us insights into what evolution is capable of, and therefore how life is likely to adapt to a warming planet and other natural and human-induced ecological stressors.”
