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Male ‘Hoff crabs’, a species residing near hydrothermal vents in the Antarctic seafloor, have evolved larger claws than their female counterparts to battle for mates, a new study reveals.
The research, conducted by scientists from the universities of Portsmouth and Southampton, sheds light on the unique characteristics of this deep-sea crustacean, officially known as Kiwa tyleri.
The crab earned its nickname due to the dense hairs on its chest, reminiscent of the actor David Hasselhoff. These hairy chests aren’t just for show. They cultivate bacteria that the Hoff crab feeds on, allowing it to thrive in the harsh environment around hot vents.
The study, which examined 135 Hoff crabs at the East Scotia Ridge in the Scotia Sea, focused on the significant difference in claw size between males and females. This dimorphism, researchers believe, is driven by male competition for mating opportunities.
The Hoff crab belongs to the Kiwaidae family, often called “yeti crabs” because of their bristly appearance. This latest research provides further insight into the unique adaptations of these deep-sea dwellers.
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.”
Source: independent.co.uk
