Claw Strength of Lithodid King Crabs in Antarctic Waters

King crabs (Lithodidae) and other durophagous (shell-crushing) predators have been absent from shallow waters around Antarctica for as long as tens of millions of years. Now, however, deep-sea populations of lithodids off the western Antarctic Peninsula (WAP) may be expanding their bathymetric ranges. Their emergence on the Antarctic shelf could restructure the endemic seafloor communities, which are dominated by slow-moving, lightly structured invertebrates. On the other hand, calcification rates are low in polar waters, so the chelae of Antarctic lithodids are likely to be weakly constructed compared with crab chelae in temperate and tropical waters. We examined the strength of chelae in specimens of the lithodid Paralomis birsteini, collected from the continental slope off the WAP in 2015. We describe the strength of the chelae and their potential to generate force compared with the force required to crush their prey. We also compare the gape-width of the chelae with the size of potential prey items on the continental shelf off the WAP. Lithodids off the WAP are able to generate more than enough force to crush the tests or shells of the endemic invertebrates on the continental shelf off Antarctica. Our findings suggest the emergence of lithodids on the continental shelf off the WAP would have a drastic impact on resident populations of endemic vertebrates.