#3770 - Ovalipes catharus - New Zealand Common Swimming Crab
"spotless oval-foot". AKA Paddle Crab or pāpaka in te reo Māori.
Intact, they look like this. You might note the many spots, but they're much smaller and less obvious than they are in related crabs.
A Portunid crab found around New Zealand, the Chathams, and much less frequently around southern Australia. Opportunistic feeders and frequently cannibals.
In winter and spring the male carries the female until she moults, after which they can mate. They can produce sounds, although it's not at all clear how, which they may use to communicate with others of their species, to advertise food sources or identify mates.
A commercial fishery has existed since the 1970s, but is still recovering from the heights of the 1990s, and is now threatened by the invasive Asian Paddle Crab Charybdis japonica.
Moeraki Boulders, Otago, Aotearoa New Zealand.