New Zealand Common Swimming Crab

Ovalipes catharus

The New Zealand Common Swimming Crab, Ovalipes catharus, inhabits the shallow, sandy coastal waters around New Zealand and the Chatham Islands, with occasional sightings in southern Australia. This crab is identifiable by its oval, streamlined carapace, which is sandy grey with orange-red accents and small brown spots. Its rear legs are adapted as paddles, enhancing its swimming capabilities. Unique features include maroon eyespots and a butterfly-like mark on its carapace. This species is a nocturnal feeder with a varied diet, mainly consuming molluscs and crustaceans, and it exhibits cannibalistic behavior in some regions. During winter and spring, males carry females until they moult, after which mating occurs. Females likely move to deeper waters to care for and release their larvae. Divers may observe this crab swimming actively or quickly burrowing into the sand to evade threats. Although its population is thought to be on the rise, there are concerns about competition from the invasive Charybdis japonica. The crab is harmless to humans and has been commercially fished since the 1970s.