New Zealand Common Swimming Crab

Ovalipes catharus, commonly known as paddle crab, is a species of crab of the family Portunidae. It is found around the coasts of New Zealand, the Chatham Islands, and in south-eastern parts of Australia. Individuals from shallow waters, 0.1–0.5 metres (3.9 in–1 ft 7.7 in) deep, have a carapace width of only 10–15 millimetres (0.4–0.6 in), while those from 5–15 m (16–49 ft) are 100–140 mm (3.9–5.5 in) wide.