Hairy-Handed Crab

Males and females are quite similar in appearance, both having a circular carapace that is slightly wider than it is long from the dorsal view. The New Zealand crabs are more green in coloration while the Chilean crabs are more brown. An array of pale spots can be seen on the carapace in a similar pattern for both sexes. Adult crabs have carapace widths of 2–4 cm (0.8–1.6 in) when they are fully grown. Small granules, or protrusions, can be seen on the shell from the ventral view towards the front of the crab. Eye sockets are wide. Few small teeth can be seen along the rim of the front sides of the carapace. Male appendages tend to be more pilose (hairy) at the base of the claws and along the lengths of the legs. The thickness of the hair sometimes even interferes with the operation and function of the claw.

H. crenulatus can be found throughout mainland New Zealand as well as the west coast of Chile. They are euryhaline, meaning they are able to survive in environments with a wide range of salinities. These may include estuaries, brackish waters, and the intertidal. In one incidence reported by E.F. Stead, between 1910 and 1912, after a storm had introduced a large influx of salt water to a freshwater lake, H. crenulatus populated the surroundings until the salt levels resolved. In the intertidal, there are rarely any below the low-water mark, although female crabs predominate at the lower levels.

They characterized as burrowing crabs, as they will hide under stones or burrow into sand and mud. Thus, they prefer softer substrates to help them avoid conditions of intense light, high temperatures, and high salinities.

The breeding season spans from June to January or February, with winter breeding being more common than summer breeding. The females are ovigerous, meaning they will carry the eggs on their undersides. Females are also capable of breeding twice within a season. Molting is generally concentrated before and after the breeding season. In perfect conditions of temperature and salinity, the minimum incubation time for the eggs was 45 days, with time and egg size tending to increase with lower salinity.