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Have you found a crab miles from the sea?

Have you found a crab miles from the sea?

Then you have found one of Hong Kong's true freshwater or amphibious crabs. Here a female with her eggs, found half way up the mountain at TaiMoShan.

There are a few different true freshwater species in Hong Kong, but today this is about the Hong Kong Freshwater Crab (Nanhaipotamon hongkongense) pictured above. Here she has the typical large, yolky eggs, held underneath the abdomen, where they are incubated, and the larval stages are suppressed (unlike marine crabs), so the hatchlings resemble a tiny adult.

Interestingly, there is no clear distinction between "terrestrial", "semi-terrestrial", and "aquatic" crabs, but even the most land-adapted crabs must still return to water to release their eggs.

The HongKong Freshwater crabs can be found many kilometres from the sea, and can lay their eggs in the freshwater streams that they live nearby (unlike others that have to complete annual migrations to the sea).

Here a little chappy found and photographed by Adam Francis, on Lady Clementis ride, halfway up the Peak!

Crabs belong to Crustacean, Order Decapoda which means 'ten legs': This refers to them having one pair of Chelae/claws and 4 pairs of legs that they walk on. The cheliped of male is usually larger than that of female. Legs bearing a chela are called chelipeds, so if you want to appear clever on your next walk, simply say "look out for his cheliped"!

Tomorrow we look at another more aquatic crab, the famous Mitten Crab. Don't miss it.


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