Undur-undur sea life by digging the sand at the seawater boundary at the beach,
a habit similar to that of raninid ketam, which also has a similar body shape, as a result of parallel evolution.
Unlike the galibnya ketam, the shape of the body of the sea retreat mostly almost oval, the first pair of legs (pereiopod) is not in the form of a sapit, and the tip of the tail (telson) is relatively large or long.
And unlike most of the decapods, sea retreats can not travel instead of, their legs adapt to be able to dig sand quickly.
Sea retreats can be found on sandy beaches in all parts of the world, with the exception of polar regions.
However, the larvae of one species are also found in Antarctic waters, although the region lacks the appropriate sandy beaches as a marine retreat habitat.
