Gulfweed Crab

Planes minutus is a small crab, reaching a maximum carapace length of 17.5 millimetres (0.7 in), and typically less than 10 mm (0.4 in). It has conspicuous eyes in wide orbits at the corners of the wide front edge of the carapace. The first pair of pereiopods (walking legs) bear a symmetrical pair of chelae with cutting teeth; the other four pairs are adorned with spines on the last two segments of each leg. It differs from the larger P. major in that males have a broadly triangular abdomen, rather than one which narrows abruptly after the third segment, and from P. marinus in having flattened legs with a fringe of setae that aid in swimming.

Planes minutus is found in the North Atlantic Ocean, between the latitudes of 11° N and 32° N, and also from the west coast of Africa, the Mediterranean and the Indian Ocean. Occasionally the crab has been recorded on the Cornish coast, the first publish record was at Falmouth in 1845 by William Pennington Cocks. Others specimens followed such as in 1848 (Falmouth) and 1899 on the Manacles. The latest occurred in 2015.

Related species, such as Planes major (formerly P. cyaneus) and Planes marinus, occur in other parts of the world's oceans

Planes minutus is exclusively pelagic, inhabiting a wide variety of substrates, including Sargassum weed, floating timbers and the hulls of ships. It is often found in association with turtles, especially the loggerhead sea turtle, Caretta caretta. It had been thought that the crab fed on the turtle's faeces, but it is now thought to fill a cleaning role. It is also found under the crevices of rocks from the lower intertidal zone of Dhamlej coast, Gujarat, India.