Tuna Crab

Grimothea planipes is a bright red animal, up to 13 centimetres (5.1 in) long. It resembles a true lobster, but has a shorter abdomen.

Grimothea planipes lives on the continental shelf west of Mexico. It is usually found only south-west of San Diego, but in warmer years, its range may extend northwards into California. This is usually indicative of an El Niño event. Adults migrate vertically to near the ocean surface and large numbers occasionally wash up on beaches during warm water events. The southern limit of the species' range is in Chile.

Grimothea planipes usually feeds on protists and zooplankton, but will feed by filtering blooms of diatoms.

The life cycle of Grimothea planipes appeared for a long time to form a paradox: while an adult population was maintained along the south-western coast of the United States, the planktonic larvae they released were immediately swept by the California Current thousands of miles out to sea. A solution was proposed whereby the larvae use an opposing undercurrent at a lower depth to return to the continental shelf, and this hypothesis was confirmed by sampling different depths of water with a plankton recorder.