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Grimothea planipes

Grimothea planipes
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Malacostraca
Order:	Decapoda
Suborder:	Pleocyemata
Infraorder:	Anomura
Family:	Munididae
Genus:	Grimothea
Species:	G. planipes
Binomial name
Grimothea planipes (Stimpson, 1860)
Synonyms
Pleuroncodes planipes Stimpson, 1860

Grimothea planipes, also known as the pelagic red crab, red crab, or tuna crab, is a speciesofsquat lobster from the eastern Pacific Ocean.

Grimothea planipes is a bright red animal, up to 13 centimetres (5.1 in) long.^[1] It resembles a true lobster, but has a shorter abdomen.^[2]

Grimothea planipes lives on the continental shelf west of Mexico.^[3] It is usually found only south-west of San Diego,^[1] but in warmer years, its range may extend northwards into California.^[3] This is usually indicative of an El Niño event.^[4] Adults migrate vertically to near the ocean surface and large numbers occasionally wash up on beaches during warm water events.^[3] The southern limit of the species' range is in Chile.^[5]

The life cycleofGrimothea 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.^[6]

Grimothea planipes usually feeds on protists and zooplankton, but will feed by filtering bloomsofdiatoms.^[7]

As the most abundant species of micronekton in the California Current, Grimothea planipes fills an important ecological niche converting primary production into energy that larger organisms can use.^[8] G. planipes is accordingly an important food item for many species of birds, marine mammals and fish. It is favoured by tuna, leading to one of the species' common names – "tuna crab".^[1] Other fish known to feed on G. planipes include billfishes, yellowtail amberjack, sharks^[9] and Epinephelus analogus.^[10] The diets of gray whales,^[11] Bryde's whales,^[12] blue whales^[12] and sea otters^[13] all include G. planipes. The Mexican endemic bat Myotis vivesi also feeds on G. planipes at some times of the year.^[14] Off Baja California, the stomachs of some loggerhead sea turtles have been observed to contain only G. planipes.^[15] Since G. planipes may be washed ashore in large numbers, it can be a valuable addition to the diets of seabirds such as the herring gull (Larus argentuatus), whose food supply is usually diminished in El Niño years.^[16]