Thousands of brightly colored, small red crabs have washed up on beaches near San Diego over the past few weeks.

The tiny red crabs — called tuna crabs or pelagic red crabs — usually live in the waters off the west coast of Baja California, the Gulf of California and the California current, according to the Scripps Institution of Oceanography, so it is unusual that they would venture as far north as San Diego.

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“Typically such strandings of these species in large numbers are due to warm water intrusions,” Linsey Sala, collection manager for the Pelagic Invertebrates Collection at Scripps, said in a statement.

Crab populations along some beaches are so thick that they resemble a "big red blanket," Orange County lifeguards chief Jason Young told the Orange County Register. Young also told the Register that he last saw these crabs in 1997, about the same time as the last substantial El Niño — a climate event that features above average ocean temperatures in the tropical Pacific Ocean, including near the Baja coast.

Sea surface temperatures are about 4 to 7 degrees milder than average, which could be driving the tiny crabs to the north, according to the Washington Post.

These kinds of crabs live their whole lives in the water column, rather than living part of their lives on land, like many other crabs do, Scripps said. Adult tuna crabs can live just above the sea floor and go up the water column, toward the surface to eat phytoplankton.

"Because they live in the water column, they are subject to the winds, tides, and currents," Scripps said.

If you do happen to run across one of these tuna crabs (or 1,000 of them) don't think that they're a free meal. Scripps warns that some of these little crustaceans contain toxins.