Thousands of Red Crabs Invade Southern California Shores

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Aamna Mohdin

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613 Thousands of Red Crabs Invade Southern California Shores
Thousands of red tuna crabs on San Diego beaches. Scripps Institution of Oceanography

Beaches from San Diego to Orange County have been invaded by tiny red tuna crabs. Hundreds of thousands of these crabs have washed ashore due to warmer ocean temperatures, which are carrying them further north than usual.

“They are all still alive. They are in the surfline and swimming up,” Donna Kalez, manager of Dana Wharf Sportfishing, who spotted the unusual sight, told OC Register. “Once they get this close to shore, they can’t go anywhere, so they just wash in. They aren’t strong enough to swim out,”


While the vast majority of the red crabs have been dying, some have been washed back out to sea alive.

Scripps Institution of Oceanography

These red tuna crabs, Pleuroncodes planipes, usually inhabit the west coast of Baja California, Gulf of California, and the California Current. According to the Scripps Institution of Oceanography, though they are commonly referred to as red crabs, they are not ‘true crabs.’ This species usually live in the water column from larvae to adulthood, but some adult crabs have been known to live just above the seafloor and move to the surface to feed on phytoplankton. They’re typically around three inches (7.5 centimeters) in length.

"This is definitely a warm-water indicator," Linsey Sala, collection manager for the Pelagic Invertebrates Collection at the University of California, told Reuters. "Whether it's directly related to El Nino [sic] or other oceanographic conditions is not certain."


The first question on many people’s mind was can we eat them? There were reports that some people were taking the red tuna crabs home, but the Scripps Institution of Oceanography advises against it “due to unknown toxins that may be present within the crabs.” In particular, the scientists noted the biggest toxic algae bloom in the Pacific Ocean, which stretches from California north to Washington state, though they’re unsure how it might be related to red tuna crabs.

These red tuna crabs aren’t the only creatures that have been spotted along the coast this year; the OC Register has reported sightings of “blue, jellyfish-like creatures known as by-the-wind sailors” and “tropical fish like yellowtail and bluefin tuna.”


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