Southern California's coastlines are being invaded by millions of tiny red crabs, as warmer ocean currents carry them closer to shore than usual.
Red tuna crabs have been washing up and dying in droves on beaches fromSan Diego to Orange County, although some are making it backout to sea alive.
Experts say this sort of thing can happen every so often, and it is not necessarily a threat to the species.
Linsey Sala, of the University of California, San Diego's Scripps Institution ofOceanography, said: "This is definitely a warm-water indicator."
"Whether it's directly related to El Nino or other oceanographic conditions is not certain."
Scripps has cautioned people not to eat the crabs because the creatures may have ingested toxin-producing phytoplankton.
Currently, there is a toxic algae bloom in the Pacific Ocean stretching from California north to Washington state that might be the largest ever detected off the West Coast. Sala could not say if the crab influx could be related.
The crabs are unusual in that they can spend most if not all of their lives free swimming in the water column rather than close to the bottom, although larger adults will make excursions to the seafloor, Sala said.
The plankton-eating crabs, native to the waters of the Gulf of California, Baja California and the California Current, are one to three inches long and resemble tiny lobsters.
"They are mostly grazers in the upper 200 meters of the ocean," Sala said. "Because they can swim in the water column, they can be transported by strong currents."