Last updated on June 18, 2015
San Diego, California — In Southern California, beaches are covered with hundreds of thousands of tiny red tuna crabs.
The crustaceans are marring many US state beaches with vast streaks of red. It is believed that warm ocean currents are responsible for carrying them to shore.
Many of the tiny crabs have washed up on beaches from San Diego to Orange Country. While a large majority of them have died, some have been washed back out to sea alive.
Officials are saying that warm ocean currents are carrying the tiny red tuna crabs further north and closer to shore than normal.
Linsey Sala, collection manager for the Pelagic Invertebrates Collection at the University of California San Diego’s Scripps Institution of Oceanography, explains that these types of beach strandings do happen periodically and are not necessarily a threat to the species.
Sala does say, however, that “This is definitely a warm-water indicator. Whether it’s directly related to El Nino or other oceanographic conditions is not certain.”
Scientists have detected the presence of a toxic algae bloom in the Pacific Ocean that stretches from North California to the state of Washington. They say it may be the largest detection ever off the West US coast.
People are being cautioned to not eat the crabs because they may have ingested toxin-producing phytoplankton, warn Scripps experts. Although Sala was unable to say for certain if the beached crabs may be related to the algae bloom.
Sala explained that these particular crabs are unusual in that they can spend most, if not all, of their lives swimming rather than hovering on the ocean floor, although it is not uncommon for large adults to make trips to the seafloor.
The scientific name for the red tuna crabs is Pleuroncodes planipes and they also are known as pelagic red crabs. Sala says, “They are mostly grazers in the upper 200 meters (yards) of the ocean.”
The crabs are native to waters off the Gulf of California, Baja California and the California Current. They range between one and three inches in length and thrive on plankton.