Huge Jellyfish Swarm San Diego Waters

Surrounded by water as they are, San Diegans are accustomed to all manner of aquatic wildlife, from miniscule sand crabs to monstrous gray whales. But this past week has local residents doing a double take as they gaze into the Pacific—large, dark purple jellyfish numbering in the hundreds have been sighted drifting around the San Diego harbor and washing ashore on beaches across the county over the course of the past few days.

Scientists say that the jellies are actually the rare Chrysaora achlyos, otherwise known as the black sea nettle. Over the last ten years, they have been turning up in coastal waters with ever increasing frequency—the large numbers seen in San Diego this week are almost unprecedented.

The reason for their heightened presence over the years may have something to do with warming ocean temperatures or a shift in the migration patterns of the nettles’ primary food source, plankton. But oceanographers are generally stumped as to why the creatures make periodic appearances in such massive numbers, and why, over the past eight decades, they have largely concentrated their arrivals along the coastlines of Los Angeles and San Diego.

In a statement to San Diego 6 News, Dr. Nigella Hillgarth of the Scripps Institute of Oceanography said Tuesday that the Birch Aquarium has captured four of the black sea nettles–which can grow to be up to three feet across with thirty foot tentacles–and placed them on display. “I think they’re beautiful,” she declared.

While there have been no reports of injuries or damage of any sort caused by the visiting jellies, Hillgarth warns that they can sting and that beachgoers and wildlife fans alike should remember to admire them from a distance.

Photos from jimg944 and amerune via flickr