Beaches in Devon in the UK are being invaded by jellyfish in unprecedented numbers, and authorities warn that the invasion may force them to close down the beaches.

Big-sized barrel jellyfish were particularly seen along the shoreline during the past couple of weeks. Marine experts say there may be a bunch more to expect.

The last time that such a huge presence of jellyfish was noted was in the 1980s, but it was still significantly less than what has been witnessed this year, said Steve Trewhella, conservationist from Wareham, Dorset.

These sea creatures are piling up in the area mostly due to a combination of environmental factors. Almost everything jellyfish need—precise water temperature, abundant food supply and forces of wind currents—is present in these beaches. The number of jellyfish is continuously increasing, said Dr. Keith Hiscock, a marine life specialist and associate fellow of the Marine Biological Association of the UK.

Barrel jellyfish can grow in extreme sizes, by up to two to four feet in width, but experts say these are not the types of jellyfish that people should be concerned about, as people are rarely bothered by their sting. People should be more worried about the presence of the compass and blue jellyfish that have sting, experts say. Swimmers and beach aficionados are advised to stay away from these species.

Experts have also noted the continuous reduction of basking shark species in the Sound, and they credit this event to the invasion of the jellyfish as well. These large sharks do not prefer to swim with large jellyfish. An inadequate food supply and the scarcity of plankton may have caused the movement of the sharks. Although experts say the population changes among these species may be coincidental, they still take into consideration the simultaneous increase of jellyfish and decrease in basking sharks for years.

"I don't know what sort of authority the lifeguards have, but they would need to close the beaches across the whole region to all swimmers if any of the nasty ones came along," said Hiscock.

In Portugal, beaches have been closed down as the abrupt and outright invasion of jellyfish has been witnessed along the waters. This move may also be highly possible in the affected areas in the UK.

"It's the year of the jelly," Hiscock said. With the notable shifts in marine life populations, including that of basking sharks, "It's certainly been an interesting year."

Photo: Gene Selkov | Flickr