RECORD numbers of giant jellyfish are expected again this year after researchers reported a large increase in sightings across the south coast.

The barrel jellyfish, which are the biggest species of jellyfish found in the south west of England, are said to be thriving after a mild winter and rising levels of plankton, which they feed on.

See all the pictures of the giant barrel jellyfish that washed up on Dorset's beaches last year 

Several of the jellyfish, which can grow to the size of dustbin lids, were captured on camera by amateur photographer Andy Lyons at St. Aldhelm’s Head.

Mr Lyons, an assistant mechanic for Swanage RNLI, spotted them while out on a routine training exercise on Wednesday evening.

He said: “We started off at Chapman’s Pool for a man overboard exercise before moving on to St. Aldhelm’s Head. It was there somebody noticed them all around, about a mile from the headland.

“The light was going, unfortunately, but they were quite close to the surface and the sea was clear, so I was able to take a few pictures.

“I reckon there were about two dozen in total. When we went back to Chapman’s Pool, there were more there.

“I’ve never seen them before myself, but I know fishermen in Swanage have reported them coming up in their nets.

“Where the tide is so strong, and with easterly winds forecast, these jellyfish could end up anywhere,” he added.

Barrel jellyfish can grow up to 90cm (35in) wide and weigh as much as 25kg (55lb). Their tentacles can reach lengths of 6ft (1.9m).

Despite their size, their sting is very mild according to experts – although people are advised not to touch them.

Dr Peter Richardson from the Marine Conservation Society said:“Last year we had a record number of sightings of jellyfish and most were from the South West. It looks like it’s going to be a big year again for barrel jellyfish due to the mild winter. We’ve seen massive blooms since the end of March," he said.

“They are huge, the size of dustbin lids, and very rubbery and robust. When the weather warms up they rise to the surface to feed on the plankton and to breed.”

“They normally don’t occur in such numbers and they tend to bloom early, but last year we had reports of them right throughout the summer. I wouldn’t be surprised if we see massive numbers of them again this year with the warm weather," he added.