World Jellyfish Day: Largest species of jellyfish in UK at Sea Life London Aquarium

Jellyogists at the London aquarium have bred the Barrel jellyfish from the infant stage as polyps in a special breeding laboratory.

Jack Willans, senior aquarist and lead jellyologist at Sea Life London Aquarium, said: “It’s pretty special to be the only aquarium in the UK to have reared Barrel jellyfish and put them on display.

“It’s the perfect way to celebrate World Jellyfish Day.

“It’s not been an easy feat to raise the Barrels as we’ve needed to ensure the water and feed remain consistent to allow them to grow, however I’m proud to say here at Sea Life London Aquarium we’ve managed to do just that.

“Barrel jellyfish can grow up to 50cms in diameter, so watch this space to see how big ours get.”

Jellyfish are one of the oldest multi-organ animals in existence, with scientists believing that they have been around for 500 million years. There are more than 350 different species of jellyfish.

The name Jellyfish is misleading as they are not classed as fish but as Cnidarians, like corals and sea anemones.

Their main body, called the bell, pulsates to drive them through the water trailing stinging tentacles behind them for catching prey. They have no brain or central nervous system but have nerve nets consisting of sensory neurons.

This produces signals in response to various stimulus such as the touch of prey. They rely on reflex reactions to their environment rather than conscious thought and decision making.

Sea Life London also has the most toxic jellyfish that swims in Mediterranean waters. The Pelagia Noctiluca jellyfish, or Mauve Stingers, are widely known for their excruciating sting and distinctive purple colouring.

Ruth Chamberlain, lead aquarist at Sea Life London Aquarium, said: “Mauve Stinger jellyfish are very toxic creatures - however they are also very captivating and can appear pink, purple, blue and even magenta in colour, and can even produce their own bioluminescent light in the dark.”

World Jellyfish Day is on Thursday 3 November.