A red bell jellyfish found near the surface of a clear sea. Its reflection against the surface can be seen also.

Jellyfish: Helping to keep our ocean full of life

1 minute read

Jellyfish are very important and beneficial to lots of marine creatures and help keep our seas full of life.

Before you continue!

Jellyfish are an essential part of many food chains but pollution, overfishing, and climate change are having a significant impact on them. By becoming a member you will be supporting our causes month on month, boosting the impact we have on bringing about massive change to our ocean.

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A barrel jellyfish | Image credit: Sam Morys

Jellyfish may seem like simple drifters, but they’re quietly doing essential work beneath the waves. These ancient creatures help support young fish, feed larger predators, and keep nutrients moving through the ocean. Far from being just summertime stingers, jellyfish are vital to keeping our seas full of life.

Protecting other species

While drifting through the water, jellyfish offer shelter and protection for some species of baby fish, enabling them to hide from predators. The tiny fish seek cover under the jellies, swimming with them as they move with the currents, which gives them a hiding place and the chance to journey through the sea unharmed.

Jellyfish also provide feeding opportunities for the young fish, who can snack on small organisms they find on the jellyfish, or any prey that the jellyfish zaps on its travels.

By providing sustenance and protection under their tentacles, jellyfish enable various fish species to grow in relative safety. This helps the fish, such as whiting in the North Sea and other commercially-important species, to increase their population and recover from depleting stock levels, which helps keep a richer variety of species swimming in our seas.

A compass jellyfish found in UK waters | Image credit: Mark Kirkland

Maintaining ocean food chains

Jellyfish are an essential part of many food chains. By feeding on smaller creatures such as fish larvae and eggs, jellyfish help to control species’ populations and maintain the balance of the ocean’s ecosystem. As well as eating other animals, jellyfish are often prey themselves – even for other jellyfish! Lion’s Mane jellyfish feed on the smaller Moon species, which are often spotted entangled in Lion’s Manes’ tentacles.

A yellow lion’s mane jellyfish passing through a moon jellyfish bloom

A yellow lion's mane jellyfish in the middle of a group of moon jellies

Image credit: Ron Watkins/Ocean Image Bank

Jellyfish are also an important part of the diets of sunfish, spadefish, crabs, and other large crustaceans, as well as marine turtles. Leatherback turtles’ diets consist almost entirely of jellyfish (their favourite is the Lion’s Mane), and they come to UK waters specifically to feed on jellyfish blooms in the summer - so jellyfish are especially important to the survival of these animals.

Even after life, jellyfish continue to sustain marine species, with deep-sea creatures like hagfish feasting on jellyfish remains soon after they fall to the bottom of the ocean.

Helping nutrients reach other species

Jellyfish help with nutrient cycling in the ocean – as they drift through different layers of the water column, they help to transport nutrients, such as nitrogen and phosphorous through the sea. These nutrients can then be recycled and used by other marine organisms for growth and survival.

Nutrients released by jellyfish through feeding or excretion are also a great source for other organisms, with a study finding that over 10% of nitrogen and almost a quarter of the phosphate requirements needed for the growth of phytoplankton were fulfilled through jellyfish excretion.

A stalked jellyfish | Image credit: Peter Bardsley

Help recording jellyfish as a bioindicator species

Jellyfish are an essential part of our delicate underwater ecosystem and provide a whole host of benefits to other marine life. Read our report on jellyfish sightings to discover the number and species of jellyfish that have been seen around our coasts each year.

We use scientific data, collected like this, to campaign for real change in the way we manage and protect our seas. If you see a jellyfish, dont forget to record it for us!