Jellyfish: Helping to keep our ocean full of life

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.

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.

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.

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.

As you can see, jellyfish are an essential part of our delicate underwater ecosystem and provide a whole host of benefits to other marine life. You can read our report on jellyfish sightings from 2021-2022 here.