Did you know…jellyfish do not have blood, brains or bones…so technically, they aren’t even fish. They are some of the most interesting creatures in the world.
Due to their lack of bones, blood or brains, scientists have stopped calling them jellyfish – because technically they’re not a type of fish. Instead, they have called them sea jellies. They’re relatives of the phylum Cnidaria, which is the same family that corals and anemones belong to. So really, they’re like corals that can move through the sea!
If you’ve come across jellyfish while you’re diving or snorkelling, you’ll probably see these mysterious creatures as they slowly propel themselves through the ocean deep. They look like something out of a sci-fi movie.
Jellyfish are in every part of the world’s oceans. From warm tropical oceans to cold seas, jellyfish are everywhere. Scientists estimate that there are about 30,000 species of jellyfish that we don’t even know about yet.
They can produce both sexually and asexually, but there’s another jellyfish that can go through a process of life called ‘transdifferentiation’ – the Immortal Jellyfish, which has an insane ability to reverse its lifecycle!
The lion’s mane jellyfish is the largest jellyfish ever, which spans a whopping 2m, and its tentacles can trail up to 15m long. That’s half an Olympic-sized swimming pool.
What do jellyfish eat?
Jellyfish mostly eat smaller fish. They’ll often congregate together in a ‘bloom’ of other jellyfish, where they might feed on other fish in their larger numbers.
They eat:
- Fish
- Shrimp
- Crabs
- Small plants and crustaceans
How do they know which way to go?
Jellyfish have patterns in which they swim in directions – they’ll often swim a little bit away from the coast. They can sense temperature changes in the different oceans in which they swim, so they’ll often gravitate towards these different temperature zones.