YOUR WEEKLY DOSE OF WOWZERS AND WONDER FROM THE NATURAL WORLD
This week’s featured friend is one of my favourites to relax and watch. But I’d never want to encounter one in person.
They’re majestic and one of the more unique creatures to float through Earth’s seas. Yet, underneath their beautiful bodies, they pack quite the punch!
We’re talking about jellyfish!
Jellyfish aren’t fish at all. Instead, they’re what marine biologists call gelatinous zooplankton.
Their bodies are made of up to 95% water. This means that jellyfish fossils are a bit rare. However, scientists estimate that they’re between 400 and 700 million years old.
That means they are older than dinosaurs!
There are an estimated 10,000 species of jellyfish swimming in Earth’s oceans today.
They range in size from the tiny Irukandji Jellyfish, which can be as small as 1 centimetre (0.39 inches) in diameter, to the massive Lion’s Mane jellyfish, which can have tentacles stretching 27 meters (88+ feet) long!
And jellyfish completely ignore the rules with their anatomy too!
They have no head, heart, lungs, or brain! However, a few jellyfish have eyes — such as the deadly Box jellyfish.
They can even clone themselves as polyps (baby jellyfish), creating additional jellyfish that are genetically identical.
Today, most scientists refer to a group of jellyfish as either a swarm or a bloom. A swarm is a gathering of jellyfish, while a bloom results from rapid reproduction.
We think the older name for a group of jellyfish — a smack — is a lot more fun, though!
Jellyfish eatsmall fish, crabs, shrimp, and aquatic plants by stinging them using cells in their tentacles called cnidocytes and nematocysts.
Then, they use their tentacles to bring their stunned or poisoned prey toward the opening on the underside of their bell — the dome-shaped upper part of their body.
Once inside, they digest their snack and expel the waste out of the same opening.
Some jellies are mostly harmless, causing mild discomfort when stung, while others can kill a human with just a single sting.
But while they sound like something you wouldn’t want to mess with, jellyfish have been a delicacy in some East Asian countries — including Japan and Korea — for centuries.
Animals find them tasty, too! Sea turtles, tuna, sunfish, and even some species of salmon chow down on jellyfish whenever they can.
Jellyfish aren’t endangered in any way. In fact, some of the ways we have changed the oceans seem to have made jellyfish even happier.
They love a floating pile of plastic to hide in, and warmer ocean temperatures appear to have sped up their reproductive rate!
While you’ll always want to view them from a respectful distance, this means there’s a good chance you’ll be able to find jellyfish at your local beaches or aquariums for generations to come.
Scientists estimate that the Box jellyfish has enough venom to kill 60 grown adults! Even if their sting isn’t deadly, the pain can last for weeks.
Jellyfish don’t breathe using lungs. Instead, they absorb oxygen directly through their outer skin-like layer.
One species of jellyfish — Turritopsis dohrnii — can age in reverse when threatened, returning to the polyp phase and cloning itself. This means they are possibly immortal!
Jellyfish come in various colours, from clear and dull browns to beautiful purples, pinks, and blues. Some jellyfish can even glow blue or green!
Break out your microscope and see how jellyfish sting in this interesting animated short by Neosha S Kashef and TED-Ed.