Cnidaria

The rare creature has only been spotted roughly 100 times since its discovery in 1899.

The photo, titled 'Medusa Ballet,' was recently announced as the overall winner at the European Wildlife Photographer of the Year 2021 competition.

NOAA researchers spotted a mysterious, blood-red jellyfish deep off the New England coast. It may be a new species unknown to science.

A beach walker in the U.K. recently stumbled across a dead compass jellyfish with a juvenile fish trapped inside its bell.

Biologists aren't entirely sure why thousands of jellyfish are swarming by Rhode Island.

Every few years, millions of by-the-wind sailor jellyfish wash up on beaches and die. What is causing so many of them to become stranded? The blob could be to blame.

The water surrounding upside-down jellyfish often stings to the touch, and now scientists know why.

Part ghost, part plastic bag, all amazing.

The barrel jellyfish is named for its massive size and silly-looking head, but it's rare for researchers to get up close and personal with one. Two divers in the U.K. recently had the chance.

Here's a jellyfish video with a twist … actually, make that 40 or 50 twists.