Even among the one million ocean species we know of and the nine million we don’t, jellyfish truly are the ancient aliens of the sea. They’ve been swimming Earth’s oceans for over 500 million years — and that’s just the beginning. Discover more wonderfully weird jellyfish facts below:
For starters, jellyfish aren’t actually fish, since they are invertebrates. For this reason, many people think they should be called “sea jellies” instead.
Because of its incredibly think skin, a jellyfish can get its oxygen from diffusion, and therefore doesn’t need a respiratory system.
Jellyfish are literally boneless, brainless, and heartless, and most are transparent.
Though they might not have brains, jellyfish do have a nervous system, or, nerve net, with receptors that can detect light, vibrations, and chemicals in the water.
Some jellyfish have ocelli, which are eye-like organs that are light-sensitive and can detect up and down motions. Ocelli appear as dark pigmented spots on the jellyfish.
The box jellyfish has more advanced vision: its 24 eyes give it a 360-degree view of its environment. It is also the world’s most dangerous jellyfish, and the most venomous marine creature. Certain species of box jellyfish can kill a person in just a couple of minutes.
Most jellyfish are found in warm, shallow coastal waters, but there are a few species that live in the cold depths of 30,000 feet.
Jellyfish can reproduce both sexually and asexually.
Green fluorescent proteins (GFPs) from the Aequorea victoria jellyfish species have transformed bio-medical research. The glow-in-the-dark proteins can illuminate specific proteins within the human body to track microscopic activity (for instance, cancer growth).
Jellyfish spawn at around the same time every day, usually dusk or dawn.