What is a Cnidarian?
Let's start with the root word. Cnidaria is a phylum under Kingdom Animalia containing over 11,000 species of animals found exclusively in aquatic environments: they are predominantly marine. Their distinguishing feature is cnidocytes, which are specialized cells that they use mainly for capturing prey.
That's a lot of fancy science lingo!
Let me show you some organisms you've likely seen before!
Cnidarians can be broken down into four major classes.
Cubozoa (box jellies, sea wasp):
Anthozoa (sea anenomies, sea pens, and corals):
Hydrozoan (hydopoids and siphonophores):
Isn't it crazy to think that all of these diverse organisms can be related as Cnidarians?
Now that you've seen pictures of them, you can see the cnidocytes, which they all use for capturing their prey! You see, most organisms are grouped together by a defining trait or function, which they all have.
Next time you're on a dive trip and someone gets stung by a jelly, you can cleverly call it a Cnidarian or Scyphozoa and I bet it will greatly help the situation! Okay, maybe not. ;)