I'll ramble on about my love for cephalopods at the slightest provocation. They are, after all, the most-excellent of the invertebrates. Now I know there are some pretty fervent fans of beetles out there, and I'll admit their
diversity of forms and
downright beauty are impressive. And I personally know someone who studies the nudibranchs who would probably be aghast at my proclamation, and I can
certainly see where he's
coming from. But while both those groups are undeniably amazing in form, cephalopods are still the supreme creatures without backbones.
Why? Well, what it basically comes down to is that I don't worry about beetles or sea slugs taking over the world. For cephalopods I have no such peace of mind.
First of all, we'll never see them coming. Many of them have an incredible capacity to blend in to the environment. Some might call them "the chameleons of the sea," but frankly that's insulting because compared to cephalopods, chameleons are amateurs. Unlike what you might see in cartoons (
or faked YouTube videos), chameleons cannot perfectly mimic whatever color or pattern is near them. While some species can indeed change color and while it is useful for camouflage (mainly in the ranges of green and brown), they certainly can't replicate complex patterns and
the primary use of the ability is to convey emotional state. (Many of the videos you'll find online involve holding one up to a mirror so that it's fooled into thinking there's a rival in its presence, triggering the response.)
The good (or terrifying) news is that there actually are creatures who almost live up to that fictional prowess of chameleons, and which actually surpass it in some ways. Cephalopods such as cuttlefish and octopuses can indeed change their coloring to mimic their surroundings, and do a decent job of replicating complicated and artificial patterns:
As you can see, they go above-and-beyond chameleons both in the accuracy and subtlety of their colors and in the fact that they can actually change the shape and texture of their skin to blend in more completely.
Here's a short clip of an octopus blending in amazingly well before being spooked.
Some go even further, and imitate the shapes and behaviors of other living things: