Some of you may have heard of today's animal already, but I can't pass up the chance that even one of you might not have. It's just too cool.

The Diving Bell Spider is just like any other spider, except for the one little thing that makes it a complete freak -- it lives almost its entire life underwater. In a number of ways, this animal is closer to a fish than to other spiders. Other spiders might even think the Diving Bell Spider is a myth, like a mermaid. I mean, what would you think if someone told you that there was a race of humans who lived beneath the water, hunting and eating and mating and reproducing all underwater?

Because that's exactly what the Diving Bell Spider does. Both males and females create a tightly-woven bell-shaped piece of webbing that can hold pockets of air beneath them, and then anchor the bell with a single thread.

The spider then spends most of the rest of its life within the bell, under the water. Just like with other spiders, it will react as a predator when something touches the bell or the anchor thread, darting out of the bell and swimming through the water to attack with strong claws and venom. Though they are very small, their fangs can break human skin and cause inflammation. They hunt aquatic insects and small crustaceans, and food is taken back inside their air-filled chamber to be eaten.

The Diving Bell Spider can also capture relatively large bubbles of air around themselves, giving them a mobile supply that they can breathe while they swim about, like arachnid scuba divers. The entire bubble stays tightly around the spider, held by hairs on its abdomen and legs, a move it picked up after watching the air bubbles in underwater levels of Super Mario games.

But that's not all. The web bubble itself is not only completely waterproof, it actually acts as a membrane. When higher concentrations of carbon dioxide from the spider's breathing build up inside the web, it will diffuse through the web bubble and out into the water, while oxygen will diffuse from the water into the web bubble. The web bubble acts like gills for the spider, and in highly oxygenated water, such as in streams, the spider never even has to go up to the surface to gather more air bubbles for its bell. It can spend its entire life cycle beneath the surface, a feat not even matched by watergoing mammals such as whales. Even in low-oxygen water the spider only needs to replenish its oxygen supply at the surface once per day.

Unusually for spiders, the male Diving Bell Spider is larger than the female. This is because the male has a more active hunting style that requires it to swim around instead of waiting, and consequently it needs to be larger and stronger.

When mating season arrives, a male spider will build a new bell next to a female's bell. The male will then build an airlock between the two with his webs, and will chew through the female's web within the airlock, creating a passage between them. Once he has broken into her bell, they are able to mate. The eggs are laid and hatched within her bell.

Astonishingly adapted to spending its life underwater, the Diving Bell Spider lives primarily in Europe and northern Asia. Also known as the Water Spider, it is the only arachnid to have taken up this unusual aquatic lifestyle.