Let’s face it—most humans regard snakes and spiders as extremely unsettling. One is responsible for 81,000 to 140,000 deaths globally, while the other, though rarely deadly, is often just as venomous.
These two animals have evolved to become some of the most feared terrestrial creatures on the planet, thriving in environments where many others would falter. While we typically associate snakes with jungles or deserts and spiders with dark corners or forests, some species have adapted to remarkably unusual habitats.
Take, for example, the boa constrictor, which is commonly thought of as a jungle-dweller. However, one of the strangest places it’s been found is on the Caribbean island of Aruba, where it inhabits arid, cactus-filled landscapes.
On the other hand, the desert tarantula is a spider you’d expect to find in a hot, arid desert. But, amazingly, some tarantula species, like the Goliath birdeater of South America (known for being the heaviest of all spider species), have been spotted thriving in damp, swampy areas, far from the dry conditions most people associate with tarantulas.
While these unusual habitat adaptations are impressive, what’s mind-blowing is that certain species of both snakes and spiders have not only ventured into the water but also spend pretty much their whole lives under its surface. The adaptations these two species have developed would seem alien even to their closest cousins. Here they are.
1. The Diving Bell Spider, Which Weaves Itself A ‘Temporary Gill’ Underwater
The diving bell spider (Argyroneta aquatica) sounds like a fictional creature that shouldn’t exist in the real world. Most spiders spin their webs in trees, corners or other dry environments, but the diving bell has adapted to a completely watery lifestyle, with a diet that includes aquatic insects and small fish. Found in freshwater habitats across Europe and northern Asia, this spider spends almost its entire life submerged underwater, a feat that seems impossible for an air-breathing arachnid.
Typically small and light—measuring about 0.3-0.6 inches and weighing in at only a few milligrams—this little guy has evolved to create a unique underwater web, known as a “diving bell,” which it anchors to submerged vegetation.
The spider is capable of carrying air bubbles from the surface down to its web thanks to the fine hairs that cover its body. This creates a portable air pocket that allows the spider to breathe and move about freely while submerged. The structure of this bell is also “oxygen conductive,” meaning it absorbs dissolved oxygen in the water and supplies it to the spider—essentially acting as a gill. Moreover, its metabolic rate has adapted in such a way that it requires less oxygen that your average arachnid.
These evolutionary traits have allowed the diving bell spider to carve out a niche in an environment that would otherwise be inhospitable to its kind, surfacing just about once a day, according to a July 2011 study published in the Journal of Experimental Biology.
2. The Yellow-Bellied Sea Snake, Which Can ‘Breathe’ Through Its Skin
The yellow-bellied sea snake (Hydrophis platurus) is an extraordinary reptile that spends its entire life in the ocean, far from any land. Found in the warm tropical waters of the Indian and Pacific Oceans, this snake is a highly venomous marine predator, easily recognized by its vibrant yellow underbelly and sleek, paddle-shaped tail designed for swimming.
While the yellow-bellied sea snake has a pair of lungs like all snakes, it has also developed a fascinating adaptation that allows it to remain submerged for extended periods. Its skin is capable of absorbing oxygen directly from the surrounding water—a process that’s sometimes described as “breathing” through its skin. This unique adaptation supplements the oxygen the snake takes in through its lungs, enabling it to stay underwater for hours at a time while it hunts.
This particular sea snake’s skin is much thinner than that of other snakes. This allows it to respire through its skin—absorbing oxygen from the water—while also minimizing water loss. This is important because, according to a May 2014 study published in Proceedings of the Royal Society B, the poor snake is dehydrated for the better part of the year.
Its scales are uniquely shaped and arranged with deep grooves that trap water, keeping its skin moist even when it’s partially out of the water. This moisture is vital, especially when the snake floats on the ocean’s surface, searching for prey.
Plus, the snake sheds its skin frequently, which helps keep it clean and free of debris in the salty sea. These adaptations make the yellow-bellied sea snake perfectly equipped to thrive in its oceanic home, according to an April 2019 paper published in the Journal of Morphology.
Ultimately, though these snakes and spiders have evolved different strategies for surviving their underwater life, their adaptations are equally clever. Whether it’s a spider weaving its underwater home/gill or a snake that breathes through its skin, nature’s ingenuity is always full of surprises.
Does the thought of encountering a snake or spider the next time you’re swimming give you chills? Take this test to find out how brave you are when it comes to animals: Fear Of Animals Scale
