Can Spiders Swim? Can Spiders Float? Weird Diving Bell Spider (& Other) Facts

It’s summer at the lake and you’re ready for a refreshing swim, do you hesitate before jumping in to ask yourself, “Can spiders swim?”

Surely the water is the one safe haven from arachnids, right?

You may be surprised to learn that while spiders aren’t exactly fans of H₂O, many of these eight-legged critters can get around fairly well on the water.

While only one species – the diving bell spider – actually makes it home underwater full-time, others nest around lakes and streams, or even near backyard swimming pools.

This article explains the answer to the question, can spiders swim, by examining which types of spiders you might encounter in the water, which to beware of, and which leggy swimmers aren’t actually spiders at all.

Arachnids and Water: Can Spiders Swim?

There are at least 40,000 species of spiders out there in the Arachnid class, which also includes scorpions, ticks, and mites.¹

With so many different types of spiders on Earth, it’s no surprise that some have taken to the water in some way.

Do Spiders Like Water? Can Spiders Swim?

When it comes to water, a spider is no dolphin. They aren’t typically going to be seeking out water bodies to frolic in, but they do drink water to survive.²

They will seek water in many areas, from morning dew on the grass to drops of rain that have landed on their webs. Inside the home, many spiders make their homes around leaky pipes or other water sources for easy access to drinking water.

There are even a few species of spider that have evolved to be semi-aquatic, hanging out and stalking prey along the edges of ponds or lakes. One species, the diving bell spider, lives its entire life below the sea, but this species is a rare exception among arachnids.

Spiders in the Ocean: Can Spiders Walk on Water?

The light body weight of spiders combined with the high surface tension of water allows some species to float or walk on water.³

This generally is limited to very long-legged spiders that tend to live around water, such as fisher spiders or water striders (which are not true arachnids but are often referred to as spiders anyway).

The most interesting part of this phenomenon is that scientists who studied how spiders walk on water found that they can maintain this ability in almost any condition, whether the water is still or rough, fresh or salty.⁴

Theoretically, this means spiders in the ocean could manage just as well as spiders on a calm lake, but this is more difficult to study than spiders in a laboratory setting.

Spiders in Pool: Can Tarantulas Swim?

In 2018, arachnophobes found something new to fear when the Texas Fish and Wildlife Department posted a video on their Facebook page of a swimming tarantula.⁵ In the video, the tarantula can be seen using its legs to row itself quickly across the surface of a pond.

This doesn’t mean that tarantulas love the water, however. If they end up in this type of situation, they were almost certainly being chased or simply fell in.⁵

Even more reassuring, while they can row their arms on top of the water, they aren’t built to swim below the surface, so they would be easy to spot if you ended up in the pool with one. In addition, not all tarantula species can swim in this manner.

Some are too heavy, too large, or just the wrong shape to manage any kind of travel by water. In 2023, heavy rain in Australia washed spiders commonly found on land into some backyard pools.

(Image: Don DeBold¹⁷)

While most of these spiders were harmless, some homeowners reported finding deadly funnel-web spiders in the pool.⁶ These spiders can’t live in the water full-time but can trap air in their fur to survive in water for short periods.

When they ended up in pools, many would take refuge under the lip of the pool out of the water, posing a risk to swimmers and homeowners. Though common water spiders like fishing spiders or dock spiders are harmless, a funnel-web spider is a serious threat to life.

The good news is that they are only found along the eastern coast of Australia. Those living in this area should be cautious around these arachnids and be aware that they are one of the most aggressive spider species on the planet.

Dolomedes: The Water Spider

“Can spiders swim” is a common question, and of the 40,000 species of spiders that have been identified by scientists, only those within the Dolomedes class are closely associated with the water.

Fishing Spiders, Dock Spiders, and Other Water Dwelling Arachnids

Dolomedes, known as water spiders, are a class of semi-aquatic spiders that set up home around the water. These semi-aquatic species include fishing spiders, dock spiders, raft spiders, and wharf spiders.

All can run or float across the water with ease. They will often hunt by keeping six legs on land and using the other two to grab insect larvae and small fish from the water.

Most are dark brown with a characteristic yellow-to-white stripe, patterns of white dots on their abdomen, and white hairs on their substantial legs. These spiders can’t breathe underwater but can trap air bubbles in their hair that allow them to hang out in the water for short periods.⁷

Can Spiders Swim? Diving Bell Spider Swims With Ease

The only true swimming spider that lives full-time in the water is the Argyroneta Aquatica or diving bell spider.

It can swim underwater, float or walk on top of the water, and trap its air supply in an underwater nest or “bell.”

Sea Spiders and Water Striders

Some animals that live in a lake can look like spiders but aren’t part of the arachnid family. This includes water striders, which are six-legged insects that float or skim across the surface of the water, as well as creatures within the class Pycnogonida – or sea spiders, which includes roughly 1,500 different undersea species.⁸

Sea spiders look like land spiders but are a different class of creatures altogether. They range in size from so small you can’t see them without a microscope to more than 20 inches long.⁹

Sea spiders live everywhere from tide pools to the deepest parts of the ocean, and are particularly common in polar regions.

Diving Bell Spider: The Only True Underwater Spider

Only one single species, Argyroneta Aquatica – the only member of the Argyroneta genus – can truly live underwater full-time. This arachnid is better known by its common name, the diving bell spider.

Where Does the Diving Bell Spider Live?

Diving bell spiders live in freshwater all over Europe and Asia.¹⁰ They will settle anywhere freshwater can be found, including lakes, ponds, and streams.

What Does the Diving Bell Spider Look Like?

Despite being unique in their living situation, diving bell spiders aren’t all that distinguishable from other spiders. They range from around one-third of an inch to three-quarters of an inch long, are dark brown and velvety when out of the water, and can look silvery underwater because of the air bubble they are transporting.¹⁰

Unlike most spider species, the diving bell male tends to be larger than the female. This gives the female more space inside her bubble/bell to raise young because she takes up less space.

The male also has longer front legs than the female, which gives him an advantage when diving for his prey.

How Does the Diving Bell Spider Breathe?

The diving bell spider breathes oxygen, just like you do, but it has special talents that allow it to breathe underwater. This underwater spider uses its body hair to trap air from the surface and transport it underwater.

Because these spiders breathe from their abdomen, they can survive indefinitely thanks to this trapped air.¹⁰ Scientists describe it as a “physical gill.”¹¹

From here, the spider can fasten the bubble to plants, which serve as an anchor point for the nest. This bubble nest is called a bell and is what gives the spider its name.

Interestingly, these spiders can also use their silk spinnings to allow them to sail, catching the wind and floating across the water – a concept known as ballooning.¹²

Are Diving Bell Spiders Dangerous?

Diving bell spiders feast on prey found in the water, including crayfish, small fish, and insect larvae. They do have venom and the ability to deliver a painful bite to humans, but the bite is not fatal.¹³

You can avoid most bites from these spiders by using caution around potential hiding spots, including grasses and plants that grow in and around water. These spiders must also be anchored to something to bite, and can’t bite if they are free-floating or swimming.

When To Call an Exterminator for Spiders

If you don’t want spiders hanging around, your first step should be eliminating places where they like to hide. This means getting rid of clutter indoors and out and sealing cracks and holes in your home’s exterior that allow spiders to get inside.

If you find yourself plagued with black widows or brown recluse spiders, or you can’t seem to get rid of an infestation despite attempted efforts, it’s best to call an exterminator for help.

Different Types of Spiders in the U.S. That Can Harm Humans

There are two main types of spiders in the U.S. that pose a danger to humans. They include the Brown Recluse and the Black Widow.

While Hobo spiders, which have a distinct herringbone pattern and are found only in the Pacific Northwest, can also deliver a powerful bite to humans, they are not associated with the same public health risk as Black Widows or Brown Recluses.

How To Get Rid of Brown Recluse Spiders

The Brown Recluse is easily identifiable thanks to the brown violin-shaped mark on its back.¹⁵

This spider delivers a bite that can cause painful skin infections and serious health issues if not treated.

Fortunately, these spiders are also easy to get rid of, and the best way to do so is by eliminating the places where they like to live.¹⁵

1. Eliminate clutter inside and out.
2. Clean garages and sheds.
3. Replace cardboard boxes with plastic totes and other more secure storage systems.
4. Use caulk, expandable foam, and weatherstripping to seal any openings the spiders may use to enter the home.
5. Use sticky traps to ensure prevention methods are working.
6. Where spiders hide.

Pest Control for Black Widows

Known for the characteristic red hourglass on their abdomen, the Black Widow bite can make humans sick and is potentially fatal to children and the elderly.

Fortunately, pest control for black widows is relatively simple and is largely focused on getting rid of potential hiding spots and nesting areas.

1. Vacuum spiders, webs, and eggs if you see them.
2. Eliminate all outdoor debris.
3. Eliminate indoor clutter.
4. Keep woodpiles and vegetation away from the walls of the home.
5. Apply pesticides sparingly in cracks, voids, and overhangs where these spiders like to nest.

So while there are certainly spiders to beware of, rest assured that most are harmless.

While you now know the answer to “Can spiders swim?” you also know that if you run into one in the water, it likely poses little to no real threat to your safety.

Frequently Asked Questions About Can Spiders Swim