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Can Spiders Swim? Aquatic Arachnids

can spiders swim, raft spider
Pmau, CC BY-SA 4.0, via Wikimedia Commons

Have you ever found yourself staring at a spider in your bath, wondering if it could survive being washed down the drain? You are just as curious as me if these eight-legged creatures are capable of swimming.

So, I did some research and discovered that the topic of spiders and water is more complex than I ever could have imagined. In this article, I’ll share what I learned about whether spiders can swim, including some surprising facts about which species are the best swimmers.

Can Spiders Swim?

Spiders can swim, but some are better at it than others. Water spiders are excellent swimmers and can catch their prey underwater. Raft spiders can float on the water’s surface using their legs.

The spider’s ability to swim primarily depends on its size, weight, and the density of its exoskeleton. Smaller spiders are more likely to be able to swim than larger spiders.

Next up, let’s find out whether these aquatic spiders can have one over on the legendary Michael Phelps.

Diving Bell Spider (Argyroneta aquatica)

The diving bell spider lives almost entirely underwater. To survive underwater, the diving bell spider creates a unique silk web that resembles a diving bell. This web serves as their air supply, allowing them to remain submerged for extended periods.

They spend most of their day positioned upside-down, waiting for their prey to swim past. When they see a mosquito larva or a small fish, they dart out and catch it. They then retreat back to their bell to feed.

They can breathe underwater by trapping air in between the hair on their body. They live in slow-moving water throughout Europe and Asia.

The image below shows two diving bell spiders, a female on the left and a male on the right.

Baupi, CC BY-SA 3.0, via Wikimedia Commons


Dolomedes is a genus of spiders made up of 101 recognised species. They are known as raft spiders, dock spiders, fishing spiders and wharf spiders. All of the spiders in this genus have a pale strip running down each side of their body.

They hunt on the water’s surface and prey on mayflies, insect larvae, and small fish. They use the very sensitive hairs on their legs and feet to feel vibrations given off by prey.

You can find them around the edge of ponds and ditches. Unlike the diving bell spider, which lives underwater, the raft spider spends most of its time on the water’s surface but can dive underneath to escape predators.

raft spider
LithobiusOrigins, CC BY-SA 4.0, via Wikimedia Commons


Can Spiders Swim Underwater?

Only the diving bell spider has adapted well to swimming beneath the water’s surface.

Can Tarantulas Swim?

Yes, tarantulas can swim. However, they are not good swimmers and only swim when they accidentally fall into the water. They use their long legs like oars to paddle across the water while the air pocket created between their hairs helps them stay afloat.

Can a Spider Drown?

Yes, spiders can drown if they are submerged in water for too long. Like all animals, they must surface to breathe air to survive if they do not have gills. If they stay underwater for too long, they will eventually succumb to drowning if they cannot find a way to escape the water.

Can a Spider Come Back up the Toilet if You Flush It?

Contrary to popular belief, spiders cannot return to the toilet if you flush them. Flushing a spider will send it through the pipes and out of your home. There are better ways to get rid of spiders in your house. Instead, try to capture them in an empty container so you can release them outdoors.

Can a Spider Survive Being Washed Down the Sink?

Spiders that are washed down the sink will likely drown if they cannot find a way to escape the water. Some may survive if they can cling to the sides of the drain or find a way to climb out of the sink.

Is It Cruel To Drown a Spider?

It is cruel to drown any animal, including a defenceless spider. It is always best to find a more humane way to deal with spiders if they are unwanted in your home. A large empty matchbox is the best way to catch a spider. Once you have caught the spider, release it outside.

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