Many spiders can move through water, stay afloat, and even survive being submerged for a while. They use a mix of floating, paddling, trapping air, and special body features to handle water.
If you have ever seen a spider on a pond, in a pool, or on wet ground, you may have wondered why it does not sink right away. The answer involves physics and spider anatomy.
What Lets Spiders Move On Water
Spiders can move on water because the surface acts like a thin skin, and many spiders are light enough not to break it. Their legs have special coverings that help keep water from soaking in.
Surface Tension And Lightweight Bodies
Water has surface tension, which makes the surface behave like a stretched sheet. Small, light spiders spread their weight across that surface and avoid sinking.
Some spiders can run or skate across water because of this effect.
How Water-Repellent And Hydrophobic Hairs Help
Many spiders have water-repellent and hydrophobic hairs on their legs and bodies. These hairs push water away, so the spider stays drier and gets better grip on the surface.
A spider can paddle, skim, or stand on water without acting like a fish.
Why Walking, Skimming, And Paddling Are Not The Same
A spider that walks on water uses surface tension to stay up. A spider that skims moves quickly across the top, while a spider that paddles uses its legs to push through water.
Each movement helps the spider handle wet conditions in a different way.
How Spiders Survive Submersion
Spiders breathe air, so water is a challenge for them. Many can survive underwater for a short time by slowing down, sealing air in their bodies, or carrying a bubble of air with them.
Book Lungs, Tracheae, And Slow Breathing
Spiders breathe with book lungs and tracheae, not gills. Some spiders breathe very slowly and can hold their breath for a long time, which helps them survive if they fall into water.
How Air Bubbles Extend Time Underwater
Some spiders trap air in tiny hairs or around their bodies, which works like a scuba bubble. The diving bell spider, Argyroneta aquatica, carries an air supply underwater, and other aquatic spiders use similar ideas to stay alive in wet habitats.
Why Most Spiders Can Cope Briefly But Are Not Aquatic
Most spiders can handle a short dunk, but they are not true water animals. They can survive long enough to escape, rest, or wait for air after falling into a sink, bucket, or pool.
Which Spiders Handle Water Best
Some spiders are much better at handling water than others. The best water users often live near ponds, marshes, or flooded places, and a few species spend much of their lives in or around water.
Fishing Spiders And Dolomedes At The Water’s Edge
Fishing spiders in the genus Dolomedes hunt at the water’s edge. Species like Dolomedes fimbriatus and the raft spider can stand on water, chase prey, and dive to escape danger.
Their long legs and water-resistant hairs help them move across the surface with ease.
The Diving Bell Spider Argyroneta aquatica
The diving bell spider, Argyroneta aquatica, is one of the most unusual spiders in the world. It lives underwater most of the time and builds an air-filled silk web so it can breathe.
Wolf Spiders, Nursery Web Spiders, And Raft Spiders
Wolf spiders in the family Lycosidae sometimes end up in water and keep moving if they need to. Nursery web spiders and raft spiders also do well near water because they are active hunters and can use the surface to their advantage.
Trapdoor Spiders, Tarantulas, And Funnel-Web Exceptions
Trapdoor spiders do not swim. They survive flooding by sealing themselves in burrows and holding their breath.
Some people ask if tarantulas can swim. A few paddle for short distances, though they are not aquatic.
The northern tree funnel-web spider and other funnel-web relatives can survive brief water exposure. Water is not their natural home.
