The Science Behind A Fishing Spider's Superpower

Have you ever wished that you could have a superpower? Maybe you want to fly, run like a flash or be invisible. Well, the fishing spider does have a superpower! This little critter can walk on water, but it’s not because of magic.

Fishing spiders can walk on water because of the science of surface tension. (Photo via Shutterstock)

Walking on water


Fishing spiders are able to walk on water because of something called surface tension. It’s science! Water molecules are attracted to each other. This bond is stronger at the surface, where water meets the air, which helps hold this crafty spider above the water’s surface.

Having a hard time picturing surface tension? Try this! Grab a penny and a cup of water. Using your fingertips, slowly drip water on the penny one drop at a time. The water will fill up the penny’s surface. The water is rounded and well above the penny. It should spill over, but like magic it doesn’t. Just like our spider friend, the round water bubble shows the science of surface tension.

Fishing spiders don’t walk on water for fun, though. They do it to escape predators and hunt. Contrary to popular belief, not all spiders spin webs to capture their prey. The fishing spider is one of the spiders that doesn’t make webs.

Fishin’ the day away


They’re called fishing spiders because, you guessed it, they fish for their food. These spiders have small spiky hairs on their legs that are very sensitive to vibrations on the water’s surface. They stand very still above the water, and when a small minnow or tadpole creates vibrations below the surface, the spider can sense the vibrations. If prey swims within striking distance, then the spider will dive, clasping its legs around its catch. That’s dinner!


Their diet isn’t only made up of fish. Fishing spiders spend a lot of their time on land hunting for insects with their sharp eyesight. The spiders hide in the underbrush until their prey is close, and then they pounce, encircling them with their long legs.


Walking on water isn’t the only unbelievable thing these spiders can do. They can also breathe under water! How? Small waterproof hairs near the spider’s abdomen create an air bubble. Their lungs are beneath their abdomens, drawing in oxygen trapped in the air bubble. This means they can stay under water for several minutes at a time — longer than we can hold our breath! This comes in handy when diving for prey or escaping from predators.


Human hunters?


Fishing spiders are pretty big spiders, with females reaching up to 3 inches long (including their legs) . That’s about the length of three quarters! Don’t worry, while these spiders are venomous, they are (mostly) harmless to humans. They are only aggressive toward us when they feel threatened. If you do happen to get bit by one, it will be annoying, but it will not hurt any worse than a bee sting.


Rest assured, the next time you go swimming in a lake or pond a fishing spider won’t mistake you for its next meal. But keep your eyes peeled because you might get a glimpse at these arachnid swimmers in action!

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