
This Is Why Water Striders Make Terrible Lifeguards
Season 4 Episode 15 | 3m 17sVideo has Closed Captions
They may look serene as they glide across the surface of a stream, but don't be fooled.
They may look serene as they glide across the surface of a stream, but don't be fooled by water striders. They're actually searching for prey for whom a babbling brook quickly becomes an inescapable death trap.
Problems with Closed Captions? Closed Captioning Feedback
Problems with Closed Captions? Closed Captioning Feedback

This Is Why Water Striders Make Terrible Lifeguards
Season 4 Episode 15 | 3m 17sVideo has Closed Captions
They may look serene as they glide across the surface of a stream, but don't be fooled by water striders. They're actually searching for prey for whom a babbling brook quickly becomes an inescapable death trap.
Problems with Closed Captions? Closed Captioning Feedback
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Learn Moreabout PBS online sponsorshipTo us, water striders are almost magical.
I mean, come on, they're literally walking on water.
But come down to their level and it's a bit more... sinister.
These delicate little bugs have figured out how to master the elements - and to exploit those who can't.
So how do water striders float where others sink?
The answer is those crazy long legs.
Water is pretty sticky stuff.
It likes to hold onto itself.
It sticks together especially well right at the surface.
If you're small, it can actually hold you up, as long as you don't break through that surface tension.
It seems like the water strider's legs would just sink right in.
But they don't.
They make dimples on the surface.
That's because their legs are covered in tiny hairs called micro-setae that repel water.
The strider's entire body is covered in them.
Those hairs trap a layer of air that keeps the water from sticking to its body.
The water strider simply can't get wet.
That's how they can sit on top of the water without breaking through.
Plus they're pretty light and they spread out their weight with their front and back legs.
They use their middle pair of legs to maneuver, by pressing down and back against those dimples.
Just like rowing a boat.
They can even catch some air.
Most of their fellow insects aren't quite as graceful.
Like this caddisfly.
Struggle as it may, it's stuck.. half-drowned...
Exactly what the water strider has been waiting for.
It probes for a weak spot And pierces through - spitting digestive enzymes in that dissolve its victim from the inside.
Then the striders take their time sucking out the innards.
Leaving the caddisfly a dried-out husk.
The stream delivers an endless buffet of new victims.
Because for most, that razor-thin line between water and air is a treacherous place.
But water striders know: keep your feet dry and you'll always have the upper hand.
Hey there, it's Lauren.
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