10 amazing facts about dock spiders

Dock spider

A dock spider emerging from its lair is a familiar lakeside sight—and it’s enough to make anyone want to dive directly into the water. But instead of getting squeamish about cottage country’s most famous arachnids, here are 10 reasons we should be celebrating them.

They’re Canada’s largest spiders

With nine species found in North America, they range in size, but can grow up to three inches across—about the width of your hand.

They don’t spin webs to catch their prey

Instead, they stalk their victims, using two large fangs to inject them with venom, paralyzing them. Don’t worry though, despite their fearsome size, their cuisine of choice doesn’t include human flesh.

However, they do spin webs to protect their young

Considered a “nursery web spider,” dock spiders reserve their silk for spinning egg sacs, which the momma spider carries in her fangs like a giant cotton ball. When they’re nearly ready to hatch, she spins another web, which shelters and protects her young.

An egg sac can hold up to 1000 baby spiders

As amazing as this fact is, we’ll understand if you get grossed out.

For one species, the dark fishing spider, death is an unavoidable part of mating

Male dark fishing spiders are only able to mate once. After discharging sperm into the female using an appendage called the pedipalp, the male remains stuck to his partner and dies within three hours. However, he usually won’t live that long—the female will eat her mate within 20 minutes, providing much-needed nutrients for healthy offspring.

Dock spiders are expert hunters

They catch and consume everything from insects to tadpoles to minnows—making them one of the few invertebrates that eat vertebrates.

This is why they are also commonly called fishing spiders

Dangling their front legs in the water allows the spiders to feel vibrations as their prey approaches. Sensitive leg hairs help them to differentiate between a leaf floating on the water and lunch—and to sense when a predator is approaching.

They have water resistant legs

Dock spiders’ legs are coated in a waxy substance. Combined with surface tension, this prevents them from being pulled down into the water.

And they can walk on water

Their unique legs allow them to complete amazing feats, including running across water and jumping vertically in the air to avoid being caught by fish.

They can “scuba dive” for up to half an hour

Using air trapped on their leg hairs and under their belly, they’re able to stay submerged underwater to hide from predators or to catch prey. So, before you dive off the dock to avoid them, remember that they might be in the water, too.

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