Wild Profile: Meet the dock spider

An adult dock spider on a wood board By OliverGraphics.ca/Shutterstock

No cottage arachnid is more iconic than the dock spider. Canada’s largest eight-legged beast is about the same width as a CD (remember those?), and an expert bug hunter. Despite the name, these spiders mainly stick to the surface of lakes, ponds, and streams, preying on insects. They’ll also, however, dive for minnows and tadpoles.

A dock spider can run so easily and swiftly over water—75 cm per second—thanks to tiny hairs on its legs. This fuzzy covering helps to keep the legs afloat. Underwater, meanwhile, dock spiders can stay submerged for up to 45 minutes. This is a lot longer than a mink, muskrat, or even a Northern water snake, and, shockingly, about the same as a humpback whale.

Ten amazing facts about dock spiders.

Dock spiders are also called fishing spiders (for obvious reasons), and “nursery-web spiders.” Why? The arachnids don’t spin webs to catch prey, but the females do spin sturdy, round sacs, built to hold 500 to 1,000 eggs. A lady spider clutches this white sac beneath her, carrying it around like a tiny basketball, for about two weeks. Then, she spins a 20-cm-wide tent-like web, attached to vegetation or between some rocks, and hangs the egg sac inside. She waits, monitoring the eggs until they hatch into grey spiderlings.

Ma dock spider is a tough customer, and will bite if you were to, say, pick her up. (A bite feels a little like a bee sting.) But the maternal instincts that cause her to stand guard over her eggs also put her at a disadvantage; she’s exposed to bird and wasp predators. Yipes, practice some self-care, Mom!


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