Fishing spiders big, not bad

Fishing spiders sometimes enter homes/Jim McCormac

COLUMBUS DISPATCH
NATURE

Fishing spiders big, not bad
Sunday April 29, 2012

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Cover your heads and mimic an ostrich, arachnophobes: There are about 600 species of spiders in Ohio. Spiders are probably the most numerous predators in most habitats. Sites that are rich in biodiversity might contain hundreds of thousands of spiders per acre. Fortunately for those who detest the eight-legged crowd, most spiders are so small and inconspicuous that people never notice them.

There are exceptions, however.

If there were a beauty pageant for spiders, the huge and sensational fishing spiders would be perennial front-runners for the tiara. Of course, beauty is in the eye of the beholder, but the leggy and intricately marked fishing spiders will always garner a reaction — pro or con.

Ohio hosts five species of fishing spiders, all members of the nursery web spider family. These arachnids don’t spin conventional webs; they ambush and pounce on prey. One might think of them as spider-cheetahs. Females with young are quite protective and spin a silken “nursery” chamber in which the juvenile spiders stay. The massive missus guarding the nest intimidates most would-be predators.

These are true titans. A female’s leg span can stretch to almost 4 inches. She would cover your driver’s license from end to end. As is usually the case in the spider world, males are far smaller — less than half the size of females in the case of fishing spiders. The size discrepancy makes mating risky business. Sometimes the suitor approaches a female with an offering of an insect, in hopes that the meal sates her appetite. If not, he might be the meal after their coupling is complete.

Fishing spiders are well-named: They’re almost always found near water. A water-repelling coat of hydrophobic hair allows the spiders to plunge into the drink if need be. They can even glide across the surface like a water strider, as their specially designed legs don’t break the water’s surface tension.
A fishing spider on the hunt lurks near the water’s edge, awaiting targets. The water’s surface, in effect, becomes its web. When the vibrations of a passing aquatic insect are felt via the spider’s sensitive palps (modified forelegs), the hunter explodes into action. Like a homicidal eight-eyed Mark Spitz, the spider effortlessly skates out and seizes the victim in its claw-tipped front legs. A bite from hollow fangs injects powerful venom, and the victim’s innards are soon sucked dry.

As horrifying as fishing spiders might appear, they are utterly harmless to people and are quite shy. The most nomadic of the group is the common fishing spider, which sometimes finds its way into homes. Seeing one of these behemoths on a wall might give you a jolt, but just prod it into a box or bag and let it go outside.
Spiders are pivotal in controlling all manner of insects that would otherwise surge out of control.


Naturalist Jim McCormac writes a column for The Dispatch on the first and third Sundays of the month. He also writes about nature at www.jimmccormac. blogspot.com.


Further afield
Colorful songbirds are migrating through central Ohio in droves. If you want to see grosbeaks, orioles, warblers and more, attend the “Birding at Its Best” program at Battelle Darby Creek Metro Park at 8 a.m. May 5. Meet at the Indian Ridge bulletin board at 2705 Darby Creek Dr., Galloway. For more information, call 614-508-8111 or visit www.metro parks.net.