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posted: 10/4/2013 8:22 AM

Creepy creatures: Myths and truths about spiders, bats and snakes

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  • A brown bat is one of the types found in the Chicago suburbs.

      A brown bat is one of the types found in the Chicago suburbs.
    Daily Herald File Photo

  • Fox snakes may shake their tails like a rattlesnake, but they are not harmful to humans.

      Fox snakes may shake their tails like a rattlesnake, but they are not harmful to humans.
    Daily Herald File Photo

  • Many Halloween decorations are inspired by spiders and their webs.

      Many Halloween decorations are inspired by spiders and their webs.
    Daily Herald File Photo

  • Although some people fear bats, they are actually beneficial to humans by eating large quantities of insects.

      Although some people fear bats, they are actually beneficial to humans by eating large quantities of insects.
    Daily Herald File Photo

  • Two little brown bats hang out in the bat shelter at Lakewood Forest Preserve near Wauconda.

       Two little brown bats hang out in the bat shelter at Lakewood Forest Preserve near Wauconda.
    Paul Valade | Staff Photographer, 2003

  • Most spiders will not bite humans unless in self-defense, according to naturalist Valerie Blaine.

       Most spiders will not bite humans unless in self-defense, according to naturalist Valerie Blaine.
    John Starks | Staff Photographer

  • As one small spider methodically builds a nighttime web stretching almost three feet between tall weeds at the edge of the Almond Marsh in Grayslake, a second, identical spider tentatively approaches before being quickly dispatched to the weeds by the busy first spider.

       As one small spider methodically builds a nighttime web stretching almost three feet between tall weeds at the edge of the Almond Marsh in Grayslake, a second, identical spider tentatively approaches before being quickly dispatched to the weeds by the busy first spider.
    John Starks | Staff Photographer

 

A curious thing happens this time of year. Suddenly, animals that people fear are in great demand. Creepy life-forms are all the rage. Gross is good, repulsive becomes attractive, and despicable turns desirable.

The fleeting popularity of such creatures is fueled by Halloween caricatures, urban legends, and bad reputations that are hard to shake.

Spiders, snakes and bats top the list of these animals. Spiders are perhaps the top of the top.

Spider sense

Arachnids, the spiders and their kin are everywhere. One spider expert estimated that people are never more than 10 feet from a spider. Most people would freak if they knew that, but it's true: spiders are everywhere.

There's one under the sink, one behind the curtains, and one in the marigolds. There's one in the garage, one in the attic, and one in the grass. All of them are silently and unobtrusively doing their job. This job is twofold: eating invertebrate creatures and making more spiders.

Most stylized spiders in storefronts these days are anatomically incorrect. My favorite is the spider with 12 legs, one big, fat body, and sinister eyes -- with eyebrows, no less.

True spider anatomy is based on a simple body pattern: eight legs and a two-parted body. The majority of spiders have eight eyes (sans eyebrows).

An estimated 630 species of spiders call Illinois home, most of which go unnoticed by humans. If people do see a spider, their immediate reaction is to squash it. Why? Just because. If you press the question, you will probably get the answer that the spider is surely venomous and out to get them.

All spiders have venom, but not all venom is created equal. Venom has evolved in different species of spiders to be effective on their particular prey. Humans, it should be noted, are not on the menu. Many species of spiders don't even have the equipment to pierce human skin.

If a spider does happen to bite a human, it does so in self-defense. Spiders generally don't waste their expensive-to-make venom on non-prey items. Spider bites are often "dry bites" -- that is, with no venom.

What about black widows and brown recluses? Both species can be found here. The important thing is to not find them. In other words, don't make a habit of poking into dark crevices, burrowing in basements or crawling in woodpiles. These are the favorite spots for these species.

The north black widow would rather flee than fight an intruder. If it's cornered, it will inject a neurotoxin into its adversary, resulting in paralysis of the nervous system. The brown recluse can and will bite, but like the black widow, it would rather get the heck out of Dodge than have a showdown. If pressed, it will inject a cytotoxin, which leads to ulcers and tissue death.

Spider bites are the most falsely claimed medical emergencies, according to scientists at the University of Minnesota and the University of Iowa. The all-too-common misdiagnosis is made without ever seeing the alleged perpetrator of the crime.

Skin lesions of all kinds are blamed on spiders, when any number of other creatures could be the culprit. Compounding the problem of misdiagnosis is the fact that proper treatment requires identification of the species of spider.

There are arachnids that specialize in piercing skin, and these are perhaps the most disgusting of all eight-legged beasts: the ticks. Ticks differ from their arachnid cousins the spiders in anatomy and lifestyle. They have eight legs like spiders, but their head and abdomen are fused into one.

Their mouthparts are highly specialized for latching onto skin (human or otherwise) and sucking blood, their source of nutrition. They have evolved an amazingly effective strategy of lying in wait for their victims, called questing.

The tick assumes a position of readiness, with the third and fourth pair of legs clinging to a plant and the first pair of legs open, waving about to sense a passer-by. As soon as a mammal brushes the plant, the tick immediately grabs hold.

Ticks are notorious for transmitting diseases, such as Lyme disease. In our area, the small deer tick is the main culprit. There are several other species of ticks, such as the dog tick and the lone star tick, which is primarily found in southern Illinois.

During tick season, which lasts from early spring to late summer, be careful to stay on the trail and avoid walking through tall vegetation where the ticks lie in wait. If you do get a tick on you, pull it straight off. If it has been attached for a while and has begun to feed, see a doctor.

Arachnids are creepy, it's true, with all those hairy, crawly legs. There are creatures without any legs that are just as spine-chilling for many folks: snakes.

Suburban snakes

Halloween caricatures of snakes usually have mean-looking eyes with horizontal pupils, a long forked tongue (for stinging), and big rattles on the tail.

Venomous snakes do have horizontal pupils, and all snakes have forked tongues, which are merely sensory organs, not "stingers." Only rattlesnakes have rattles, but recent research suggests that some rattlesnakes are becoming rattle-less. (Presumably because those with rattles are most likely to meet the ax.)

There are some pretty darn dangerous snakes in the world. Fortunately, few live in northern Illinois. In fact, we're pretty lucky in the snake department, because the native species in Kane County are nonvenomous (an exception is the extremely rare massasauga, a species of rattlesnake that inhabits wetlands).

Like spiders, snakes are aloof and would rather not deal with people at all. They bite if provoked -- some more readily than others. Garter snakes, for example, can be feisty. They don't like to be picked up, and they'll let you know it if you try.

The northern water snake is downright irascible. Fox snakes often shake their tails in dry leaves, feigning a rattlesnake posture, but they're trying to say "Scram!" Brown snakes may fool you by their wormlike appearance, and milk snakes may startle you with their bold black and red pattern.

All in all, these native snakes in Kane County are beneficial predators and not at all dangerous to humans.

Beneficial bats

What would October be without bats? Likenesses of these flying mammals are everywhere this time of year -- construction paper-bats hanging from classroom ceilings, battery-operated bats with flashing red eyes, candy corn bats for trick-or-treats, and superhero bats sporting capes and masks.

Make-believe bats are a far cry from real-life bats. Legend has it that bats fly into human hair and sink their fangs into people's necks. In truth, Illinois bats are insectivorous and completely uninterested in human blood, let alone hair. Their biggest benefit to us is that they eat vast quantities of insects each night on their nocturnal rounds.

Fictional bats are ubiquitous, but bats in the wild may soon be a scarcity. A devastating disease known as white-nose syndrome has advanced through bat colonies across the eastern United States.

Named for the fungus' effect on bats' faces, the disease causes bats to wake up frequently during hibernation. This uses up the energy reserves needed to make it through the winter. Infected bats will often emerge from hibernation too early and starve or freeze to death.

An estimated 5.7 million bats have succumbed to the fungus since its discovery in 2006. Mammalogists are monitoring populations carefully as the disease advances into Illinois. Losing these insectivorous mammals will have a big ecological impact throughout the eastern United States.

Spiders, snakes, bats and other animals of ill-repute are everywhere this month. In real life, they're way cooler than their Halloween personas, and their presence is a plus in our lives. The autumn holiday will come and go, yet these silent creatures will continue to creep and crawl and slither and flutter all year long.

Chances are, we'll never see them, but it's an ecological treat just knowing that they're there.

• Valerie Blaine is a naturalist with the Forest Preserve District of Kane County. Email blainevalerie@kaneforest.com.

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