Gentle Giants

They’re big. They’re hairy. But are they really scary?

As the sun sinks over an Ozark glade, birds quit singing, collared lizards bustle off to bed, and the night shift for this dry, rocky habitat shows up for work. Mice scurry about, gathering seeds in the safety of darkness. An owl hoots nearby, reminding the rodents that night doesn’t hide them nearly as well as they hope. And, from an almost invisible hole at the base of a lichen-covered rock, a furry, eight-legged predator creeps out into the gloom.

The Texas brown tarantula is Missouri’s largest — and some might say, spookiest — spider. From the tip of its fangs to the end of its abdomen, a tarantula’s body can stretch over 2 inches long. Girls grow slightly larger than boys and can weigh more than some songbirds. Add in eight furry legs, and you end up with a spider that’s nearly as big as a tea saucer. It’s no wonder why some folks are scared of them.

But though they look ferocious, tarantulas are surprisingly shy and go to great lengths to avoid people and predators.

Home Sweet Hole

Tarantulas are homebodies, spending the bulk of their lives hiding in a hole. Sometimes a spider will dig its own burrow, using its fangs and pedipalps to excavate loose soil. (See Page 15 for spider anatomy.) At other times, it moves into an existing burrow after the original owner — perhaps a mouse or a lizard — leaves.

Although tarantulas don’t weave webs, they often line their burrows with silk. They also weave a “welcome mat” of webbing at the burrow’s entrance. When an animal wanders by and steps on the mat, the silk transfers tiny vibrations down inside the hole, like a doorbell alerting the tarantula that someone — food or foe? — has arrived for a visit.

Dining In or Dining Out?

Tarantulas are perfectly happy to let dinner come to them. When an insect strays across the entrance to its burrow, the tarantula lunges out and nabs it, like a middle-schooler plucking a pizza delivery off the front porch.

If dinner doesn’t arrive at its doorstep, the spider has to leave the safety of its burrow and go on the hunt. Because its eight eyes are nearly useless, a tarantula must feel its way around using its pedipalps and sensitive hairs on its legs. Wandering in this way is slow and dangerous. Lizards, birds, and even wolf spiders would love to make these meaty morsels into a meal. 

But when a tarantula encounters a cricket, beetle, or caterpillar, it turns — in an instant — from bumbling prey into a powerful predator. Like an eight-legged lion, the spider pounces and stabs its hollow, half-inch-long fangs into the victim. The needle-sharp teeth inject venom, which quickly kills the prey and turns its insides to mush. This makes it easier for the spider to slurp up. Yum!

Although tarantula venom is deadly to insects, it isn’t harmful to humans. A tarantula bite may make you yell “ouch!” but it won’t leave you any worse off than a bee sting.

A Tarantula’s Worst Nightmare

Who knows if tarantulas have bad dreams? If they do, thoughts of a feisty, electric-blue wasp likely make them toss and turn in their silk-lined beds.

The wasp in question is called a tarantula hawk. Adult wasps don’t eat spiders — they sip nectar for food. But when a mama T-hawk is ready to lay an egg, she buzzes off to catch the biggest spider she can spot.

The 2-inch-long wasp’s business end is tipped with a stinger as long as your pinkie nail. One well-placed poke from this stun gun bun delivers a searing sting that can paralyze a spider in seconds.

When a tarantula feels threatened, it rears up on its back legs and shows off its formidable fangs. If that fails to scare away an attacker, the spider plucks arrow-sharp hairs off its belly and slings them at the threat. The barbed bristles pepper the attacker’s skin and eyes, giving the spider time to scurry away.

Unfortunately, neither the fangs nor the hair-rows usually work on a mama T-hawk. The wasp buzzes around, dodging the spider’s attacks, waiting until she sees an opening. When the spider rears up, the wasp slides under its body, and delivers a fateful sting.

Once the spider stops struggling, the wasp uses hooked spines on her legs to drag the tarantula back to her nest. There she lays a single egg on the unmoving but still living spider. After the egg hatches, the baby wasp will feed on the still-fresh tarantula for nearly a month.

Tarantula-natomy

The chelicerae (keh-liss-air-uh) are a spider’s jaws. They’re tipped with large, sharp fangs that a tarantula uses to defend itself or inject venom into prey. A tarantula’s mouth is hidden under its chelicerae.

Pedipalps look like legs, but a tarantula doesn’t use them to walk. Instead, they help the spider handle food and sense objects it encounters.

Like most spiders, a tarantula has eight eyes but poor eyesight. The eyes can spot movement and tell light from dark, but that’s about it.

Like all spiders, a tarantula has eight legs that it uses to walk. Each leg has seven segments, which makes it really bendy.

The first of two body parts on a spider is called the cephalothorax (sef-uh-loe-thor-ax). The mouth, eyes, and legs are found on the cephalothorax.

The second body part is the abdomen. It contains the digestive tract, lungs, and other important organs.

Liquid silk leaves a spider’s body through the spinnerets. When the silk hits air, it becomes solid and stringy.

Love Hurts

Life for a tarantula is risky. And for males, finding a girlfriend can make life even riskier. Food is food, and tarantulas rarely pass up a meal — even if it happens to be a fellow spider. So when a lovestruck male meets a female, two things can happen: He’ll either find a mate or have the worst (and last) day of his life.

In September and October, males leave their safe, cozy burrows to zigzag over glades and scurry across roads, looking for romance. A male uses his pedipalps to follow a scent trail to a female’s burrow. When he arrives, he taps on the silk around the doorway, hoping to convince the larger female that he isn’t prey. If he’s lucky, the female crawls out of her burrow, and the male lays on the charm by performing an eight-legged tap dance.

Even if the female lets him be her boyfriend, the male still dies within a year after mating. Males rarely make it past their 10th birthday, but females may live longer than 20 years.

Numbers Game

After mating, a mama tarantula spends winter nestled deep in her burrow. The following summer she lays 100 to 1,000 eggs, bundles them up in a silken sack, and hangs the sack on the side of her burrow like a baby hammock.

Around August, tiny tarantulas hatch out of the hammock. The babies are called “slings.” They stay in mom’s burrow, under her protection, until they’ve grown large enough to survive on their own. 

To grow bigger, a tarantula must molt. Instead of bones, spiders have hard plates on the outside of their bodies called an exoskeleton. The exoskeleton is like armor — it doesn’t stretch. So when a spider’s insides outgrow its outsides, the spider pumps fluid into its abdomen, causing the exoskeleton to split open. Once a crack forms, the spider pulls its body out of the old exoskeleton and begins to form a new one. Baby tarantulas shed their exoskeletons every few weeks. After they reach adult size, they rarely molt more than once a year.

Life gets tough for the tiny slings when they leave mom’s burrow. Predators — like lizards and birds — abound, and finding a safe hole of their own takes a heavy toll. That’s why mama tarantulas have so many babies. With luck, a few of them will live long enough to become hairy, not-so-scary, gentle giants.