Spiders, Scorpions, Mites, and Ticks: Arachnida

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SPIDERS, SCORPIONS, MITES, AND TICKS: Arachnida

PHYSICAL CHARACTERISTICS

Arachnids (uh-RAK-nihds) are related to sea spiders and horseshoe crabs. Among the many members of this group are ticks and mites, scorpions, spiders, and even the common harvestman, also known as daddy longlegs—all with their own distinct appearance. Despite these differences, many adult arachnids have two distinct body regions: the front portion, a sort of head area combined with a thorax, or midsection, contains the mouthparts and six sets of paired, leglike limbs, and the second portion, the abdomen, has a stomach, reproductive opening, and lunglike structures or breathing tubes. While arachnids all have these two body parts, some have narrow waists, and others have thick waists. In some arachnids, such as mites and harvestmen, the two body parts are closely joined together to form a single region; the two parts cannot easily be seen as different from each other. The front region of arachnids is covered by a carapace (KARE-a-pays), a smooth, shieldlike plate, which in some arachnids, such as harvestmen and sun spiders, is divided into three parts. In ticks, mites, and most spiders the abdomen is usually smooth, without any segments, but in all other arachnids the abdomen is plainly divided into segments.

Arachnids have mouthparts that look like small pinchers. They are used to capture and chew prey, or food animals. The mouthparts are sometimes used as fangs to inject venom, or poison, and digestive chemicals into the wounds of their prey. Arachnids also have a small set of leglike structures, called pedipalps, attached to either side of the mouth; in some arachnids these are used to cut and crush food, and, in others, they serve as antennae. Adult arachnids all have four pairs of legs. The legs often have bristles (brih-SUHLS), or short, stiff hairs, that can sense vibrations (vie-BRAY-shuns). The first pair is sometimes not used for walking at all and is used instead as feelers, or antennae. The other three pairs of legs are used for walking and digging, as well as for capturing prey. Some arachnids have fingerlike projections on their abdomens, used to produce silk; in spiders these structures are called spinnerets. Some arachnids have additional sensory equipment on their abdomens. Whip scorpions have a bristly and sensitive whiplike tail on the tip of the abdomen, and scorpions have comblike structures underneath the abdomen, used to detect vibrations.

GEOGRAPHIC RANGE

Arachnids are found throughout the world. About eight thousand of the ninety-seven thousand species of arachnids are found in the United States and Canada.

HABITAT

Arachnids live on land, in nearly every sort of habitat. Some live in freshwater.

DIET

Arachnids attack and kill small animals, especially insects and their relatives, and then feed on their body fluids. Many ticks and mites are parasites, meaning that they feed on the blood and tissue fluids of their victims without necessarily killing them. Some mites take the fluids and tissues of plants and funguses. Unable to chew, most arachnids must first digest their food outside their bodies. They pierce tissues with their mouthparts and inject them with digestive chemicals, turning them into fluids. The fluids are then sucked through the mouth and into the body.

BEHAVIOR AND REPRODUCTION

Most arachnids live alone, except during the mating season. They engage in an amazing variety of activity to obtain food. Some spiders trap their victims in silken webs and kill them with a poisonous bite. Others ambush their prey and overpower them with their strong legs before biting them. Scorpions use their claws to capture and kill prey, or else they kill them with a venomous sting. Pseudoscorpions (SOU-doh-skor-pee-uhns) lack a stinger, but they have claws with poison glands that drip venom into the wounds of their victims. Sun spiders use lightning speed and their massive mouthparts to outrun and tear apart prey. Ticks climb up on grass and brush along trails, spreading their legs like grappling hooks to latch on to the fur or clothing of hosts walking nearby. Mites lack the ease of movement that would allow them to travel long distances in their search for food, so some species attach themselves to larger animals not as parasites but as hitchhikers, to help them get around to find food.

When they are ready to mate, male arachnids transfer sperm, or male reproductive cells, either to special parts of the leglike organs of the mouth or onto the ground in "packets." Eventually, the sperm is moved to or picked up by the female during courtship, a set of activities meant to attract a mate. Some scorpions and other arachnids can reproduce without males. There may be one, to more than one thousand, eggs in a single brood. The eggs are laid in underground chambers, beneath stones, under tree bark, enclosed in a silken cocoon, or held in a sticky sack beneath the body of the female. Some scorpions have live young, while others keep their eggs inside the body until they hatch. Some female arachnids guard their eggs or young until their first molt, when the young shed and replace their outer covering, or exoskeleton, for the first time. Young arachnids always resemble tiny adults, although some mites hatch with only six legs and gain an additional pair as they grow into adulthood.

SMOOTH AS SILK?

Spider silk is a liquid protein played out as dry fibers through spigots mounted on six abdominal faucetlike structures called spinnerets. The spinnerets form a pump-and-valve pressure system that allows spiders to change the thickness, strength, and stretchiness of their silk. Certain kinds of spiders, called cribellate (KRIB-uh-layt) spiders, have a special plate, called the cribellum, that produces webs made up of wooly strands of silk that are sticky, like Velcro. Ecribellate (EE-krib-uh-layt) spiders lack this plate and produce webs that are tacky by virtue of glue droplets strung out like pearls along the silken strands.

ARACHNIDS AND PEOPLE

Spiders help control insect pests in gardens and parks and among field crops. Some mites eat other mites and are used to control the populations of mites that harm crops. However, many ticks and mites act as parasites on people and other animals and spread diseases. Despite their reputation, only a few spiders and scorpions have venoms strong enough to harm people. The venomous bites and stings of such spiders and scorpions are dangerous to humans, especially young children, elderly persons, or people who are already in poor health.

CONSERVATION STATUS

The World Conservation Union (IUCN) lists one arachnid species as Endangered, meaning that it faces a very high risk of extinction in the wild in the near future; nine as Vulnerable, meaning that there is a high risk of its extinction in the wild; and one as Near Threatened, meaning that it is at risk of becoming threatened with extinction in the future. These and other species of arachnids are threatened by habitat destruction.

HAIR FOLLICLE (FAH-LIH-KUHL) MITE (Demodex folliculorum): SPECIES ACCOUNTS

Physical characteristics: This microscopic, wormlike, almost transparent, or see-through, parasitic mite is 0.00394 to 0.0178 inches (0.1 to 0.45 millimeters) in length. The head is distinctly separated from the body. The abdomen is finely wrinkled and tapered. Adults have eight stumplike legs, each with claws. The needlelike mouthparts are used for eating skin cells.

Geographic range: These mites live worldwide, wherever people live.

Habitat: This mite lives in human hair follicles, the small sacs that surround the root of each hair. The mite might be found anywhere on the body but prefers the follicles of the face, the roots of eyelashes, and the oil glands of the forehead, nose, and chin.

Diet: The hair follicle mite eats human skin cells.

Behavior and reproduction: Follicle mites are common parasites and spend their entire lives on their human hosts. They live in hair follicles and eyelashes, burrowing head first into the root. They move onto the skin at night at rate of 0.4 inches (1 centimeter) per hour.

Females may lay up to twenty-five oval eggs on one hair follicle. Young mites resemble adults. First-stage larvae (LAR-vee), or young mites, are legless, but later stages, before the mite becomes an adult, have six legs. Follicles may become tightly packed as the mite larvae grow. Adult mites leave follicles to mate and then find new follicles in which to lay eggs. The entire life cycle of the mite, from egg to adult, takes about fourteen to eighteen days.

Hair follicle mites and people: Mites are basically harmless, and humans who harbor them often show no signs of infestation. Follicle mites are not known to transmit diseases, but large numbers in a single follicle may cause itching and other skin disorders, especially in the elderly.

Conservation status: This species is not endangered or threatened. ∎

ROCKY MOUNTAIN WOOD TICK (Dermacentor andersoni): SPECIES ACCOUNTS

Physical characteristics: Adult wood ticks typically measure 0.08 to 0.21 inches (2 to 5.3 millimeters) in length, but females filled with blood look like plump beans and may reach a length of 0.65 inches (16.5 millimeters) and a width of 0.45 inches (11.4 millimeters). Their flat, pear-shaped bodies are covered with a tough outer skeleton.

Adult females are reddish brown with a grayish white shield on the back, near the front of body; the shield turns grayish when it fills with blood. Males are spotted with brown and gray and do not have a distinctive white shield. There are eleven folds along the edge of the abdomen.

Geographic range: The Rocky Mountain wood tick is widely distributed in North America, primarily throughout Rocky Mountain states and into southwestern Canada.

Habitat: This tick is found in spring and summer in brushy areas of foothills and mountains that are home to small mammals.

Diet: Wood ticks at the adult and larval stages feed as external parasites on the blood of reptiles, birds, and mammals and can survive for more than one year without feeding at all. When they find a host, males feed for about five days without becoming engorged, or completely filled with blood. Then they become sexually mature and ready to mate; after mating they resume feeding. Females feed for up to seven days (until they are fully engorged), during which time they mate. The body weight of a fully engorged female will increase from about 0.000176 ounces (5 milligrams) to more than 0.0247 ounces (700 milligrams).

Behavior and reproduction: Adults infest and live as parasites on large animals, such as bear, sheep, cattle, horses, dogs, and humans. Young ticks are called larvae or nymphs. Larval ticks have only six legs, while nymphs have all eight. The larvae and nymphs feed on smaller mammals, including rabbits and squirrels. Insects at all stages attack jackrabbits and porcupines. Larvae, nymphs, and adults climb grass stems and bushes while searching for a host animal. They use carbon dioxide and other chemicals associated with mammals to detect the presence of potential hosts. Ticks attach themselves to their hosts by secreting, or giving off, a special kind of glue around their mouthparts just before inserting them into the host's flesh. Only immature ticks and adult females become engorged with the host's blood. Engorged larvae, nymphs, and unfed adults normally spend the cold winter months in grasses and leaf litter.

Ticks require a blood meal before they can molt; this is also a necessity for their eggs to develop. Mating usually takes place on the host animal. After she finishes feeding, the mated female leaves the host and looks for a protected place to lay her eggs. She lays up to 7,400 eggs over a period of ten to thirty-three days and then dies. The six-legged larvae hatch and begin to search for chipmunks, mice, voles, and other small rodents. If they do not find a host within a month, they die. They feed on their first host for two to eight days before dropping to the ground and molting. At this stage they can often survive for more than year without feeding again. With their full complement of eight legs, the tick nymphs seek slightly larger hosts, such as rabbits, ground squirrels, marmots, and skunks, and feed on them until they become engorged in three to eleven days. They drop off to molt into adults in about two weeks. Adults can survive nearly two years without feeding. After finding an even larger host, partially fed adults are ready to mate.

Rocky Mountain wood ticks and people: Females may carry and transmit several diseases from small mammals to humans, including Rocky Mountain spotted fever, tularemia, and Colorado tick fever in the United States. This happens only rarely in Canada.

Conservation status: This species is not endangered or threatened. ∎

TAILLESS WHIP SCORPION (Phrynus parvulus): SPECIES ACCOUNTS

Physical characteristics: Whip spiders, or tailless whip scorpions, grow as long as 1.2 inches (30.4 millimeters). They lack the ability to produce silk and do not have venom glands. Their claws fold into a spiny basket, used to capture and hold prey. Young whip scorpions have reddish pedipalps and striped legs; the adults are uniformly brownish. The undivided carapace is wider than it is long. The first pair of legs is long, slender, and whiplike. Packed with special sensory structures, these legs are used not for walking but as antennae, or sense organs. The abdomen lacks a tail or defensive glands. The front of the body and abdomen are attached to each other by a narrow waist.

Geographic range: These scorpions range through Belize, Guatemala, and Costa Rica.

Habitat: Tailless whip scorpions live in cracks and crevices (KREH-vuh-ses) between rocks, under loose tree bark, at the base of tree trunks, or inside animal burrows, caves, and tree holes.

Diet: Tailless whip scorpions prey on small crickets, moths, and millipedes but usually avoid scorpions, centipedes, large spiders, and most ants.

Behavior and reproduction: Tailless whip scorpions are solitary animals. They are often found sitting quietly on tree trunks, waiting for insects to pass by and waving their whiplike pedipalps back and forth. Tailless whip scorpions are gentle creatures. They are very shy and run quickly when threatened. If they are attacked, they will use their spiny pedipalps as defensive weapons.

When females are nearby, males will often engage other males in combat, locking their mouthparts and claws together in battles that may last more than an hour. Males and females engage in a courtship dance that includes lots of touching and brief grabbing with the pedipalps. Once the male is accepted as a mate, he deposits a sperm packet and guides the female over it. The female lays twenty to forty eggs several months after mating. The eggs are carried underneath the body of the female until they hatch in about three or four months. After hatching, the young crawl up on the mother's back, where they remain for about a week, until they molt. They molt once or twice a year until they reach maturity. Tailless whip scorpions continue molting and growing throughout their adult lives.

Tailless whip scorpions and people: Tailless whip scorpions lack venom and are quite harmless.

Conservation status: These scorpions are not endangered or threatened. ∎

COMMON HARVESTMAN (Phalangium opilio): SPECIES ACCOUNTS

Physical characteristics: The small, round bodies of common harvestmen are 0.14 to 0.35 inches (3.5 to 8.9 millimeters) in length; males typically are smaller than females. The back has various patterns and ranges in color from light gray to brown, while the underside is usually light cream colored. Both body regions are divided into segments and are joined together. Two eyes directed outward are located on top of the front body region. The common harvestman has eight very long, thin legs. These insects lack venom glands and the ability to produce silk.

Geographic range: The common harvestman lives in North America, Europe, and the temperate regions, or regions with a mild climate, of Asia.

Habitat: The common harvestman is found in gardens, parks, vacant lots, forests, woodlands, and agricultural areas.

Diet: Harvestmen feed on small, soft-bodied invertebrates (in-VER-teh-brehts), or animals without backbones, such as aphids, caterpillars, leafhoppers, beetle larvae, mites, and slugs. They also feed on dead invertebrates and decaying plant materials, such as rotted fruit.

Behavior and reproduction: Harvestmen are active in summer and fall. At night they sometimes gather in large groups on the trunks of trees, with their legs intertwined. They fend off predators (PREH-duhters), or animals that hunt them for food, with a smelly, harmless fluid from scent (SENT) glands located between the first and second pairs of legs. When they are attacked, harvestmen will purposely detach a leg. The twitching limb distracts the predator until the harvestman can escape. The lost leg cannot be replaced.

Mating takes place face to face, with the male placing sperm directly into the female's body. Females lay clusters of ten to several hundred eggs in moist areas on the ground, under rocks, in cracks in soil, or in leaf litter in the autumn. One or two generations of insects are produced each year. The young hatch in spring. They look very much like the adults but have slightly shorter legs in proportion to their body size. They usually undergo seven molts, reaching maturity in two to three months.

Harvestmen and people: Harvestmen help control insect and mite pests that feed on cultivated crops. They are harmless to humans.

Conservation status: This species is not endangered or threatened. ∎

ZEBRA JUMPING SPIDER (Salticus scenicus): SPECIES ACCOUNTS

Physical characteristics: The stout-bodied adult zebra jumping spider ranges in size from 0.20 to 0.32 inches (5.1 to 8.1 millimeters). The two body regions are not segmented and are attached to each other by a narrow waist. The body is black with white hairs that form stripes on the abdomen. The eight legs are rather short and covered with sensory hairs. The fangs are large and usually hidden by the leglike mouthparts. Males are similar in appearance to females, but they have larger fangs, a darker body, and brightly colored bristly brushes on their pedipalps. Their eight eyes are arranged in three rows of four, two, and two. Jumping spiders have binocular vision: two of their eight eyes are very large and pointed directly forward, making them capable of focusing on a distant object. Binocular vision allows jumping spiders to accurately determine the distance of prey or another object. The large eyes of jumping spiders are capable of slight movement to adjust focus or to scan the scene without having to change body position. Their legs are not especially enlarged for jumping.

Geographic range: The zebra jumping spider ranges throughout the Northern Hemisphere, including most of Europe and the United States.

Habitat: This species is common in gardens, on rocks, stones, flowers, plant foliage, grass, and occasionally on trees. They are often found on vertical surfaces, such as walls, fences, decks, patios, and doorways.

Diet: They eat mostly small insects and spiders.

Behavior and reproduction: Jumping spiders jump more than they walk, and they can do so forward, sideways, and backward with equal ease and speed of movement. They do not use webs to capture their food but instead actively hunt their prey throughout the day. These spiders can catch prey up to twice their own body length, spotting them as far away as 8 feet (2.4 meters). They slowly stalk and pounce upon their prey from as far away as 6 inches (15.2 centimeters). Before jumping, the spider plays out a strand of silk and attaches it to the ground or to a branch or leaf as a safety line. Using its fangs, the spider delivers both venom and digestive chemicals. The prey is then chewed up with the spider's powerful mouthparts, and its body fluids are sucked into the spider's mouth.

Jumping spiders also build a silken cocoon or retreat into crevices, under stones and bark, or on foliage. Retreats are used as hiding places at night or shelters for molting, feeding, protecting young, and hibernation (high-bur-NAY-shun), a period of inactivity during the winter.

Before mating, males must first transfer sperm to special chambers on their leglike mouthparts. Males then court females with an elaborate and colorful display of leg waving. This dance is intended, in part, to identify the male as a potential mate for the female and not a meal. If she is willing, the male attempts to deposit the sperm into an opening underneath the female's abdomen. Females lay their eggs in silken shelters and guard them until they hatch and molt for the second time. Zebra jumping spiders mature in late spring or summer and live for about one year.

Zebra jumping spiders and people: Although the species is considered a nuisance around homes and buildings, these spiders are harmless to humans and probably eat many insects that are considered pests.

Conservation status: This species is not endangered or threatened. ∎

LONG-BODIED CELLAR SPIDER (Pholcus phalangioides): SPECIES ACCOUNTS

Physical characteristics: The grayish brown or tan body of the cellar spider is slender and measures 0.23 to 0.3 inches (6 to 8 millimeters) in length. These spiders have eight long, clear legs. The body regions are not divided into segments and are attached to each other by a thin waist. Males are slightly shorter than females. The abdomen is long and rectangular.

Geographic range: Long-bodied cellar spiders are found throughout world, especially in the United States and Europe.

Habitat: Long-bodied cellar spiders are usually found in homes and nearby buildings. They prefer dark, damp areas, such as crawl spaces, basements, closets, sink cabinets, ceilings, cellars, warehouses, garages, attics, and sheds. They also spin webs near open doors and windows that allow flying insects to enter. Spiders hang upside down in messy, irregular webs shaped something like umbrellas.

Diet: This species eats almost any kind of insect or spider that becomes trapped in its web.

Behavior and reproduction: Prey trapped in the web either is eaten immediately or is swiftly wrapped in silk, like a mummy. The prey is bitten, injected with digestive chemicals, and then sucked dry over the next day or so. The cellar spider also invades other webs, kills the resident spider, and claims the web as its own. When these spiders are threatened, they violently shake their webs.

Courtship may take several hours, ending when the male transfers his sperm from his leglike mouth structures to the female's reproductive organs. Females produce up to three clear egg sacs, each with thirteen to sixty eggs. The sac is carried in the female's mouth. The female guards the eggs for several weeks, until they hatch. The young resemble the adults and soon strike out on their own to build their own webs nearby. They molt five times before reaching maturity and live for about two years.

Long-bodied cellar spiders and people: Urban legend has it that the venom of this spider is one of the most deadly of all, but the small and weak mouthparts prevent this spider from injecting a lethal dose to human victims. Their fangs are too small to puncture human skin, and their venom is not very strong and not dangerous to people. Cellar spiders are beneficial, in that they capture and eat household insects and other spiders.

Conservation status: This species is not endangered or threatened. ∎

BOOK SCORPION (Chelifer cancroides): SPECIES ACCOUNTS

Physical characteristics: The book scorpion is very small, at 0.10 to 0.18 inches (2.6 to 4.5 millimeters), and looks somewhat like a pear-shaped scorpion without the stinging tail. The front of the body is olive brown to dark red and has no segments. The abdomen is olive green to pale brown and has distinct segments. The body regions are attached to one another. Their tiny claws contain venom glands.

Geographic range: The book scorpion is found throughout most of Europe and the United States.

Habitat: They are commonly found in homes and other buildings, including stables, barns, grain stores, and factories. They are also often found in old books in libraries.

Diet: The book scorpion eats insects, mites, and lice. Prey is grabbed, killed, and torn apart with the pedipalps, which contain venom glands. The body fluids of the prey are then sucked into the mouth.

Behavior and reproduction: Books scorpions are sometimes found in large groups, with several dozen individuals. Females often use their pedipalps to grab hold of flying insects, such as house flies, to hitch a ride. Males are less likely to use this method of transportation. Their clawed pedipalps are used primarily for defense, fighting, prey capture, and building nests. Silk produced by glands in the claws is fashioned into a cocoon for molting and winter hibernation.

Book scorpions engage in courtship dances. The male grabs the female's claws and legs and leads her to his sperm packet. Females brood sixteen to forty eggs in a sac attached underneath their bodies. The young resemble the adults but are much paler. They molt three times and take from ten months to two years to reach maturity. They may live three to four years.

Book scorpions and people: Book scorpions eat head lice, mites, ants and other small arthropod pests living in homes and other buildings, but humans seldom notice them at all.

Conservation status: This species is not endangered or threatened. ∎

CAMEL SPIDER (Galeodes arabs): SPECIES ACCOUNTS

Physical characteristics: Camel spiders are yellowish and have a leg span up to 4.7 inches (119 millimeters), but their bodies are only 2 inches (51 millimeters) long. Males are usually smaller and more slender than females and have longer legs. Both regions of the body are divided into segments. Their entire bodies are covered with hairlike bristles. They have two small eyes set on a small bump near the front of the body. Up to one-third of the body length consists of their pincherlike mouthparts. The long and slender leglike mouthparts, as well as the first pair of legs, look and function like antennae.

Geographic range: The camel spider lives in northern Africa and the Middle East.

Habitat: This species lives in sandy, hot, and dry habitats.

Diet: Camel spiders eat small mice, lizards, birds, amphibians, spiders, scorpions, and insects, especially termites. They use their large, powerful mouthparts to crush prey and drink water.

Behavior and reproduction: Camel spiders spend their days hiding beneath objects or in shallow burrows dug with their legs and mouthparts. They usually come out at night to hunt, locating prey with their leglike mouthparts on the ground or beneath the surface of the earth, through ground-level vibrations. Amazingly fast on their feet, camel spiders can run, in very short bursts, up to 20 inches (51 centimeters) per second, using only the back three pairs of legs.

In mating, the male roughly seizes the female with his legs and mouthparts, but he does not injure her. She becomes motionless, which prevents her from attacking the male and eating him. The male carries the female for a short distance, places her on her back, and begins stroking the underside of her abdomen. He then produces a sperm packet, picks it up in his mouth, and places it inside her body. Later, the female deposits up to 164 eggs in a deep burrow. The eggs hatch within a few days into nonmoving creatures that do not resemble the adults and do not feed. After their second molt, they begin to look more like adults, leave the burrow, and start to hunt.

Camel spiders and people: Camel spiders are not venomous and are not considered dangerous to people. In the past one hundred years soldiers stationed in North Africa and the Middle East have been fascinated by these large, fast arachnids, sometimes staging battles between captive animals.

Conservation status: This species is not endangered or threatened. ∎

GIANT WHIP SCORPION (Mastigoproctus giganteus): SPECIES ACCOUNTS

Physical characteristics: Whip scorpions, also known as vinega-roons, mule killers, or grampas, are dark reddish brown or brownish black and measure 1 to 3.2 inches (25 to 80 millimeters) without the long, whiplike tail. The tail is usually carried straight over the back, lacks a stinger, and, at its base, has glands that release strong, defensive acids that smell like vinegar. The body is divided into two regions. The front region is undivided and covered by a carapace. It is attached to the segmented abdomen by a narrow waist. There is one pair of eyes at the front of the body, with three more pairs of eyes on the sides. The thick, spiny claws are used to grasp, tear, and place food into the mouth. There are four pairs of legs. The first pair is long and slender and used like antennae, while the remaining legs are used for walking. Males and females are very similar in appearance, but the claws of the male are slightly longer and more slender, while they are somewhat shorter and stouter in the female.

Geographic range: The giant whip scorpion lives in the southern United States, from southeastern Arizona east to Florida and northern Mexico.

Habitat: Giant whip scorpions prefer dark, humid places and avoid bright sunlight whenever possible. They hide during the day in burrows under logs, rotting wood, rocks, and other natural debris.

Diet: Giant whip scorpions eat many different kinds of crawling invertebrates.

Behavior and reproduction: Whip scorpions hunt actively at night, using their sensitive front legs to detect ground vibrations triggered by the movements of prey. They attack and overpower prey with their mouthparts and claws. Although they are very slow, gentle animals, whip scorpions can move quickly when threatened and will squirt acid that weakens the exoskeletons of other arthropods. They will also use their claws to pinch their enemies.

Courtship involves a mating dance. The male grasps the female's antennalike front legs with his mouthparts and grabs her claws with his; then he guides her over to his sperm packet. He may assist her by placing the sperm packet directly into her reproductive opening with his claws. Afterward, the female finds a sheltered spot and produces a batch of eggs in a clear sac and carries them under her abdomen until they hatch. The pale, nearly transparent, young climb onto the mother's back and remain there until the next molt. Then they climb down to strike out on their own. They molt once a year and take three to four years to reach adulthood.

Giant whip scorpions and people: Whip scorpions are not venomous, but they are capable of spraying a mist of concentrated acetic (uh-SEE-tik) acid, the primary ingredient of vinegar. Larger individuals can inflict a painful pinch. Giant whip scorpions are sometimes kept as pets and are popular animals in insect zoos.

Conservation status: This species is not endangered or threatened. ∎

EMPEROR SCORPION (Pandinus imperator): SPECIES ACCOUNTS

Physical characteristics: Emperor scorpions are shiny blue, black to greenish black, and measure 5 to 8 inches (127 to 203 millimeters) in length, including the tail. They weigh up to 1.1 ounces (35 grams), although pregnant females may weigh as much as 1.4 ounces (40 grams). The males are similar in appearance to the females, but are slightly smaller and lighter-bodied. The powerful reddish-brown claws are rough in texture. The claws, body, and tail are covered with sensory hairs. Underneath the abdomen, behind the last pair of legs, is a pair of comblike pectines. The pectines of males are longer than those of females. The six-segmented tail ends in a curved stinger.

Geographic range: This species is found in the western African countries of Senegal, Guinea-Bissau, Guinea, Ivory Coast, Sierra Leone, Ghana, Togo, Democratic Republic of Congo, Nigeria, Gabon, and Chad.

Habitat: This species prefers living in hot, humid habitats. They live in abandoned burrows of other animals or will dig their own. Individuals will also take shelter beneath rocks, logs, and tree roots.

Diet: They will hunt almost any animal smaller than themselves. Their food includes crickets, insects, other arachnids, mealworms, and millipedes. They will even catch and kill small mice and lizards. Emperor scorpions seldom run down their prey, preferring instead to ambush unsuspecting insects and other small animals that wander nearby. Digestive chemicals are used to turn their victim's tissues into liquid, which is then sucked into the mouth.

Behavior and reproduction: Emperor scorpions search for mates and hunt for food at night. They detect the size and location of prey mainly through vibrations in the ground and in the air. Hungry scorpions move slowly forward, with open claws held out, and tail raised forward over the body. Young scorpions grasp their prey with their claws and quickly sting it. Larger adults crush and kill their victims with their large and powerful claws. Adults are unusually calm and very slow to sting in defense and seldom inject venom when they do.

Adult males spend most of their time looking for mates. During courtship the male uses his claws to grasp those of the female. He guides her to a hard surface where he deposits his sperm packet. He then pulls the female over the sperm packet so she can pick it up with her reproductive organs. The male leaves soon after courtship is completed to avoid being killed and eaten by a hungry female.

The female gives live birth. The young are carried inside her body from seven to nine months. Anywhere from nine to thirty-five pale white scorpions are born, one after the other. They will climb up on the mother's back and remain there until their first molt. They molt about seven times in four years before reaching adulthood. Adult females often continue to live with their young and will sometimes eat them if other kinds of food are not available. The bodies of young scorpions become darker as they grow. Their total life span is about eight years.

Emperor scorpions and people: Although large in size, emperor scorpions are not considered dangerous to healthy humans. The venom is very mild, but the sting can still be painful. Young scorpions and adult females are more likely to sting than adult males. Larger individuals can deliver a painful pinch with their claws. They are commonly sold as pets and are frequently used in films as "deadly" animals.

Conservation status: This species is not listed by the World Conservation Union (IUCN). However, because thousands of individuals are collected and sold in the pet trade every year, they have been listed as Threatened on Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Their populations are being monitored to prevent over collecting. ∎