Scorpions Spiders Mites and Ticks: Arachnida

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.