Amazing Arachnids: Whip Spiders

Adapted from pages 88-90 of Amazing Arachnids:

Imagine a world of giant horsetail trees, ferns, and clubmosses. Everything looks oddly familiar, but dramatically out of scale. Plants that you think of as being only a few inches in height are now tall trees. Huge dragonflies with 2-foot (0.6 m) wingspans hunt in the air, while 4-inch-long (10 cm) cockroaches and 2-foot-long (0.6 m) millipedes feed on the abundant decaying plant material on the forest floor. Small reptiles forage among the vegetation, and occasionally one is drowned in the water-filled stump of a clubmoss tree. Lurking in the swampy pools are large, salamander-like amphibians. This is the world of the Carboniferous Period 300 million years ago, and in this world another predator lived. This flat, spiderlike creature stalked its prey on vertical surfaces, tentatively bending its antenniform feelers around curves as it hunted. These feelers were in fact modified legs but were no longer used for locomotion. They had become long and thin, and articulated with many joints, forming the elegant structure that gives this arachnid its common name “whip spider.”

Whip spiders possess a diverse array of cuticular sensory structures on their antenniform legs. Among the hairs (or setae) are bristles, club sensilla, porous sensilla, rod sensilla, leaflike hairs, and trichobothria. In addition to the setae, there may be other structures present, including a pit organ, a plate organ, and slit sensilla. Among the most numerous of these cuticular sensory setae are bristles. Bristles are most likely contact chemoreceptors, able to “taste” chemical traces via an open pore at the tip of each bristle. These bristles are arranged in 5 evenly spaced rows around the circumference or the tarsi and may range in number from almost 500 in the protonymph to more than 1,500 in the adult. Approximately 500 club sensilla may also be involved in chemoreception, primarily in olfaction, as are the porous sensilla consisting of hairs perforated by numerous pores. Among mechanoreceptors are the trichobothria, the leaflike hairs, and the slit sensilla. In whip spiders, the long delicate trichobothrial hairs are found on the tibia of the whip as well as on the tibia of the walking legs. These, as well as the slit sensilla, provide long-distance mechanoreception, extremely important in detecting moving prey. In fact, the walking legs provide an important backup in this crucial aspect of hunting.

Two long, slender antenniform legs characterize amblypygids, giving them the name “whip spider.” These legs are no longer used for locomotion but are sensory in function. The antenniform legs
are also essential in intraspecific communication.

Even if the whip spider has lost both antenniform legs, it can still find and capture prey successfully by using the trichobothria on the walking legs; however, the whip spider absolutely must have trichobothria in order to locate moving prey. Once potential prey has been detected, the amblypygid orients itself facing toward it and unfolds its raptorial palps in preparation for the capture as it approaches the quarry. With a sudden lunge, the prey is grasped with the armed palps. Perhaps because whip spiders possess no venom and are somewhat delicate in physical structure, the creatures they capture are usually smaller than themselves. Crickets, moths, small lizards, and small frogs have been documented as prey of whip spiders in the wild. Once the prey has been captured, the whip spider uses its chelicerae to tear a hole in the body wall and regurgitates digestive juices into the opening. The chelicerae continue to masticate the prey into an amorphous mush while the digestive fluids break down the tissue. Like most other arachnids, the whip spider ingests only liquefied food, filtering out solid particles as the powerful phyrangeal pump and stomach suck in the predigested meal.

Amazing Arachnids
By Jillian Cowles

The American Southwest is home to an extraordinary diversity of arachnids, from spitting spiders that squirt silk over their prey to scorpions that court one another with kissing and dancing. Amazing Arachnids presents these enigmatic creatures as you have never seen them before. Featuring a wealth of color photos of more than 300 different kinds of arachnids from eleven taxonomic orders–both rare and common species—this stunningly illustrated book reveals the secret lives of arachnids in breathtaking detail, including never-before-seen images of their underground behavior.

Amazing Arachnids covers all aspects of arachnid biology, such as anatomy, sociality, mimicry, camouflage, and venoms. You will meet bolas spiders that lure their victims with fake moth pheromones, fishing spiders that woo their mates with silk-wrapped gifts, chivalrous cellar spiders, tiny mites, and massive tarantulas, as well as many others. Along the way, you will learn why arachnids are living fossils in some respects and nimble opportunists in others, and how natural selection has perfected their sensory structures, defense mechanisms, reproductive strategies, and hunting methods.

  • Covers more than 300 different kinds of arachnids, including ones new to science
  • Features more than 750 stunning color photos
  • Describes every aspect of arachnid biology, from physiology to biogeography
  • Illustrates courtship and mating, birth, maternal care, hunting, and defense
  • Includes first-ever photos of the underground lives of schizomids and vinegaroons
  • Provides the first organized guide to macroscopic mites, including photos of living mites for easy reference
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