Amazing Arachnids: Jumping Spiders

Adapted from pages 236-247 of Amazing Arachnids:

Jumping spiders have so many pleasing qualities that it would be difficult to decide what is most admirable about these delightful little creatures. Shimmering iridescence and rich, velvety colors equal the beauty of birds and butterflies. Their fearless capture of prey and their acrobatic leaps surprise and astonish us. Their complex courtship song and dance pique our curiosity. But perhaps the most endearing aspect of jumping spiders is their enormous, forward-facing eyes, gazing at us with every appearance of intelligence and inquisitiveness.

These large, forward-facing eyes, called anterior median eyes, are indeed the key characteristic of this diurnal hunter. Jumping spiders locate their prey visually, stalking and pouncing on it like tiny cats. Unlike vertebrate systems in which one pair of eyes handles depth perception, motion detection, and detail resolution, the spider’s 4 pairs of eyes divide these tasks. Collectively, their 8 eyes create a visual system that rivals any other arthropod’s vision.

Habronattus hallani male. This species of
Habronattus is found throughout a large part of the western United States and into Mexico. It is also primarily a ground hunter.

The force of the grip is due to physical adhesion, not to suction cups or electrostatic forces. If two glass slides are overlapped with a thin film of water between them, they are difficult to pull apart because of the capillary force of the water. The scopula hairs of the spider utilize these extremely strong capillary forces. Apparently the water available in the atmosphere and on surfaces provides the necessary thin film for the end feet to grip the surface. This explains why spiders with scopula hairs can walk sure-footedly on vertical surfaces and upside down, even on glass surfaces. In jumping spiders, the tips of the tarsi (feet) have such dense claw tufts of scopula hairs that they appear to have fuzzy “toes.”

Jumping spiders make up the most diverse family of arachnids in the world, with approximately 6,000 species described so far. As one might expect with such diversity, some jumping spiders have evolved behaviors that fill extremely specialized niches. One jumping spider in Africa, Evarcha culicivora, prefers to feed on bloodfilled female mosquitoes, especially mosquitoes of the genus Anopheles, famous for spreading malaria. Another salticid, Phyaces comosus from the bamboo areas of Sri Lanka, specializes in predating the eggs and hatchlings of other jumping spiders. It is so tiny and so closely resembles a bit of dirt or debris that it can sneak into the nest of another jumping spider undetected. Yet another species, Bagheera kiplingi from Central America, has a primarily vegetarian diet—unique in the spider world. It lives in acacia trees that produce little nubbins of protein and fat from their leaf tips, as well as nectar from the base of the leaves. These provide food for the ants that in return guard the tree from caterpillars and other herbivores. The jumping spider steals the nubbins and nectar despite the ant patrols, living almost entirely on this vegetable source of protein.

In conclusion, jumping spiders rival any other group of creatures for their beauty, diversity, and complex behaviors. A combination of natural selection with sexual selection has produced an array of stunningly beautiful and surprisingly intelligent predators. The world is a richer place thanks to these diminutive gems.

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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