Jumping Spiders
family of suborder “Typical Spiders“
1 family, 2 species
Jumping spiders are unique due to their distinctive eye patterns and cephalothorax shape. Their front legs are larger than their hind legs, aiding in grasping prey and species recognition signaling. These spiders have eight eyes, with the front row of four being the most prominent and adapted for detailed, three-dimensional vision. They use their silk for safety lines while jumping and build shelters for molting, storing eggs, and sleeping. Jumping spiders have excellent vision, with their anterior median eyes having high resolution and the ability to detect color and UV light.
Hierarchy
species of family “Jumping Spiders“
1 species
Description#
Jumping spiders are among the easiest to distinguish from similar spider families because of the shape of the cephalothorax and their eye patterns. The families closest to Salticidae in general appearance are the Corinnidae (distinguished also by prominent spines on the back four legs), the Oxyopidae (the lynx spiders, distinguished by very prominent spines on all legs), and the Thomisidae (the crab spiders, distinguished by their front four legs, which are very long and powerful). None of these families, however, have eyes that resemble those of the Salticidae. Conversely, the legs of jumping spiders are not covered with any very prominent spines. Their front four legs generally are larger than the hind four, but not as dramatically so as those of the crab spiders, nor are they held in the outstretched-arms attitude characteristic of the Thomisidae. In spite of the length of their front legs, Salticidae depend on their rear legs for jumping. The generally larger front legs are used partly to assist in grasping prey, and in some species, the front legs and pedipalps are used in species-recognition signaling. The jumping spiders, unlike the other families, have faces that are roughly rectangular surfaces perpendicular to their direction of motion. In effect this means that their forward-looking, anterior eyes are on “flat faces”, as shown in the photographs. Their eye pattern is the clearest single identifying characteristic. They have eight eyes, as illustrated. Most diagnostic are the front row of four eyes, in which the anterior median pair are more dramatically prominent than any other spider eyes apart from the posterior median eyes of the Deinopidae. There is, however, a radical functional difference between the major (anterior median) eyes of Salticidae and the major (posterior median) eyes of the Deinopidae; the large posterior eyes of Deinopidae are adapted mainly to vision in dim light, whereas the large anterior eyes of Salticidae are adapted to detailed, three-dimensional vision for purposes of estimating the range, direction, and nature of potential prey, permitting the spider to direct its attacking leaps with great precision. The anterior lateral eyes, though large, are smaller than the anterior median eyes and provide a wider forward field of vision. The rear row of four eyes may be described as strongly bent, or as being rearranged into two rows, with two large posterior lateral eyes being the furthest back. They serve for lateral vision. The posterior median eyes also have been shifted out laterally, almost as far as the posterior lateral eyes. They are usually much smaller than the posterior lateral eyes and there is doubt about whether they are at all functional in many species. The body length of jumping spiders generally ranges from 1 to 25 mm (0.04–0.98 in). The largest is Hyllus giganteus, while other genera with relatively large species include Phidippus, Philaeus and Plexippus. In addition to using their silk for safety lines while jumping, they also build silken “pup tents”, where they take shelter from bad weather and sleep at night. They molt in these shelters, build and store egg cases in them, and also spend the winter in them. Their body’s sensory hairs are able to detect airborne acoustic stimuli up to 3 m away.
Vision#
Jumping spiders have four pairs of eyes; three secondary pairs that are fixed and a principal pair that is movable. The posterior median eyes are vestigial in many species, but in some primitive subfamilies, they are comparable in size with the other secondary eyes and help to detect motion. While unable to form images, the reduced pair of eyes is thought to have a role similar to that of insect ocelli by receiving light from the sky. The photoreceptors in the other secondary pairs are almost exclusively green-sensitive, but the posterior median eyes have two visual opsins different from those in all the other eyes, sensitive to blue and UV light. The posterior lateral eyes (PLEs) are wide-angle motion detectors that sense motions from the side and behind. Combined with the other eyes, PLEs give the spider a near 360° view of the world. The anterior lateral eyes (ALEs) have the best visual acuity of the secondary eyes. They are able to distinguish some details, as well, and without them, no “looming response” can be triggered by motion. Even with all the other pairs covered, jumping spiders in a study could still detect, stalk, and attack flies, using their ALEs only, which are also sufficiently widely spaced to provide stereoscopic vision. The anterior median eyes have very good vision. This pair of eyes is built like a telescopic tube with a corneal lens in the front and a second lens in the back that focus images onto a four-layered retina, a narrow, boomerang-shaped strip oriented vertically. Physiological experiments have shown they may have up to four different kinds of receptor cells, with different absorption spectra, giving them the possibility of tetrachromatic color vision, with sensitivity extending into the ultraviolet (UV) range. As the eyes are too close together to allow depth perception, and the animals do not make use of motion parallax, they have instead evolved a method called image defocus. Of the four photoreceptor layers in the retina, the two closest to the surface contain a UV-sensitive opsin (visual pigment), while the two deepest contain a green-sensitive opsin. The incoming green light is only focused on the deepest layer, while the other one receives defocused or fuzzy images. By measuring the amount of defocus from the fuzzy layer, calculating the distance to the objects in front of them is possible. In addition to receptor cells, red filters also have been detected, located in front of the cells that normally register green light. All salticids, regardless of whether they have two, three, or four kinds of color receptors, seemingly are highly sensitive to UV light. Some species (such as Cosmophasis umbratica) are highly dimorphic in the UV spectrum, suggesting a role in sexual signaling. Color discrimination has been demonstrated in behavioral experiments. The anterior median eyes have high resolution (11 min visual angle), but the field of vision is narrow, from 2 to 5°. The central region of the retina, where acuity is highest, is no more than six or seven receptor rows wide. However, the eye can scan objects off the direct axis of vision. As the lens is attached to the carapace, the eye’s scanning movements are restricted to its retina through a complicated pattern of translations and rotations. This dynamic adjustment is a means of compensation for the narrowness of the static field of vision. Movement of the retina in jumping spiders is analogous to the way many vertebrates, such as primates, move their entire eyes to focus images of interest onto their fovea centralis. In jumping spiders with a translucent carapace, such movements within the jumping spider’s eyes are visible from outside when the attention of the spider is directed to various targets.
Diet#
Although jumping spiders are generally carnivorous, many species have been known to include nectar in their diets, and one species, Bagheera kiplingi, feeds primarily on plant matter. None are known to feed on seeds or fruit. Extrafloral nectaries on plants, such as Chamaecrista fasciculata (partridge pea), provide jumping spiders with nectar; the plant benefits accordingly when the spiders prey on whatever pests they find. The female of the Southeast Asian species Toxeus magnus feeds its offspring with a milky, nutritious fluid for the first 40 days of their lives.
Taxonomy#
The monophyly of the family Salticidae is well established through both phylogenetic and morphological analyses. The sister group to Salticidae is the family Philodromidae. Synapomorphies of the two families include loss of cylindrical gland spigots and loss of tapeta in the indirect eyes. A 2015 revision of the Salticidae family divided it into seven subfamilies:
Onomastinae Maddison, 2015 – 1 extant genus Asemoneinae Maddison, 2015 – 4 extant genera (Hindumanes, originally placed here, was moved to Lyssomaninae) Lyssomaninae Blackwall, 1877 – 4 extant genera (including Hindumanes) Spartaeinae Wanless, 1984 – 29 extant genera in 3 tribes Eupoinae Maddison, 2015 – 3 extant genera Hisponinae Simon, 1901 – 6 extant genera Salticinae Blackwall, 1841 – about 540 extant genera in 27 tribes The Salticinae subfamily is the most diverse, comprising over 90% of the known species of jumping spiders.
Habitat#
Jumping spiders live in a variety of habitats. Tropical forests harbor the most species, but they are also found in temperate forests, scrubland, deserts, intertidal zones, and mountainous regions. Euophrys omnisuperstes is the species reported to have been collected at the highest elevation, on the slopes of Mount Everest.
Models for mimicry#
Some small insects are thought to have evolved an appearance or behavioural traits that resemble those of jumping spiders and this is suspected to prevent their predation, specifically from jumping spiders. Some examples appear to be provided by patterns on the wings of some tephritid flies, the nymph of a fulgorid and possibly some moths.
Fossils#
Very few jumping spider fossils have been found. Of those known, all are from Cenozoic era amber. The oldest fossils are from Baltic amber dating to the Eocene epoch, specifically, 54 to 42 million years ago. Other fossil jumping spiders have been preserved within Chiapas amber and Dominican amber.
See also#
Peckhamia (journal) Spider taxonomy
External links#
Asian jumping spiders and photo references Comprehensive resource on the morphology and taxonomy of jumping spiders (Salticidae): www.jumping-spiders.com Global Species Database of Salticidae Video of a jumping spider’s mating behavior High-Speed Photography of Jumping Spiders in Mid-air PBS Be Smart Video About Jumping Spider Vision Close-Up Video of Transparent Jumping Spider Captures Its Tube-Like Eyes Moving World Spider Catalog Jumping Spiders of NW-Europe Jumping spiders of Australia American Jumping Spiders – 70 Species Videos (includes introduction to salticids, predation, mating, and other behaviors) Movies of Habronattus courtship behavior The Australian Faunal Directory taxonomic classification of Australian salticids
Jumping spiders are unique due to their distinctive eye patterns and cephalothorax shape. Their front legs are larger than their hind legs, aiding in grasping prey and species recognition signaling. These spiders have eight eyes, with the front row of four being the most prominent and adapted for detailed, three-dimensional vision. They use their silk for safety lines while jumping and build shelters for molting, storing eggs, and sleeping. Jumping spiders have excellent vision, with their anterior median eyes having high resolution and the ability to detect color and UV light.
Ancestry Graph
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