Rare Species Guide

  Basis for Listing

Marpissa formosa (Beautiful Jumper) is known from sites on the East Coast and Gulf Coast as well as from Great Lakes states. There are only seven known occurrences of Beautiful Jumper in Minnesota (two of these records are photographic) in seven counties. Beautiful Jumper was listed as special concern in 2013.

  Description

Jumping spiders are one of the most recognizable spiders as they generally have a stout body, rather short legs, a very large set of eyes, and the ability to jump. Their body shapes and colors often imitate prey such as ants and beetles. Beautiful Jumper is one of four species in the genus Marpissa found in Minnesota. Compared with other jumping spiders, which are commonly stocky in appearance, Beautiful Jumper has an elongate body and long front legs; males have a shiny black head and body, both marked with white spots; the female is brown with a central white stripe on the abdomen that is usually bordered by wide reddish-brown bands. Viewed from the side, the shape of the head (carapace) is flatter than that of other jumping spiders. Males have an overall length of 6-7 mm (0.24-0.28 in.) and females 7-9 mm (0.28-0.35 in.).

  Habitat

In Minnesota, this species has been found as far north as Cass County and as far south as Blue Earth County. Records are from upland prairie, lowland prairie, wet meadow/carr, and marsh communities. In Douglas County, a male was taken from big bluestem (Andropogon gerardi) at Lake Carlos State Park and in Sherburne County, a female specimen was collected at Uncas Dunes Scientific and Natural Area from mixed prairie/meadow including goldenrod (Solidago spp.), cattail (Typha spp.), grasses (Gramineae), and horsemint (Monarda spp.). Barnes (1958) associates this species with shrubs and herbaceous vegetation.

  Biology / Life History

Very little is known about the specific details of the biology and life history of this species, but it shares a number of general traits with other species in the group.

Jumping spiders do not spin webs for catching prey. Instead, they construct small tent-like silken retreats under rocks or logs or on plants, which they use at night and during hibernation. The females also lay their eggs in them. Jumping spiders are most active during the day, and they prefer sunshine. They tend to stay in their retreats on cloudy or rainy days. Jumping spiders are generally interested in whatever approaches them and will often turn and face human observers and may even advance towards them. They are generally harmless to people.

Jumping spiders have four pairs of eyes with the large principal pair giving them better vision than other spiders. The forward-looking placement of this pair of eyes provides binocular vision enabling them to judge distances accurately, and they are able to identify prey, predators, and mates from up to 30 cm (1 ft.) away (Weber 2002). Physiological and behavioral experiments have demonstrated that they have color vision, possibly extending into the ultraviolet range.

Jumping spiders feed primarily on insects, though some may feed on web-building spiders. They will also feed on other jumping spiders, usually those that are smaller than themselves. Jumping spiders actively stalk their prey instead of snaring it in a web. They may, however, steal insects snared by the webs of other spiders. Jumping spiders hunt primarily during the day, using their keen eyesight to locate prey. Having spotted a potential quarry, a jumping spider will slowly stalk the prey until it is within jumping distance. Then it lifts its front legs and pounces. Like all spiders, jumping spiders move their legs not by muscular contractions but by changing the pressure of the fluid within them. This hydraulic system enables them to jump up to several times their body length without having large muscular legs. Before jumping, the spider always affixes a silk safety line to whatever it is jumping from; in case it falls, it can climb back up this tether.

The same visual capabilities that are critical to jumping spiders’ success as hunters also support complex courtship behaviors. Males often differ in appearance from females and can have colorful, sometimes iridescent, modifications to their bodies, front legs, or mouthparts. The parts of the male's body that are used in courtship are often conspicuously colored. In many jumping spider species, the males perform courtship dances in front of the females that are species specific. The male's movements range from a slight lifting of a leg to complex movements such as bobbing their bodies, twitching their abdomen, performing zig-zag movements, waving their front legs, or flashing their mouthparts into the eyes of the females. Some male jumping spiders also have auditory signals that, when amplified, sound like buzzes or drum rolls. It is presumed that females choose mates based on their courtship dances. After mating, females lay their eggs in their silken retreat and often guard their eggs and newly hatched young.

  Conservation / Management

With only seven records confirmed over the past 40 years, there is not yet enough information to guide specific management plans.

  Conservation Efforts in Minnesota

Surveys are ongoing to determine the distribution of this species in Minnesota.

  References and Additional Information

Barnes, R. D. 1958. North American jumping spiders of the subfamily Marpissinae (Araneae, Salticidae). American Museum Novitates 1867:1-50.

Ehmann, W. J. 2002. Conservation biology of special concern jumping spiders (Araneae: Salticidae) of Minnesota. Final Report submitted to the Natural Heritage and Nongame Research Program, Minnesota Department of Natural Resources. 11 pp.

Ehmann, W. J., and B. E. Boyd. 1997. Surveys for proposed special concern jumping spiders of Minnesota. Final report submitted to the Minnesota Department of Natural Resources. 18pp.

Forster, L. M., and M. R. Forster. 1999. How do jumping spiders catch up on their prey?: a model for pursuit behaviour. (Araneae; Salticidae). Preliminary Draft, 06 Aug 1999.

Maddison, W. 1994. Jumping spiders of America north of Mexico [web application]. Tree of Life web project, University of British Columbia, Vancouver, Canada. <http://tolweb.org/accessory/Jump>. Accessed 16 Aug 2006.

Richman, D. B., and B. Cutler. 1978. A list of the jumping spiders (Araneae: Salticidae) of the United States and Canada. Peckhamia 1(5):82-110.

Weber, L. 2002. Spiders of the North Woods (North Woods naturalist guides). Kollath-Stensaas Publishing, Duluth, Minnesota. 216 pp.