Colorado Insects of Interest
Order: Araneae (Spiders)
Family: Salticidae (Jumping spiders)
Identification and Descriptive Features: Most jumping spiders that are noticed are small to moderate size (ca 4-12 mm) somewhat fuzzy looking spiders. The cephalothorax (area containing head and legs) is longer than wide but the abdomen can vary from a rounded shape to being quite elongate.
However, not all jumping spiders have gaudy markings. Some species blend well with bark or grass backgrounds while others are mimics of beetles or ants.
Distribution in Colorado: At least 45 species of jumping spiders are present in Colorado (Table 1) and representatives occur throughout the state. Some of the common species often enter homes, including the ubiquitous species Phidippus audax (bold jumper), Sitticus fasciger, Salticus scenicus (zebra jumper), and Platycryptus species.
Life History and Habits: Jumping spiders hunt as stalkers. Their smaller eyes along the side of the head detect movement, causing the spider to turn the very large anterior median eyes towards the object of interest. Possessing the best vision of any spiders, and possibly the best vision of any arthropod, they’re able to detect shapes, color, and depth of field. Some species can also detect ultraviolet, useful in recognition of mates or rivals.
Jumping spiders will slowly approach their prey, then rapidly jump to subdue and capture it. (This prey capture habit is often likened to the pouncing of a cat.) The jump may cover a distance several times their body length. Jumping spiders do not have unusually enlarged and muscular legs as is found in jumping insects - instead, their movement is achieved by rapid changes in hydraulic pressure of the blood. Muscular contractions force fluids into the hind legs, which cause them to extend extremely quickly.
Unlike most spiders, many jumping spiders will remain in place and turn towards a human or some other potential threat when it is detected. They may even approach it rather than flee for cover, an unusually curious type of behavior among spiders. However, jumping spiders are not aggressive and attempt to bite only if confined. The jaws of most species are too small to pierce the skin, but if successful, a jumping spider bite produces only mild and temporary pain with no complications. (However, all spider bites that do draw blood should be disinfected to avoid secondary infections by bacteria.)
A one-year life cycle is typical of jumping spiders. The most common species spend the winter as a nearly full-grown but still immature stage; some other species mature in fall. During the cold months they are usually found in a silken retreat that they construct in sheltered sites. The spiders mature in spring; males usually mature a couple of weeks before females.
In species that regularly mature before winter, mating occurs in fall and the females survive until the next spring. Males of these species die in fall. Other jumping spiders have life cycles that are indistinct and all life stages of these are found throughout the year.
Elaborate courtship rituals occur among the jumping spiders and the bright markings of the males may be central in these ritualized behaviors. After mating and maturation of eggs, the female constructs a silken retreat where she will produce an egg sac. She remains with the eggs until the spiderlings hatch and disperse. After they have left she may produce additional egg sacs during the summer.
In addition to crawling, the tiny spiderlings engage in long distance dispersal by ballooning. This is achieved by producing a silken line to catch winds that carry the spiders. When crawling and hunting jumping spiders also use silk to produce a dragline that is periodically attached to a solid surface. This allows them to recover if they fall.
|Some Phidippus species of jumping spiders present in Colorado.|
|Table 1. A Checklist of jumping spiders known from Colorado. Primary source: Denver Museum of Nature and Science Spider Survey Database, accessed October 24, 2008|
|Eris militaris||Eris rufus|
|Habronattus americanus||Habronattus brunneus|
|Habronattus clypeatus||Habronattus cockerelli|
|Habronattus cognatus||Habronattus conjunctus|
|Habronattus cuspidatus||Habronattus festus|
|Habronattus hirsutus||Habronattus venatoris|
|Metacyrba arizonensis||Metaphidippus sp.|
|Pelegrina aeneola||Pelegrina flavipes|
|Pelegrina furcata||Pelegrina galathea|
|Pelegrina montana||Pelegrina peckhamorum|
|Pelegrina proterva||Pelegrina verecunda|
|Pellenes sp.||Phanias monticola|
|Phiddipus apacheanus (Apache jumping spider)||Phiddipus asotus|
|Phidippus audax*(bold jumper)||Phidippus cardinalis (cardinal jumper)|
|Phidippus clarus||Phidippus johnsoni (Johnson jumper)|
|Platycryptus californicus*||Platycryptus undatus|
|Pseudicius siticulosus||Salticus scenicus* (zebra jumper)|
|Sassacus papenhoei||Sassacus vitis|
|Sitticus fasciger*||Sitticus finschi|
|Synageles occidentalis||Talavera minuta|
|Thiodina sp.||Tutelina sp.|
|* Species of jumping spiders that are most commonly found in homes|
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