Jumping spider
Jumping spiders belong to the family Salticidae. These spiders catch their prey by jumping on them.
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| An adult male Phidippus audax jumping spider | |
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| Family: | Salticidae Blackwall, 1842
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Species live in many habitats, from leaves lying on the ground, to the tops of trees in the forest, and even way up on Mt. Everest.[1] They are found on every continent in the world except for Antarctica.
At present, 5026 species in 530 genera have been found.[2] They are actually the largest family of spiders, with about 13% of all species.[3]
Appearance
They are easy to identify because their eye pattern is distinctive. They have eight eyes, two of which are very large, and because their faces form a flat surface, facing where they are going.
Behaviour
They often hunt high up in bushes, or on vertical walls. To save themselves from falling they do something very much like what climbers do to protect themselves in the mountains. Humans tie a rope to the mountain and attach the other end to the harness they wear. Jumping spiders attach silk from their spinnerets to the thing on which they are standing and then they jump. While they are moving through the air they make silk so that there is always a safety rope trailing out behind them.
Jumping spiders can jump long distances for their size, as much as 16 cm.[4]p11 When they jump, they use their hind legs. They raise their front legs to be ready to grab their prey.[5]
Many other kinds of spider hunt at night, but jumping spiders depend on their eyes, so they like to come out in the daytime. Often they will find a sunny spot on a wall or tree trunk.[4]
There are however many variations, and many surprising aspects. For one thing, Salticids do not necessarily follow a straight path in approaching prey. They may follow a circuitous course, sometimes even a course that takes the hunter through places where the prey is not visible. Such complex behaviour is hard to reconcile with an organism that has such a tiny brain. Some spiders in species of Portia can take long detours from one bush down to the ground, then up the stem of another bush to capture a prey item on a particular leaf. Such behaviour is the subject of research.[6]
Because they have good vision, jumping spiders can see human beings when they approach. Some jumping spiders may run away from approaching humans, and some do not. But either way a jumping spider will watch a nearby human being.[7] When they do not run away, but do turn to keep watch over a human being, it may seem that they are interested in us. Some of them will even jump from where they are sitting on branches, rocks, etc. onto a person's finger or camera. These spiders only bite to get something to eat or to defend themselves, so if they jump on somebody's hand they will not bite. People might get bitten if they pinch or squeeze a jumping spider.
Physical capabilities
Jumping spiders are able to climb glass and other very smooth surfaces because besides having two claws on each foot they also have sticky hairs (called scopulae) that hold onto the surface.[8] Many tiny ends on each hair are held to the glass by Van der Waals forces, the force that will make two very flat sheets of glass stick tightly together without any glue.[9]
Jumping spiders are able to see very clearly. Two of their eight eyes are very large and are complicated inside. The eyes cannot move, so the spider will often move its body to look at what it wants to see. However, it can also move the retinas of its two main eyes on the inside of the eye, so the center of the eye's picture can be moved.[10] So the jumping spider has binocular vision.[11]
Use of silk
Very few kinds of jumping spider make webs; instead they use their silk for their safety rope and also to make a kind of tent where they sleep at night, shed their skins (molt), lay their eggs, and enjoy a long sleep during winter (hibernate).[4] Their silk comes out of their spinnerets (see diagram).
Images
Phidippus audax preparing to jump
A camouflaged Menemerus, a jumping spider, with a winged male ant as prey. Camouflage is a form of crypsis, the ability of an organism to avoid observation or detection by other organisms.
One of the larger jumping spiders found in the eastern part of the U.S., Phidippus mystaceus. This female is 12 mm. in body length.
The squared-off head and eight eyes of a jumping spider
Jumping Spider Media
Plexippus petersi on a human finger
The visual fields of a jumping spider
The eight eyes of a Telamonia dimidiata located near the front
Unidentified salticid jumping with trailing dragline
Courtship display of Saitis barbipes jumping spider
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References
- ↑ Wanless F.R. (1975). "Spiders of the family Salticidae from the upper slopes of Everest and Makalu". Bulletin of the British Arachnological Society. 3 (5): 132–136.
- ↑ Wayne P. Maddison; Melissa R. Bodner; Karen M. Needham (2006). "Salticid spider phylogeny revisited, with the discovery of a large Australasian clade (Araneae: Salticidae)" (PDF). Zootaxia. 1893: 49–64.
- ↑ Peng, Xian-Jin; I-Min Tso; Shu-Qiang Li (2002). "Five new and four newly recorded species of jumping spiders from Taiwan". Zoological Studies. 41 (1): 1–12. [1] Archived 2021-11-10 at the Wayback Machine
- ↑ 4.0 4.1 4.2 Foelix, Rainer F. (1996). Biology of Spiders'. Oxford University Press. ISBN 0-674-07431-9.
- ↑ Kaston B.J. 1953. How to know the spiders. Dubuque, Iowa. p240
- ↑ Richman D.B. & Jackson, R.R. 1992. A review of the ethology of jumping spiders (Araneae, Salticidae). Bulletin of the British Arachnological Society. 9, 33-37.
- ↑ Maddison, Wayne 1995. Salticidae. [2] Archived 2011-08-28 at the Wayback Machine
- ↑ Compton, John 1954. Life of the Spider. Mentor. p. 77
- ↑ Antonia B. Kesel, Andrew Martin, and Tobias Saidi. 2004. Getting a grip on spider attachment: an AFM approach to microstructure adhesion in arthropods. Smart Materials and Structures. 13, 512-518
- ↑ National Geographic video of capture of bee by jumping spider
- ↑ Madison, Wayne 1995. Jumping spider vision. [3] Archived 2015-09-07 at the Wayback Machine
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