Wolf Spiders: Trochosa terricola
Although they do not hunt in packs like wolves, the spiders of the family Lycosidae are very much nocturnal predators. These wolves, unlike their counterparts, are readily found in the UK and within the genus Trochosa 4 species are present in Europe (Roberts, 1995). These are large spiders (comparative to other British species) with a heavyset body reaching sizes of 20mm, although many rarely exceed 10mm.
T. terricola is a common species that can be found prowling damper environments amongst moss and stones all year round. It has light brown colouration on the legs and fringes of the carapace with a cardiac mark behind the eyes of the same tawny brown. The abdomen is chestnut brown and the legs exhibit flecks of tan.
Wolf spiders generally sit and wait for prey to come to them, reacting to the vibrations produced by the smallest movements. Their eyes offer visual sensitivity and spatial awareness which is unparalleled in spiders (bar the jumping spiders) but only produce sharp images up close (Herberstein, 2011). This is a possible reason for the elaborate courtship displays found in Lycosid spiders, a kind of spider semaphore (Foelix, 1996).
Finding them at night may at first present a challenge but with a torch handy they soon become apparent. Night time is when wolf spiders truly shine, literally. Their eyes, not unlike cats eyes, reflect light. The reflective membrane that allows this, known as the tapetum, has a grid iron structure whereby beneath each row of receptors in the eye there lies a row of reflectors. The tapetum is mainly formed from layers of guanine crystals which usually cause the light reflected to be green (Land, 2000).
During the day these predators will hide away in dugout burrows lined with silk, a more primitive arrangement to building a web. The mothers make doting parents and will carry their egg sacs and spiderlings between burrows to keep them safe as well as making sure there is good foraging to be had once the spiderlings disperse. This takes place about a week after hatching (Foelix, 1996).
T. terricola was first recorded in Britain in 1820 and since then a large database of sightings has been established as part of the Spider and Harvestman Recording Scheme. Over 10,000 records have been made and many of these occur in the South and East of the UK where the warmer conditions allow spiders to be active for more of the time (Partridge, 2013). Further information on the distribution of this species can be found here.
- Foelix, R.F. (1996) Biology of spiders. 2nd edition, Oxford University Press.
- Herberstein, M. E. (Ed.). (2011) Spider behaviour: flexibility and versatility. Cambridge University Press.
- Land, M. F. (2000) Eyes with mirror optics. Journal of Optics A: Pure and Applied Optics, 2(6), 44-50.
- Partridge, W. J. (2013) Spider and Harvestman Recording Scheme Website: the national recording scheme for spiders and harvestman in Britain. Summary for Trochosa terricola (Araneae).
- Roberts, M.J. (1995) Colins Field Guide: Spiders of Britain & Northern Europe. HarperCollinsPublishers.