Department of Genetics and Biometry, University College London, Wolfson House, 4 Stephenson Way, London NW1 2HE, U.K.
Microhabitat choice and high temperature tolerance in the land snail Theba pisana (Mollusca: Gastropoda)
Article first published online: 20 AUG 2009
1985 The Zoological Society of London
Journal of Zoology
Volume 207, Issue 2, pages 201–211, October 1985
How to Cite
Cowie, R. H. (1985), Microhabitat choice and high temperature tolerance in the land snail Theba pisana (Mollusca: Gastropoda). Journal of Zoology, 207: 201–211. doi: 10.1111/j.1469-7998.1985.tb04924.x
- Issue published online: 20 AUG 2009
- Article first published online: 20 AUG 2009
- (Accepted 31 January 1985)
Adults of the land snail Theba pisana near the species’northern limit (Tenby. South Wales) spend the daytime inactive attached to stems of tall vegetation, avoiding higher temperatures near the ground, while juveniles remain low down. This may be related to the lesser ability of juveniles to withstand desiccation for long periods, and/or to their requiremcnts for an easily accessible source of suitable food during growth. In the field and laboratory, adults (at least) respond to light and wind direction, avoiding the hottest and most exposed sides of stems on which they rest.
The upper lethal temperature of snails from S. Wales lies between 42 and 46 °C, depending on exposure time. Juveniles are more tolerant than adults, probably because of their greater ability to use evaporative cooling for short periods. Spanish T. pisana are more tolerant (upper lethal limit 46–50 °C) than Tenhy snails; this difference may have a genetic basis. Aestivating Spanish snails are more tolerant than active ones.
Climbing and orientation are essential for both adults and juvenilcs in the Mediterranean habitats where Theba pisana evolved, since ground temperatures can exceed the lethal limit. It is less important at the northern edge of the range, but is still retained by the adults.