Short‐ and long‐term resistance to desiccation in a minute litter‐dwelling land snail Lauria cylindracea (Pulmonata: Pupillidae)

Abstract

This study examines the water economy and resistance to desiccation in a minute (5 mg snail mass; 3 mm shell height) litter-dwelling land snail Lauria cylindracea (Pupillidae). As expected from its small size and from its moist habitat, L. cylindracea exposed to normothermic desiccation lost water at the highest rate revealed so far in our studies of resistance to desiccation in some 30 Israeli species and populations of land snailsÐ22.7% of the whole snail mass within 5 days. This high water loss was selectively contributed by the extra-pallial (free) compartment while soft body water content was closely maintained, without catabolism of body tissue as a source of metabolic water. Surprisingly, however, samples of L. cylindracea survived long periods (2±4 months) of aestivation when left undisturbed in the laboratory, sustaining a mass loss of 25±40%. This long-term aestivation revealed a different pattern of water compartmentalization, as the snails also lost water from the soft body tissue. Samples of these snails were rehydrated for 48 h and then exposed to an identical desiccation regime as the original, ®eld-collected snails. Most of the water taken up during rehydration was lost within the ®rst 24 h of desiccation, after which the rate of water loss dropped sharply. We conclude that short-term water regulatory responses to experimental desiccation differ from long-term responses to aestivation. We suggest that during long-term aestivation, a new set-point of water economy is established, in association with a metabolic depression, and that an extended period of contact with moisture is needed to change this set-point.

How do roads affect the habitat use of an assemblage of scavenging raptors?

“…This might be due to the fact that these birds perch and wait near roads in order to have the opportunity of feeding from road-killed animals (Donázar et al 1993;Dean and Milton 2003), and because they must eat quickly before bigger species arrive (Wallace and Temple 1987;Travaini et al 1998). Carcasses situated near roads were detected much faster Fitting curve of the best model (with lower AICc) is marked with a thicker line than those far from roads.…”

“…We worked during two seasons in 2006: autumn (May to June) and spring (October to December). Road-killed hares are commonly observed along roads (Donázar et al 1993;Travaini et al 1998), and legal and illegal hunting of deer and hares has increased in recent years. Our study sites were located near two roads surrounded mostly by rural areas with large farms dedicated to extensive sheep or cattle raising.…”

“…However, this area has one of the larger known populations of Andean condors within its distribution . We classified the six species in relation to their tolerance to human presence based on regional and local literature on the raptors' behavior and distribution (Donázar et al 1993;del Hoyo et al 1994;Travaini et al 1998;Bellati 2000;Ferguson-Lees and Christie 2001;Yorio and Giaccardi 2002;Lambertucci 2007). We classified the six species in relation to their tolerance to human presence based on regional and local literature on the raptors' behavior and distribution (Donázar et al 1993;del Hoyo et al 1994;Travaini et al 1998;Bellati 2000;Ferguson-Lees and Christie 2001;Yorio and Giaccardi 2002;Lambertucci 2007).…”

Heart rate and body weight alterations in juvenile specimens of the tropical land snail Megalobulimus sanctipauli during dormancy

“…Nevertheless, during this period the snail, which is in the starved state, spends part of its endogenous fuel reserves (22,23) and loses some water (14,(24)(25)(26), with a consequent decrease in body weight. In several gastropods heart rate was found to vary with nutritional state (27,28) and with hydration state (29,30).…”