The function of trail following in the pulmonate slug, Limax pseudoflavus

doi:10.1016/S0003-3472(05)80204-0

Animal Behaviour

Volume 43, Issue 5, May 1992, Pages 813-821

https://doi.org/10.1016/S0003-3472(05)80204-0 Get rights and content

Abstract

Trail following in Limax pseudoflavus Evans is easily observable under laboratory conditions but it is less frequent in the field and its function remains unclear. In experiments allowing the choice between trails and other environmental cues slugs tended to follow trails most frequently when those trails were going in a direction close to that dictated by the other cue. Similarly trails were more often followed when approached at a narrow angle. Trail following was observed as a prelude to courtship. It is concluded that trails provide low priority directional cues and that they are only followed in the absence of other cues or when their direction closely coincides with those other cues. Trail following is a component of food finding, homing and courtship behaviour in the field, but in each case its role may be subordinate to that of airborne odours. Measurements of the quantity of mucus in the trails show that there is no reduction in the secretion of mucus while trail following. Trail following cannot therefore be seen as a mucus-saving tactic.

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Cited by (26)

A predatory snail distinguishes between conspecific and heterospecific snails and trails based on chemical cues in slime
2005, Animal Behaviour
Citation Excerpt :
A snail following the trail would then only have to line up its right lip tentacle on the side of the trail with the highest concentration of the pheromone in order to be moving along the trail in the same direction in which the trail was laid. Directional following of conspecific trails has been reported for many gastropod mollusc species including land snails, pond snails, land and marine slugs, the marsh periwinkle and limpets (Wells 1965; Cook 1969, 1979, 1992; Cook et al. 1969; Wells & Buckley 1972; Bretz & Dimock 1983; Wareing 1986). In contrast, in reports of following of heterospecific mucus trails by snails and slugs, a lack of direction-specific following seems to be the rule (Gonor 1965; Pearce & Gaertner 1996; Clifford et al. 2003).
The rosy wolfsnail, Euglandina rosea, is a predatory snail native to the southeastern United States. It eats other snails and slugs, tracking them by following their mucus trails. Although wolfsnails follow mucus trails of both prey and conspecifics, they rarely eat conspecifics, and only conspecific trails are followed directionally. We investigated how wolfsnails distinguish conspecifics from prey snails (Helix aspersa) and how they determine directionality of conspecific mucus trails. We found that wolfsnails used chemical cues present in mucus to distinguish conspecifics from prey, and were less likely to attack a snail covered with wolfsnail mucus than one covered with prey mucus (experiment 1). Juvenile wolfsnails that were isolated from conspecifics before hatching recognized conspecifics as nonprey (experiment 2), and adult wolfsnails learned to follow trails of novel substances associated with exposure to other wolfsnails (experiment 3). Wolfsnails were equally attracted to both soluble and insoluble components of conspecific mucus (experiment 4) and followed conspecific mucus trails directionality even after the trails had been washed (experiment 5). We also examined whether a structural or chemical asymmetry in conspecific mucus allowed wolfsnails to determine directionality of conspecific trails. Although results of scanning electron microscopy provided no support for directionality using a structural asymmetry, manipulations of wolfsnail trails (experiments 6, 7) indicated that wolfsnails use a right/left chemical asymmetry in mucus trails to orient themselves on conspecific trails in the same direction as the trail-layer snail, independent of the trail layer's direction of movement.
A design for multifactorial choice experiments: An example using microhabitat selection by sea slugs Onchidoris bilamellata (L.)
2004, Journal of Experimental Marine Biology and Ecology
When animals make choices (selecting foods, habitats, mates, etc.), they must assess multiple factors, often simultaneously. Moreover, certain factors have more weight in the choice-making process than others. Typically, however, studies of animal choice consider the effect of only one factor (i.e. different levels of a single factor). In this paper, we present a design for multifactorial choice experiments, in which animals are offered a choice between different levels of two or more factors. The advantages of the multifactorial choice design are that interactions between different factors affecting choice can be explicitly examined and the relative importance of several factors can be assessed. We illustrate the use of the design in a laboratory experiment to examine the effect of light intensity and texture of substratum on selection of microhabitat by sea slugs (Onchidoris bilamellata (L.)). In this experiment, sea slugs preferred darkness over light, irrespective of the texture. They also preferred rough substratum over smooth substratum, but only when they were in the dark. In light, sea slugs did not show a preference between textures. Thus, the analysis showed: (1) preferences for different levels of one factor (light intensity) overrode preferences for different levels of the other factor, and (2) there was a significant interaction between factors (such that preferences for texture depended on light intensity).
Mucus from marine molluscs
1998, Advances in Marine Biology
Mucus functions in many invertebrate physiological processes and also influences structuring of the community and the ecosystem. Molluscan mucus is mostly water. The remaining components are protein, carbohydrate and lipid. The detailed structure of the protein–polysaccharide acidic glycosaminoglycan component is not yet known. Mucus is probably released in dehydrated form in distinct, membrane-bound packages, which then absorb water. A functioning mucus is probably formed by mixing of mucins from different types of gland. Under small deformities, hydrated mucus is a viscoelastic solid, able to function as a rope. As stress increases, it yields to become a liquid which can return to the solid state once the stress is released. It is these properties that allow locomotion by molluscs on what is seemingly an adhesive. On dehydration, the strength and stiffness of mucus increase such that molluscs can suspend their body by a thread of it. Mucus production has been studied quantitatively by various methods, some gravimetric and some colorimentric using pedal, faecal, pseudofaecal and hypobranchial mucus: there is much spatial and temporal variation.
In locomotion mucus is a coupling agent between foot and substratum; a medium in which propulsive cilia beat; and a drogue. Mucus deposited as a trail by gastropods is an important facet of their environment. Many species follow mucus trails possibly contributing to the observed patchy distributions of gastropods. The methods by which the presence and polarity of mucus trails are detected is poorly understood.
Mucus plays a vital role in feeding. In filter-feeding bivalves, mucus aids the transport of food from gill to mouth and is employed to cleanse the mantle cavity of particles rejected by the labial palps. In gastropods mucus nets and bags are used to trap food prior to ingestion and some groups roll their prey in mucus to prevent its escape. Pedal mucus may be ingested after it has become studded with organic material and perhaps act as a fertilizer for microbial growth.
A copious secretion of epithelial mucus is used to isolate molluscs from their environment and mucus may also serve as an ionoregulator. Mucus may also contain specific products to render the animal poisonous, distasteful or irritating. Agglutinin and lysozyme have been found in mucus from marine molluscs. Mucus secretion can present a considerable drain of energy (up to 70% of consumed energy). The fate of molluscan mucus is largely unknown and probably makes a considerable contribution to POM in inshore waters, although its is readily degradable by marine microbes. Given the persistence of mucus, densities of benthic gastropods and their motility patterns, much of the gastropod-inhabited benthos is likely to be covered for most of the time with a layer of pedal mucus.
Gender choice and gender conflict in a non-reciprocally mating simultaneous hermaphrodite, the freshwater snail, Physa
1996, Animal Behaviour
Like freshwater pulmonate snails in general, maturePhysa heterostropha pomilia(Say) are hermaphroditic but cannot reciprocally inseminate each other simultaneously. One member of a pair assumes the male role and the other the female, after which swapping may occur. The tendency for a pair of prospective copulants to elect the same sexual role was defined as gender conflict, and distinguished from sexual conflict, the more widely noted tendency for females to reject low-quality males. Experiments assessed whether previous reproductive history affected the likelihood of mating and the sexual role assumed and evaluated the strength of gender and sexual conflicts. Snails were selected from isofemale lines fixed for albinism at two complementary loci. Ten pairings were made involving all combinations of four categories of reproductive history: previously selfing virgin, not previously selfing virgin, previously selfing mated, and not previously selfing mated. Encounter times, evasive behaviours, and polarity of mating were recorded. Results suggested that the probability of initiating copulation as male in any encounter increased with autosperm store, and that snails mounted as female may decrease the overall probability of mating by rejective behaviour when their reserves of allosperm are high. There was no evidence that snails ever use any mechanism to increase their likelihood of being mounted as female. Evasive behaviours observed in encounters between virgin snails were best attributed to male–male gender conflict, but such behaviour patterns seemed to derive from sexual conflict when virgin snails encountered previously mated snails. Male–male gender conflict did not, however, detectably lengthen contact times, lead to bouts of sperm trading or ultimately lower mating success.
Messages in the mucus: Selection of land snail resting sites based on the presence of mucus from conspecifics and other species
2023, Invertebrate Biology
Transmission of parasitic mites (Riccardoella oudemansi) between limacid slug hosts: the role of parasite and host behaviour
2023, Symbiosis

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Animal Behaviour

Abstract

References (29)

Responses to conspecific chemical stimuli in the terrestrial snail Achatina fulica (Pulmonata: Sigmurethra)

Behav. Biol.

Mucus trail following by the slug Limax grossui Lupu

Anim. Behav.

Homing by the slug Limax pseudoflavus

Anim. Behav.

Huddling and the control of water loss by the slug Limax pseudoflavus Evans

Anim. Behav.

A study of the homing habit of the limpet

Anim. Behav.

Snails and Trails

Anim. Behav.

Between and within population differences in geotactic responses in the land snail Arianta arbustorum L.) (Helicidae)

Behaviour

Daily cycles of feeding and locomotion in Helix aspersa

Haliotis

The aerial mating of the great slug

Discovery

Relative importance of airborne odours and trails in group homing of Limacus flavus (Linnaeus) (Gastropoda, Pulmonata)

J. moll. Stud.

The use of mucous trails by intertidal limpets to enhance food resources

Biol. Bull. mar. biol. lab. Woods Hole

Field studies of homing in the pulmonate slug Limax pseudoflavus Evans

J. moll. Stud.

Functional aspects of trail following in the carnivorous snail, Euglandina rosea Ferussac

Malacologia

The mucus producing glands and the distribution of cilia of the pulmonate slug Limax pseudoflavus

J. Zool., Lond.

Cited by (26)

A predatory snail distinguishes between conspecific and heterospecific snails and trails based on chemical cues in slime

A design for multifactorial choice experiments: An example using microhabitat selection by sea slugs Onchidoris bilamellata (L.)

Mucus from marine molluscs

Gender choice and gender conflict in a non-reciprocally mating simultaneous hermaphrodite, the freshwater snail, Physa

Messages in the mucus: Selection of land snail resting sites based on the presence of mucus from conspecifics and other species

Transmission of parasitic mites (Riccardoella oudemansi) between limacid slug hosts: the role of parasite and host behaviour