Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Snakes”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources
PubMed1996

Diagnosis of subclinical cryptosporidiosis in captive snakes based on stomach lavage and cloacal sampling.

The applicability of stomach lavage and cloacal swab techniques for diagnosis of subclinical cryptosporidiosis were tested in eight captive snakes subclinically infected with Cryptosporidium serpentis. Two feeding regimes were employed. The snakes were first fed 7 days prior to stomach and cloaca sampling, and then 3 days prior to sampling, and the oocysts were detected by fluorescein labeled monoclonal antibody (mAb) and by acid-fast stained (AFS) direct wet smear (DWS). The overall sensitivity of AFS DWS was 95% for stomach samples and 57% for cloacal samples, with false-negativity of 5% and 43%, respectively. A significant relationship (P < 0.01) was found between stomach and cloacal samples when mAb were used for oocyst detection. Stomach sampling was diagnostically superior to cloacal sampling for identifying snake subclinical cryptosporidiosis. Based on gastric aspirates, cryptosporidial infection was diagnosed in all eight animals, and only in two or four snakes when cloacal swab material was processed by AFS or by mAb, respectively. Feeding snakes 3 days prior to sampling facilitated diagnosis based on stomach samples; however, it did not improve diagnosis when cloacal samples were used. The fraction of oocyst-positive stomach samples was significantly higher (P < 0.05) for snakes fed 3 days prior to gastric lavage when compared with the fraction of positive samples of snakes fed 7 days prior to lavage. If subclinical cryptosporidiosis is suspected in a non-eating snake patient, force-feeding and stomach lavage, 3 days after the meal, is recommended.

Animals↗
PubMed2001

Snake inhibitors of phospholipase A(2) enzymes.

Phospholipase A(2) (PLA(2)) enzymes consist of a large family of proteins which share the same enzymatic function and display considerable sequence homology. These enzymes have been identified and characterised in mammalian tissue and snake venoms. Numerous physiological functions have been attributed to mammalian PLA(2)s and they are nontoxic. In comparison, venom PLA(2)s are toxic and induce a variety of pharmacological effects that are probably mediated via membrane receptors. Snake PLA(2) inhibitors (PLIalpha), with a similar structure to the M-type receptor, have been identified as soluble complexes in the serum of viperinae and crotalinae snakes. These inhibitors showed selective binding to crotalid group II PLA(2)s and appeared to be restricted to the serum of this snake family. Analysis of PLA(2) binding to recombinant fragments of PLIalpha indicated that the CRD region was most likely responsible for enzyme inhibition. A second type of inhibitor, PLIbeta, has been identified in serum from one viperid snake and consists of a leucine-rich structure. The third type of inhibitor, PLIgamma, was found in the serum of five snake families and contains a pattern of cysteine residues that define a three-finger structure. PLIgamma inhibitors isolated from the serum of Elapidae, Hydrophidae, Boidae and Colubridae families were able to inhibit a broad range of enzymes including the nontoxic mammalian group IB and IIA PLA(2)s, and bee venom group III PLA(2). However, differences in the binding affinities indicated specificity for particular PLA(2)s. A different representation has emerged for crotalid and viperid snakes. Their PLIgammas did not inhibit bee venom group III, mammalian group IB and IIA enzymes. Furthermore, inhibition data for the gamma-type inhibitor from Crotalus durissus terrificus (CICS) showed that this inhibitor was specific for viperid beta-neurotoxins and did not inhibit beta-neurotoxins from elapids [1]. Further studies are required to determine if this phenomenon is true for all gamma-type inhibitors from Crotalidae snakes. The relative distribution of these inhibitors, their specificities and the structural features involved in binding are discussed in this review.

Animals↗
PubMed2001

The accumulation and effects of environmental contaminants on snakes: a review.

In any ecological risk assessment, a full complement of the relevant members of the ecosystems being studied should be considered. Reptiles in general, and snakes in particular, are important although often neglected components of terrestrial and aquatic ecosystems and should be included in any study on environmental contamination. By neglecting reptiles, the risks posed by a particular contaminant cannot be fully assessed. Since all snakes are secondary, tertiary, and top predators, they are susceptible to the bioaccumulation of environmental contaminants. Their unique life histories make their roles in food webs diverse and important, and they are crucial to the proper functioning of many ecological processes. We review and summarize organic and inorganic contaminant and radionuclide/radiation residue and lethal and sublethal effects data for snakes to stress the importance of snakes and encourage their inclusion in ecological risk assessments, to demonstrate the paucity of available contaminant data on snakes and reveal the main information gaps, to encourage further ecotoxicological studies on snakes, and to facilitate the use of existing snake contaminant data in ecological risk assessments. This review is the most comprehensive review currently available on the effects on and accumulation of environmental contaminants in snakes.

Animals↗
PubMed1995

Role of appendages in skin resistance and iontophoretic peptide flux: human versus snake skin.

PURPOSE: 1. The assessment of the role of hair follicles and sweat glands in skin resistance and percutaneous iontophoretic flux of 9-desglycinamide, 8-arginine vasopressin (DGAVP) by comparing two skin species: human stratum corneum which contained hair follicles, sweat and sebaceous glands, and shed snake skin which lacked all appendages. 2. The effect of 1-dodecylazacycloheptan-2-one (dodecyl-Azone, a lipid perturbing agent) on the iontophoretic DGAVP flux. METHODS: Iontophoresis in vitro was performed in a transport cell (0.79 cm2 area available for percutaneous transport) by 8-hours application of a pulsed constant current of 100 Hz, 50% duty cycle and 0.26 mA.cm-2 current density delivered by a pair of Ag/AgCl electrodes, of which the anode was facing the anatomical surface of the skin samples. RESULTS: The initial resistances of human stratum corneum and shed snake skin samples were of the same order of magnitude (20-24 k omega.cm2) and both skin species showed a comparable resistance-decrease profile during 8-hours iontophoresis, indicating that the resistances were mainly determined by the stratum corneum and not greatly influenced by the appendageal structures. The initial resistances of the skin samples pretreated with dodecyl-azone were less than 50% of the values of untreated samples. Because dodecylazone is known to perturb the ordering of the intercellular lipids, the effect of azone on the resistance confirms that the resistance mainly resides within the intercellular lipids of the stratum corneum. No correlation was found between the iontophoretic DGAVP-flux and the conductance of human skin. For shed snake skin, however, a good correlation was found, indicating that the iontophoretic permeability of human skin in vitro for a peptide such as DGAVP is, unlike shed snake skin, not related to its overall permeability to ions. While the initial resistances of both human and snake skin were in the same order of magnitude and showed the same declining profile during iontophoresis, the steady state iontophoretic DGAVP flux across human stratum corneum was approximately 140 times larger than through shed snake skin. These findings suggest that small ions follow pathways common to both skin types, presumably the intercellular route, while the peptide on the other hand is transported differently: across snake skin presumably along intercellular pathways only, but across human stratum corneum along additional pathways (most likely of appendageal origin) as well. This interpretation is supported by the observations made of the effects of dodecyl-azone on DGAVP-iontophoresis. Pretreatment with dodecyl-azone did not significantly change steady state fluxes and lag times of DGAVP-iontophoresis across human stratum corneum, but resulted in a significant 3-fold lag time decrease and a 3-fold flux increase of DGAVP-iontophoresis across snake skin. CONCLUSIONS: The results of these in vitro studies emphasize the importance of the appendageal pathway for iontophoretic peptide transport across human stratum corneum.

Adult↗
PubMed2000

The Pleistocene serpent Wonambi and the early evolution of snakes.

The Madtsoiidae were medium sized to gigantic snakes with a fossil record extending from the mid-Cretaceous to the Pleistocene, and spanning Europe, Africa, Madagascar, South America and Australia. This widely distributed group survived for about 90 million years (70% of known ophidian history), and potentially provides important insights into the origin and early evolution of snakes. However, madtsoiids are known mostly from their vertebrae, and their skull morphology and phylogenetic affinities have been enigmatic. Here we report new Australian material of Wonambi, one of the last-surviving madtsoiids, that allows the first detailed assessment of madtsoiid cranial anatomy and relationships. Despite its recent age, which could have overlapped with human history in Australia, Wonambi is one of the most primitive snakes known--as basal as the Cretaceous forms Pachyrhachis and Dinilysia. None of these three primitive snake lineages shows features associated with burrowing, nor do any of the nearest lizard relatives of snakes (varanoids). These phylogenetic conclusions contradict the widely held 'subterranean' theory of snake origins, and instead imply that burrowing snakes (scolecophidians and anilioids) acquired their fossorial adaptations after the evolution of the snake body form and jaw apparatus in a large aquatic or (surface-active) terrestrial ancestor.

Animals↗
PubMed2006

A Cretaceous terrestrial snake with robust hindlimbs and a sacrum.

It has commonly been thought that snakes underwent progressive loss of their limbs by gradual diminution of their use. However, recent developmental and palaeontological discoveries suggest a more complex scenario of limb reduction, still poorly documented in the fossil record. Here we report a fossil snake with a sacrum supporting a pelvic girdle and robust, functional legs outside the ribcage. The new fossil, from the Upper Cretaceous period of Patagonia, fills an important gap in the evolutionary progression towards limblessness because other known fossil snakes with developed hindlimbs, the marine Haasiophis, Pachyrhachis and Eupodophis, lack a sacral region. Phylogenetic analysis shows that the new fossil is the most primitive (basal) snake known and that all other limbed fossil snakes are closer to the more advanced macrostomatan snakes, a group including boas, pythons and colubroids. The new fossil retains several features associated with a subterranean or surface dwelling life that are also present in primitive extant snake lineages, supporting the hypothesis of a terrestrial rather than marine origin of snakes.

Animals↗
PubMed2000

Are anaphylactic reactions to snake bites immunoglobulin E-mediated?

BACKGROUND: Bites by poisonous European snakes of the genus Vipera lead to local tissue damage and systemic symptoms such as generalized oedema, hypotension, gastrointestinal symptoms, haemolysis and renal dysfunction. Not rarely anaphylactic symptoms like urticaria, localized angioedema and asthma are observed. OBJECTIVE: To look for snake venom-specific immunoglobulin (Ig) E antibodies in patients with a history of bites by European vipers and for cross-reactions with Hymenoptera venoms, that have a similar composition. METHOD: Ten patients with a history of bites by Vipera aspis or Vipera berus were investigated. Three patients had been bitten only once, and two of these had developed only local reactions. Four reported previous allergic reactions to Hymenoptera stings. All patients, 10 Hymenoptera venom-allergic and five nonallergic individuals who served as controls underwent i.c. skin test endpoint titration with snake (V. aspis, V. berus) and Hymenoptera venoms (honey bee, Vespula spp.) and were investigated for specific serum IgE antibodies to the same venoms. RESULTS: Seven of the eight patients with systemic snake bite reactions had both positive skin tests and serum IgE antibodies to snake venoms, while these tests were negative in the two patients with only local reactions to snake bites and all controls. Seven of the eight patients with systemic snake bite reaction also had positive skin tests and specific IgE with one or both Hymenoptera venoms. By RAST-inhibition with sera of four patients with high IgE to both Vipera and Hymenoptera venoms, partial cross-reactivity could be demonstrated in one. CONCLUSIONS: Anaphylactic reactions following snake bites may be IgE-mediated, especially in patients with repeated bites.

Adult↗
PubMed2005

Effects of size and behavior on aerial performance of two species of flying snakes (Chrysopelea).

Aerial locomotion in snakes (genus Chrysopelea) is kinematically distinct from any other type of gliding or powered flight, with prominent, high amplitude body undulations visually dominating the behavior. Because it is not known how flying snakes produce aerodynamic forces in flight, the factors that determine snake flight performance are not clear. In this study, the effects of size and behavior on aerial performance were examined both within a species (C. paradisi) and between two species (C. paradisi and C. ornata), using stepwise multiple regressions to identify relevant variables. Smaller C. paradisi traveled farther than larger snakes at lower sinking speeds, with trajectories that shallowed more quickly and reached lower minimum glide angles. Although wing loading increased faster than expected for isometric size increase, wing loading per se was not responsible for performance differences between large and small snakes. Snakes with higher interactions between relative undulation amplitude and body size transitioned out of the initial acceleration phase at higher airspeeds and sinking speeds, and attained higher maximum airspeeds and horizontal speeds; snakes that used higher average relative amplitudes transitioned out of the initial acceleration phase at higher horizontal speeds. Undulation frequency was not significantly related to any performance variable within C. paradisi and was not significantly different between the two species, suggesting that this variable (in contrast to relative undulation amplitude) may have a minor influence on the aerodynamic mechanism of force production in snake flight. C. paradisi and C. ornata differed significantly in most performance comparisons. C. ornata were more massive than C. paradisi at any given body length and in general exhibited poorer gliding performance than C. paradisi. This study contributes towards understanding how an unconventional body form and kinematics can produce a novel mode of aerial locomotion in a vertebrate glider.

Animals↗
PubMed2000

Drinking in snakes: kinematic cycling and water transport.

Snakes are purported to drink by sucking water into their mouths and then compressing the oral cavity to force water into the oesophagus. Video recordings of drinking behaviour in 23 snakes representing 14 species from three families, combined with simultaneous recordings of water volumes consumed, show that all the snakes vary widely in the amount of water taken in when drinking. This variation is not correlated with kinematic events. Kinematic recordings and indirect measurements of water flow suggest that moving water into the mouth can be decoupled from the processes that move water into the oesophagus and that, infrequently, water may continue flowing into the mouth during both opening (suction) and closing (presumed compression) of the mouth. Drinking in snakes is not a simple, stereotyped behaviour. Different snake species differ in both drinking kinematics and water inflow patterns. Vertical excursions of the mandible are smallest in booids and larger, but highly variable, in different viperids and colubrids. Cyclic movements of the tongue seen in booids are not evident in viperids or colubrids. All the snakes usually take in water at rates far below their potential maximum rate. Although drinking is apparently achieved by suction, a single model cannot explain all water movement patterns in snakes. At a practical level, functional morphological studies of drinking in snakes (and possibly many other animals) must demonstrate that fluid flow actually correlates with kinematic events. Without such an empirical demonstration, interpretation of other measurements (pressure, movement, etc.) is unlikely to produce meaningful models.

Animals↗
PubMed2004

Hypotensive agents from snake venoms.

Many snake venoms contain toxins which produce profound cardiovascular effects. The site of action of these toxins includes cardiac muscle, vascular smooth muscle and the capillary vascular bed. Some snake venoms, for example, contain peptides that inhibit angiotensin converting enzyme and potentiate the biological actions of bradykinin. Other snake venoms contain structural and functional equivalents of mammalian natriuretic peptides. Sarafotoxins are short peptide toxins found in the venoms of snakes from Atractaspis spp. which display potent vasoconstriction properties. These peptides, which share a high degree of sequence identity with endothelins, recognize and bind to endothelin receptors. Snakes have also evolved toxins which block L-type Ca(2+) currents (eg. calciseptine, FS2 toxins, C(10)S(2)C(2) and S(4)C(8)). Snake venom proteins have also been shown to increase vascular permeability. One such protein, increasing capillary permeability protein (ICPP) has recently been isolated from the venom of Vipera lebetina. ICPP is an extremely potent permeability factor with a structure similar to vascular endothelial growth factor (VEGF). Thus there is a vast array of snake toxins with potent cardiovascular activity. Some of these proteins and peptides have proven to be highly selective tools in the study of physiological processes. Others have been used as probes of potential therapeutic targets or as lead compounds in the development of therapeutic agents. Therefore these and other related snake venom proteins hold great promise in the future understanding and treatment of cardiovascular diseases.

Amino Acid Sequence↗
PubMed2000

Use of antivenom serum in snake bite: a prospective study of hospital practice in the Gampaha district.

OBJECTIVE: To record current practices in hospital management of snake bite, especially with regard to use of antivenom serum (AVS). METHODS: Management of all snake bite victims admitted to the four main hospitals of the Gampaha district was prospectively studied during a 5-month period. A pretested data collection sheet was used. Relevant information was obtained from patients, accompanying persons, medical staff and hospital records. RESULTS: 466 patients (M:F = 7:3; 402 adults and 64 children) were admitted following snake bite during the study. The offending snake was identified in 357 (76.6%) cases [172 (36.9%) by examining the dead snake, 185 by identification of the snake in a photograph]. 273 (76.5%) of the 357 admissions were due to hump nosed viper bite. AVS was given to 184 (39.5%) patients, including 99 (36.3%) with hump nosed viper bite. A sensitivity test of AVS was used in all 184 patients. Premedication with hydrocortisone and/or antihistamines before AVS infusion was given to 89 patients. Acute adverse reactions to AVS occurred in 102 (55.4%) patients given AVS. There was no significant difference in the rate of reactions whether premedication was given or not. CONCLUSION: Precise identification of the offending snake was not possible in many instances. Practices that are of no benefit in the treatment of snake bite are still widely used. Acute adverse reactions to AVS are common, and neither hydrocortisone nor antihistamines seem to be of benefit as prophylaxis. Evidence based management guidelines, especially with regard to AVS therapy, are urgently required.

Adolescent↗
PubMed2000

The snake as the symbol of medicine, toxicology and toxinology.

We investigated the meaning and the roots of the snake's usage as a symbol of medicine, the medical profession, toxicology and toxinology by examining mythological, archeological data and a variety of texts from the ancient Greek world. The snake figure was associated with Asclepios, the ancient Greek God of medicine, and possessed benevolent properties. It was believed to be able to cure a patient or a wounded person just by touch. The snake is also connected with pharmacology and antisepsis, as snakes possess an antivenom against their own poison. The snake is related to sciences associated with poison and death, such as toxicology and toxinology, and it also implies a metaphysical idea. It is connected with the underworld, not only because it crawls on the ground, but because it can bring death, connecting the upper with the underground world. The ability of the snake to shed its skin has been associated with the circle of life, and the renaissance spirit also, ever since early Hellenic antiquity. Consequently, as a symbol of the modern medical profession, toxicology and toxinology, the snake twisted around a stick or the snake beside a pharmapeutic cup, which also implies the use of medicines or even poison, has its roots in the ancient Mediterranean area as proven by the archeological data combined with literary references. Its benevolent as well as its poisonous properties could be paralleled by the similar properties of medicines.

Animals↗
PubMed1997

Cardiovascular responses of snakes to hypergravity.

Snakes have provided useful vertebrate models for understanding circulatory adaptation to gravity, attributable to their elongate body shape and evolutionary diversificaton in terms of ecology and behavior. Recently we have studied cardiovascular responses of snakes to hypergravic acceleration forces produced acutely in the head-to-tail direction (+Gz) on a short-arm centrifuge. Snakes were held in a nearly straight position within a horizontal plastic tube and subjected to a linear force gradient during acceleration. Carotid blood flow provided an integrated measure of cardiovascular performance. Thus, cardiovascular tolerance of snakes to stepwise increments of Gz was measured as the caudal Gz force at which carotid blood flow ceased. Tolerance to increasing Gz varies according to adaptive evolutionary history inferred from the ecology and behavior of species. With respect to data for six species we investigated, multiple regression analysis demonstrates that Gz tolerance correlates with gravitational habitat, independently of body length. Relative to aquatic and non-climbing species, carotid blood flow is better maintained in arboreal or scansorial species, which tolerate hypergravic forces of +2 to +3.5 Gz. Additionally, semi-arboreal rat snakes (Elaphe obsoleta) exhibit plasticity of responses to long-term, intermittent +1.5 Gz stress. Compared to non-acclimated controls, acclimated snakes show greater increases of heart rate during head-up tilt or acceleration, greater sensitivity of arterial pressure to circulating catecholamines, higher blood levels of prostaglandin ratios favorable to maintenance of arterial blood pressure, and medial hypertrophy in major arteries and veins. As in other vertebrates, Gz tolerance of snakes is enhanced by acclimation, high arterial pressure, comparatively large blood volume, and body movements. Vascular studies of snakes suggest the importance to acclimation of local responses involving vascular tissue, in addition to centrally mediated responses to fluid shifts.

Adaptation, Physiological↗
PubMed1987

The management of snake and spider bites in the southeastern United States.

Of all snake bites reported in the United States of America each year, 75 per cent occur in the states that form the Southeastern Surgical Congress. Pit vipers, coral snakes, and exotic imported snakes are all found in that area. Deaths from those snake bites are rare, but morbidity is high and it is often due to overtreatment rather than undertreatment. Treatment in the field is rarely necessary for the victim who is less than 1 hour away from definitive care. The type and size of the snake and the age, size, and health of the patient are important guides to therapy. Envenomation may not occur. When envenomation occurs from pit viper bites, antivenom is not always necessary, and its inherent dangers (serum sickness and possible hypersensitivity) must be weighed against the severity of systemic and local manifestations. All coral snake bites resulting in envenomation must be treated vigorously with coral snake antivenom. The Oklahoma City Poison Control Center can guide the treatment of bites from exotic snakes. The most frequently encountered toxic spider bites in the Southeast are those of the black widow and brown recluse spiders. The symptoms of black widow envenomation are best controlled with calcium gluconate or a muscle relaxant. Antivenom should be reserved for severe reactions. Brown recluse necrotic lesions are best controlled with dapsone.

Humans↗
PubMed1985

Plasma concentrations of chloramphenicol in snakes.

Plasma chloramphenicol concentrations after a subcutaneous injection were studied in 87 snakes of 16 different species. The biological half-life of chloramphenicol varied from 3.3 hours in the indigo snake (Drymarchon corais couperi) to 22.1 hours in the midland water snake (Nerodia sipedon). A single dosage of 50 mg of chloramphenicol/kg of body weight produced plasma concentrations greater than 5 micrograms/ml for nearly 72 hours in 2 species of water snakes (Nerodia erythrogaster, Nerodia sipedon), for 24 hours in the Burmese python (Python molurus bivittatus), and for less than 12 hours in the gray rat snake, Indigo snake, and eastern king snake (Elaphe obsoleta spiloides, Drymarchon coraise couperi, and Lampropeltis getulus getulus). A dosage of 50 mg/kg administered to water snakes every 72 hours for 18 days maintained a minimum plasma concentration of chloramphenicol between 2 and 5 micrograms/ml.

Animals↗
PubMed1978

Metabolism of homologous and heterologous serum proteins in garter snakes (Thamnophis ordinoides).

The half life (T1/2) of serum immunoglobulin (Ig) and albumin from snakes and mammals were determined in both garter snakes (Thamnophis ordinoides) and mice (Mus musculus). Metabolism of serum proteins in snakes was similar to mammalian protein metabolism in that homologous serum albumin had shorter T1/2 (16 days) than IgG (38 days). Also, reptilian and mammalian serum proteins had a relatively longer T1/2 when injected into closely related species. Thus mammalian serum Ig (rabbit gamma globulin (RGG)) had a shorter T1/2 (6.3 days) in snake than did homologous snake IgG (38 days), whereas in mice, RGG had a longer T1/2 (3.8 days) than snake Ig (0.9 days). Differences between metabolism of homologous and heterologous albumins were apparent only in snakes in which the T1/2 of homologous albumin was approximately 8-fold greater than mammalian albumin. These results indicate that metabolism of both Ig and albumin in snakes is regulated by specific receptors whereas albumin receptors have been difficult to demonstrate in mammals. The results of this study suggest that one of the factors determining the metabolism of a protein is its foreignness to the host perhaps because of receptor cross reactions.

Animals↗
PubMed1981

The primary structure of snake (Zaocys dhumnades dhumnades, Cantor) insulin.

Snake insulin is isolated and crystallized from the pancreas of non-venomous snake (Zaocys dhumnades dhumnades, Cantor). The crystalline form is not rhombohedral but dodecahedral. The primary structure has been determined with the aid of an LKB solid-phase sequencer. In the primary structure of snake insulin, the presence of B5 Arg, B29 Arg, B16 Phe, B25 Tyr and B18 Ile is unusual in comparison with insulins from mammals, birds and fishes. However, the snake insulin we studied is very similar to rattle snake insulin, with the exception that A15 is glutamic acid instead of glutamine and B30 is threonine instead of serine. These differences are consistent with the higher acidity of the snake insulin we studied and with the threonine and serine content in amino acid analysis. The B10 residue of the snake insulin we studied is still histidine. The formation of dodecahedral crystals of the snake insulin has been discussed in connection with the presence of this histidine.

Amino Acid Sequence↗
PubMed1982

Laboratory observations of aggregative behavior of garter snakes, Thamnophis sirtalis: roles of the visual, olfactory, and vomeronasal senses.

Two experiments were conducted to determine (a) whether male garter snakes (Thamnophis sirtalis) require a functional vomeronasal or olfactory system to return to previously preferred shelter locations and (b) the sensory modalities used by snakes to aggregate in the absence of previously deposited chemical cues. In Experiment 1, snakes with vomeronasal nerve lesions did not return to previously preferred shelter locations when tested individually. However, when tested with a group that included "control" animals, they returned to previously preferred shelters. The shelter-selection behavior of snakes with olfactory nerve lesions improved postoperatively, whereas the behavior of animals with sham lesions was unchanged. In Experiment 2, snakes were tested for aggregation in aquaria in which the substrate and other contents were cleaned between trials. After blindfolding or after olfactory nerve cuts, snakes aggregated at normal levels. When the snakes' vomeronasal ducts were sutured closed, aggregation scores were significantly depressed, although two of the three groups with vomeronasal duct sutures did aggregate just above chance levels. These studies indicate that use of chemical signals by garter snakes in shelter selection and aggregation is mediated by the vomeronasal system and that neither the olfactory nor the visual system is critical for these behaviors.

Animals↗