Kinds Of Predators Research Articles

Functionally novel invasive predator eradicates herbivores of a littoral community

In the Archipelago Sea as in most other parts of the Baltic Sea, the bladder wrack (Fucus vesiculosus) is a foundation species of the littoral communities of the rocky shores. It sustains a community of epiphytic algae, herbivorous crustaceans and molluscs and various fish. Recently we have noticed a steep decline in the occurrence of the herbivorous crustaceans and molluscs in many sites in the Archipelago Sea. We hypothesise that a key factor contributing to this decline is the recent introduction of the Harris mud crab (Rhithropanopeus harrisii), which was first sighted in 2009 in this region. Importantly, because there are no native crabs in the northern parts of the Baltic Sea, the mud crab is a completely novel kind of predator in the ecosystem and the herbivorous crustaceans and molluscs may be particularly susceptible to it. Here, we document a dramatic decline of the typical herbivores occurring on the bladder wrack, possibly indicating an ongoing regime shift, by comparing our recent samples from across the Archipelago Sea with data collected a decade before the sighting of the mud crab. Moreover, we demonstrate a spatio-temporal association between the decline, particularly of the key herbivore species, the isopod Idotea balthica, and the establishment of the mud crab. We also present experimental evidence for a strong predator-prey -link between the mud crab and the isopod I. balthica. Finally, we discuss the possible consequences of the community change and scrutinise alternative explanations for our observations.

Investigating how different classes of nest predators respond to the playback of the begging calls of nestling birds

Begging brings benefits and costs for nestling birds: it can indicate their needs to their parents, but it can also be a cue used by predators to find the nest. The costs, like many variables related to nest predation, can be specific to what kinds of predators are present and their auditory capabilities. These costs and benefits could also be affected by human noise, as noise could disrupt communication to parents and eavesdropping by predators, although human-produced noise might be easily ignored if predators can hear high-frequency components of the begging. We studied nest predation on a generalist bird, the Red-whiskered Bulbul (Pycnonotus jocosus), in a tropical forest in which there are many kinds of nest predators, including birds, mammals and reptiles. In 20 natural nests in which artificial eggs were placed, and subsequently in 140 artificial nests, we broadcast recordings of begging nestlings, with and without traffic noise, at two volume levels. We hypothesized that playback would increase predation relative to a silent control, and that mixing in traffic noise with the begging would decrease predation, as the begging signal was masked. However, we hypothesized that some predators, particularly small mammals with sensitive high-frequency hearing, might ignore the traffic noise. We found that predation was lowest for the control treatment, and lower for treatments mixed with traffic noise than for those without it. Small mammals, however, showed an unexpected pattern, displaying less nest predation in the treatments with traffic noise. Our results demonstrate the human-associated noise can disturb nest predators and influence which kinds of predators use begging to locate nests.

A stage-structured predator-prey model with predation over juvenile prey

We formulate and study a stage-structured predator-prey model of Beddington–DeAngelis-type functional response to investigate the impact of predation over the immature prey by the juvenile predator. This kind of predation has been omitted in many of the mathematical models, mainly due to the great challenges in mathematical analysis associated with the complicated exponential and state-dependent prey maturation rate term. We establish the threshold dynamics determined by the net reproductive number of the predator population ℜ0. The predator-free equilibrium is globally stable if ℜ0 < 1, while the predator persists if ℜ0 > 1. Numerical simulations are conducted to illustrate our analytical results. Our results show that an appropriate interference among predators may drive the state of internal coexistence into asymptotic stability.

Risks for larvae mediated by plasticity in hatching

AbstractRisks associated with benthic and planktonic development can be mediated by plasticity in hatching. The ability to delay hatching while awaiting favorable planktonic conditions, combined with the ability to accelerate hatching when encapsulated offspring are at risk, should be advantageous. We tested this predicted association of hatching plasticities with a barnacle. In the winter, broods of barnacles (Balanus glandula) reached hatching‐capable stages at widely varying times, but these broods hatched in the spring within about 2 weeks, consistent with a synchronizing environmental stimulus for hatching. In contrast, the same adults held subsequent broods (during later spring and summer) briefly. Either an environmental stimulus for hatching was not needed later in the season, or it was more frequently present. Dissections of brood lamellae that scattered smaller clumps of the encapsulated nauplii induced hatching. Crabs eating brooding adults had a similar effect: crabs broke the barnacles' tests, and many nauplii hatched. In contrast, when whelks ate barnacles, they left the barnacles' wall plates and opercula in place, and few nauplii were released. In some cases, numerous hatched nauplii were trapped within the test of the killed mother. At a field site with abundant whelks, many dead barnacles had opercular plates in place. Plasticity in hatching of broods adjusted risks for planktonic larvae against risks of death of the parent before release of embryos, but escape or death of brooded offspring depended on the kind of damage to the brooding mother and thus on the kind of predator. Although both predators killed brooding parents, subtle snails imposed a greater risk than crushing crabs.

The global contribution of forage fish to marine fisheries and ecosystems

AbstractForage fish play a pivotal role in marine ecosystems and economies worldwide by sustaining many predators and fisheries directly and indirectly. We estimate global forage fish contributions to marine ecosystems through a synthesis of 72 published Ecopath models from around the world. Three distinct contributions of forage fish were examined: (i) the ecological support service of forage fish to predators in marine ecosystems, (ii) the total catch and value of forage fisheries and (iii) the support service of forage fish to the catch and value of other commercially targeted predators. Forage fish use and value varied and exhibited patterns across latitudes and ecosystem types. Forage fish supported many kinds of predators, including fish, seabirds, marine mammals and squid. Overall, forage fish contribute a total of about $16.9 billion USD to global fisheries values annually, i.e. 20% of the global ex‐vessel catch values of all marine fisheries combined. While the global catch value of forage fisheries was $5.6 billion, fisheries supported by forage fish were more than twice as valuable ($11.3 billion). These estimates provide important information for evaluating the trade‐offs of various uses of forage fish across ecosystem types, latitudes and globally. We did not estimate a monetary value for supportive contributions of forage fish to recreational fisheries or to uses unrelated to fisheries, and thus the estimates of economic value reported herein understate the global value of forage fishes.

A Celtic Gloss in the Hesychian Lexicon

The well known lexicon, prepared by Hesychios of Alexandria (5th or 6th cent. AD), contains a number of glosses which are defined as “Celtic” or as “Galatian”. However, most Hesychian glosses appears with no ethnic designation. Some of them can be convincingly treated as Celtic (especially Galatian) terms. There is also the case which is connected with the following gloss: mátan · hē lynx. énioi dè matakòs è matakón “mátan [means] she-lynx. Some [call lynx] matakós or matakón.” These three names for ‘lynx’ seem to possess exact and convincing equivalents only in the Celtic Insular languages. Celtic *mat- ‘a kind of predator’ (1. lynx, 2. bear, 3. fox), *matākós m. ‘id.’ (1. lynx, 3. fox). 1. Continental Celtic mátan gl. hē lynx; also matakòs and matakón ‘lynx’ (Hesych.); 2. OIr. math (gen. sg. matho) m. (u-stem) ‘bear’ (&lt; Celt. Goid. *matu-); see Gaul., OBritt. PN Matugenus m. Hisp.-Celt. PN Matugenus, Matucenus, OIr. PN Mathgen, OW. PN Madyein (&lt; Celt. *Matu-genos, liter. ‘son of bear’); Scottish Gaelic mathan m. ‘bear’ (&lt; Celt. Goid. *mat-agnos), also Sc. Gael. mathghamhuin ‘bear’, Early Ir. mathgaman ‘id.’; 3. OW. madawg, W. madog m. ‘fox’ (&lt; Celt. Britt. *matākos); see Gaulish PN Matacus, Old Brittonic PN Matucus, Old Welsh PN Matauc, Matoc, Breton PN Matoc, later Matec; W. madyn m. ‘fox’, maden f. ‘a small she-fox, vixen’ (&lt; Celt. Britt. *matinos m. vs. *matinā f.); see also Gaul. PN Matinus m., Matina f. I discuss the Celtic origin of the Hesychian gloss, the etymology of the Celtic words, as well as the problems of the original meaning.

Designing Effective Alarm Sounds

Designing Effective Alarm Sounds

Who brought in the rabbits? Taphonomical analysis of Mousterian and Solutrean leporid accumulations from Gruta do Caldeirão (Tomar, Portugal)

In the Iberian Peninsula, leporids, and specifically rabbits, play a key role in the understanding of hunter-gatherer economies. They appear to have been especially important in the Tardiglacial, when large numbers of small prey animals and of the European rabbit ( Oryctolagus cuniculus) in particular, are a ubiquitous feature of faunal assemblages from archaeological sites. Since a large number of non-human predators can also contribute to the formation of such assemblages, the ability to discriminate between bones accumulated by humans and by other kinds of predators is a key prerequisite to their interpretation. On the basis of systematic actualistic studies carried out on modern leporid remains produced by mammalian terrestrial carnivores, nocturnal and diurnal raptors, and humans, we identified diagnostic taphonomic indicators of the different predators. In this paper, the patterns observed on the modern material are applied to the taphonomical analysis of two archaeological samples of rabbit and hare remains from Mousterian and Solutrean layers of Gruta do Caldeirão, a cave site located in Central Portugal. Our results suggest that Eagle Owl ( Bubo bubo) were mainly responsible for the Mousterian accumulations, whilst the Solutrean ones were most likely the result of human activity. These data support the notion that, in Iberia, significant reliance on rabbits does not become a feature of subsistence strategies until later Upper Palaeolithic times.

Growth, feeding and ecological roles of the mixotrophic and heterotrophic dinoflagellates in marine planktonic food webs

Planktonic mixotrophic and heterotrophic dinoflagellates are ubiquitous protists and often abundant in marine environments. Recently many phototrophic dinoflagellate species have been revealed to be mixotrophic organisms and also it is suggested that most dinoflagellates may be mixotrophic or heterotrophic protists. The mixotrophic and heterotrophic dinoflagellates are able to feed on diverse prey items including bacteria, picoeukaryotes, nanoflagellates, diatoms, other dinoflagellates, heterotrophic protists, and metazoans due to their diverse feeding mechanisms. In turn they are ingested by many kinds of predators. Thus, the roles of the dinoflagellates in marine planktonic food webs are very diverse. The present paper reviewed the kind of prey which mixotrophic and heterotrophic dinoflagellates are able to feed on, feeding mechanisms, growth and ingestion rates of dinoflagellates, grazing impact by dinoflagellate predators on natural prey populations, predators on dinoflagellates, and red tides dominated by dinoflagellates. Based on this information, we suggested a new marine planktonic food web focusing on mixotrophic and heterotrophic dinoflagellates and provided an insight on the roles of dinoflagellates in the food web.

Alarm calls of the Southern House Wren Troglodytes musculus: variation with nesting stage and predator model

Alarm calls given by parents when risk is detected during nesting may be considered a form of parental defense. We analyzed variations in callings of breeding pairs of the Southern House Wren Troglodytes musculus during the nesting cycle and when faced with different predator models. Nesting birds were exposed to stuffed models at different nesting stages (early and late during incubation, and nests with younger and older nestlings). Nests were also exposed to different predator models where the calling response of breeding adults and acoustic structure variations of the calls were analyzed. The presence of a predator model increased the parents’ alarm calls along the nesting stage. This result supports the hypothesis that the higher the nest reproductive value, the higher the nest defense performed by the Southern House Wren. However, it also supports the notion that alarm calls could be used by parents to silence nestlings and reduce their detectability. Alarm calls also varied according to the predator model presented. We suggest that alarm calls variations of Southern House Wrens could encode information about the kind of predator and the risk envisaged through variations of call rates.

INDUCIBLE DEFENSES IN MULTIPREDATOR ENVIRONMENTS: CYCLOMORPHOSIS IN DAPHNIA CUCULLATA

Phenotypically plastic defenses are strategies to reduce predation risk in variable environments. Predator-induced formations of protective devices in cladocerans are prominent examples of phenotypically plastic defenses. To understand the adaptive value of a defense, it is better to investigate its effects in a multipredator context, instead of merely concentrating on a two-species interaction. Small cladocerans such as Daphnia cucullata are prey items for many aquatic invertebrate predators and thus comprise a useful model system to investigate defenses and their effects. In this study, we tested the hypothesis that the helmets of Daphnia cucullataare inducible with chemical cues from different kinds of predators and that they act as a generalized defense offering protection against several predators, each using a different hunting strategy. Results from our induction experiment show that chemical cues released from Chaoborus flavicans, Leptodora kindtii, and Cyclops sp. induce significantly longer helmets and tail spines and thus act as proximate factors for cyclomorphosis in Daphnia cucullata. Our predation experiments revealed that the induced morphological changes offered protection against each of the predators tested. Interestingly, the protective mechanisms and the prey size classes which were protected differed between predator systems. Our results suggest that phenotypic plasticity in Daphnia cucullata evolved as a ''dif- fuse'' coevolution against different invertebrate predators which selectively feed on small prey items. The additive benefits may increase the adaptive value and thus facilitate the evolution and persistence of this generalized defense.

Predation of Small and LargeOrgyia leucostigma(J. E. Smith) (Lepidoptera: Lymantriidae) Larvae by Vertebrate and Invertebrate Predators

In this study, we asked whether different predatory assemblages (i.e., flying invertebrates, crawling invertebrates, and birds, representing vertebrate predators) in a temperate forest impose significantly different levels of predation on larvae of Orgyia leucostigma (J. E. Smith), the whitemarked tussock moth and also whether the size of whitemarked tussock moth larvae influence invertebrate and vertebrate predation. Predation by species in vertebrate and invertebrate predator assemblages on two sizes of O. leucostigma larvae on box elder, Acer negundo (L.) (Sapindales: Aceraceae) was compared using exclusion cages. Cages covered with mesh of different sizes and sticky barriers were used to exclude different kinds of predators (i.e., birds, flying invertebrates, and crawling invertebrates). Five small and five large larvae were placed on box elder saplings. Predation by birds was the greatest source of mortality of large larvae when compared with that caused by flying and crawling invertebrates. Predation played an insignificant role in the disappearance of small larvae whose disappearance was associated with their dispersal behavior.

Parasite-Associated Phenotype Modifications in Threespine Stickleback

The threespine stickleback fish, Gasterosteus aculeatus, is parasitized by the tapeworm Schistocephalus solidus in freshwater habitats. The competency of the parasite to infect a definitive host, one of many piscivorous birds, is associated with behavioral changes in parasitized stickleback that are likely to increase the chance of transmission to a definitive host. Over a limited geographical range, large tapeworm size is also associated with demelanization, a phenotypic change in the stickleback host that involves a dramatic loss of melanin in the skin and, simultaneously, a darkening of the eye. We demonstrate that stickleback harboring a worm large enough to be infective to a definitive host exhibit behavioral shifts likely to enhance transmission, but that these changes are substantially magnified in demelanized individuals, all of which were infected by large tapeworms. The results were similar whether we used a model of a bird flown over an aquarium, or a preserved trout moved to simulate attack under field conditions. Because changes in the levels of response to both kinds of predators were similar, we infer that behavioral modifications that enhance susceptibility to visually hunting predators that are definitive hosts also enhance susceptibility to visually hunting predators (e.g. trout) that are not. In lakes where predatory fishes are common, the impact on S. solidus transmission could be substantial. Although other studies have suggested that positive buoyancy, forcing infected fish to remain near the surface, is one cause of these behavioral shifts, we detected no differences in water column position among unparasitized and parasitized classes of stickleback. Instead, infected stickleback appeared to move sluggishly and were less likely to respond to simulated attacks than were uninfected fish, and the behavioral shift was most dramatic in demelanized stickleback.

QUANTIFYING PREDATION BY UMMELIATA INSEC‐TICEPS BOES. ET STR. (ARANEAE: LINYPHIIDAE) ON RICE PLANTHOPPERS USING ELISA*

Abstract An enzyme‐linked immunosorbent assay (ELISA) has been developed to quantify predation by Ummeliata insecticeps Boes. et Str. on rice planthoppers in paddy fields in Dasha Township, Guangdong Province. The assay was completely specific for rice planthopper materials. The detection periods for antigens after an adult of U. insecticeps had fed on three 3–5th instar nymphs of white‐back planthopper (WBPH), Sogatella furcifera (Horvath), and brown planthopper (BPH), Nilaparvata lugens (Stal), at room temperature were 96 h and 120 h, respectively. The proportion of individual species of predators scoring positive ranged from 19. 05% to 47. 34% for WBPH, and from 9. 25% to 66. 67% for BPH in the early rice season. Although the numbers of the rice planthoppers consumed by U. insecticeps increased with increasing prey densities, the predation rates declined. When rice planthopper densities were low, the predation rates were relatively high. This kind of predation can explain why the rice planthoppers have never reached outbreak levels in rice fields in Dasha Township since 1973.

Synergistic Predation, Density Dependence, and Population Regulation in Marine Fish

Understanding natural causes of density dependence is essential for identifying possible sources of population regulation. Field experiments on a model system of coral reef fishes showed that small juveniles of Chromis cyanea suffer heavy mortality that is spatially density-dependent only in the presence of two suites of predators: transient piscivores attacking from above, and reef-resident piscivores attacking from below. In the absence of either kind of predator, early mortality of Chromis is virtually density-independent. Because piscivores may have regulatory roles in this and similar marine systems, overfishing these predators may have ramifications for the remainder of the exploited community.

Daphnia Behaviour as a Bioassay of Fish Presence or Predation

1. Fish cues are associated with changes in Daphnia behaviour, however, the causes of these responses are generally unknown. 2. Two kinds of experiments were done in order to test whether the predator cue inducing changes in Daphnia galeata mendotae was : in solution and molecular ; whether the cue came from fish or from other Daphnia ; whether the presence of fish was sufficient to generate the cue ; whether a predator had to be eating and digesting prey ; if the type of food was important. 3. Results of the two experiments indicated that : the cue was molecular. It was only generated by fish digesting live food, unlike bioassay experiments on Daphnia magna. It did not require that naive Daphnia were pre-conditioned. There was between-clone variation for responses to water conditioned by fish feeding on commercial worms, whereas all the clones tested in these experiments responded strongly to fish feeding on Daphnia. 4. Between-genotype variation for specificity and sensitivity to chemical cues suggests the potential for different Daphnia species in different habitats to evolve disparate responses to the same kind of predator.

Integrated Pest Management: A Grower's Perspective

Taft Farms is an 80-ha mixed-vegetable farm growing primarily for retail sales. From a business point of view, we buy products we don’t raise and contract other growers to produce items according to our distinct growing philosophy. (We use organic methods as far as they go and use commercial nutrients to pick up the slack and keep things in balance. Pesticides are used only as a last resort to save a crop.) An example of this is raspberries. We purchase the entire crop of another grower as long as he follows our methodology. We agree on a price beforehand, and I supply him with all necessary support and materials. We have a highly diverse operation-perhaps too diverse. Life would be a lot simpler if we could narrow it down and focus on a few crops, but in a sense our unusual approach has trapped us. Our customers are demanding even greater diversity. We raise a number of crops for “pick your own.” Response is tremendous, and we find that customers tend to buy more than they would ordinarily. When we started out as growers in the 1950s, we used few pesticides, largely because we didn’t know about their availability. As time went on, we used as many chemicals as anyone in the business. Cost factors were originally the reason for our minimizing pesticides. As resistance grew, it didn’t take a rocket scientist to figure out that something was wrong. We stopped spraying by the calendar, started a meaningful rotation schedule, and started to monitor pest activity a lot more closely. We found ourselves getting more and more involved with understanding the nature of the beast and minimizing the conditions that were favorable to it. With this approach we were able to virtually eliminate most fungicide and insecticide sprays by 1980. Eventually, some guidelines were established to determine whether a control measure had to be employed. Again, I emphasize that these guidelines were based solely on economics. Environmental concerns had not yet hit home, and pressure from our customers ranged from light to nonexistent. In the early 1980s, The Univ. of Massachusetts announced the beginning of the Integrated Pest Management program. Soon I found that what we had been doing already was pretty much what they were doing, but they were definitely more sophisticated in the way they did it. The numbers for our “economic thresholds” were virtually the same. With the resources of the Univ. of Massachusetts and other universities we were able to refine our efforts and eventually eliminate the use of most pesticides without sacrificing yield or quality. I should point out that we are relatively isolated and not easily influenced by someone else’s resistance problems. Moving in a nonpesticidal direction was considerably easier for us than it would be for anyone located in a heavily farmed area. Our focus now is toward keeping pest levels below the point where action has to be taken. We have used many kinds of predators. Especially successful have been several Trichogramma species and predatory yeasts. Most other predators are at sufficient levels to keep their prey in check. We are now working with nutrition as a means of pest control. I firmly believe that stress from lack of proper nutrition, especially in the minor elements, is a major factor in proper pest management. When we manage nutrients properly and keep stress of any kind to a minimum, pest control is not only much easierbut in many cases not needed at all. Because we could not find plant foods of the types we needed, we

Resource partitioning between intertidal predatory crabs: interference and refuge utilization

Acanthocyclus gayi Milne-Edwards et Lucas and A. hassleri Rathbun are two intertidal predatory crabs that coexist along the rocky coast of Chile. The two species are morphologically similar and remain hidden inside refuges during diurnal low tide periods. Their microhabitat distributions and diets were studied at two sites in central Chile. Juveniles of each species were found coexisting in three microhabitats (mussel beds, rock crevices and kelp holdfasts), although most lived amongst mid intertidal mussels. Most recruits were observed in mussel beds. In contrast to juveniles, adults were segregated by microhabitat. Most adults of A. hassleri were in galleries built through mussel beds, while adults of A. gayi were found only in rock crevices and holdfasts of the kelp Lessonia nigrescens Bory. Diets of both species were similar, even between adults. Because of the large dietary overlap observed between juveniles and adults of the two species, and the apparent abundance of food in the field, segregation between adult crabs did not seem to result from competition for food. Because thickness of the mussel bed was positively correlated with the density and size of crabs, there may be a paucity of suitable living spaces for adult crabs. In contrast to juvenile crabs, which shared refuges during low tides, adults aggressively defended refuges, both intra- and interspecifically. Laboratory and field experiments showed strong asymmetry in interspecific contests. Adults of A. hassleri, which have a proportionally larger master chela, were able to aggressively exclude adults of A. gayi from refuges provided in the laboratory, and from galleries in mussel beds in the field. Segregation between adult crabs seems to be the outcome of interference competition for refuges. Refuges are readily available for small crabs and hence they coexist in the same microhabitats. Refuges are hypothesized to provide protection for Acanthocyclus crabs from visual predators, such as the kelp gull Larus dominicanus. Analysis of relative predation pressure on crabs by gulls indicates that galleries in mussel beds constitute an effective refuge against this kind of predator.

Frequency-dependent predation, crypsis and aposematic coloration.

Frequency-dependent predation may maintain or prevent colour pattern polymorphisms in prey, and can be caused by a variety of biological phenomena, including perceptual processes (search images), optimal foraging and learning. Most species are preyed upon by more than one predator species, which are likely to differ in foraging styles, perceptual and learning abilities. Depending upon the interaction between predator vision, background and colour pattern parameters, certain morphs may be actively maintained in some conditions and not in others, even with the same predators. More than one kind of predator will also affect stability, and only slight changes in conditions can cause a transition between polymorphism and monomorphism. Frequency-dependent selection is not a panacea for the explanation of variation in animal colour patterns, although it may be important in some systems.

New archaeogastropod limpets from hydrothermal vents; superfamily lepetodrilacea I. Systematic descriptions

Nine new species, six in the new genus Lepetodrilus and three in the new genus Gorgoleptis , are proposed in two new families, which together compose the new archaeogastropod superfamily Lepetodrilacea, as yet known only from the deep-sea hydrothermal-vent habitat in the eastern Pacific. Shells are limpet-shaped, of non-nacreous aragonite, with tough periostracum enveloping the shell edge. The apex is posterior, in some species projecting posteriorly, and deflected to the right. Sculpture is lacking or of beads or imbricate radial ribs. The muscle scar is horseshoe-shaped and narrowed posteriorly. The radula is rhipidoglossate and unique in forming a V-alignment of lateral teeth descending toward the rachidian. The families differ in morphology of the first lateral tooth, morphology of the ctenidium, and in placement of the penis: on the right ventral side of the neck in Lepetodrilidae and an outgrowth of the left oral region in Gorgoleptidae. Gorgoleptidae further differ in retaining the operculum and in having a posterior periostracal band shielding the posterior viscera and extending adjacent to the operculum. Anatomy is treated in part II by Fretter ( Phil. Trans. R. Soc. Lond. B 318, 33 (1988)). Three species ( L. pustulosus , the type species of Lepetodrilus , L. elevatus and L. cristatus ) are known from the Galapagos Rift and two sites on the East Pacific Rise, near 21° N and 13° N. One species, L. ovalis , is known from the two sites along the East Pacific Rise. The remaining species are as yet known only from single sites: L.guaymasensis from the Guaymas Basin, L. fucensis from the Juan de Fuca and Explorer Ridges, G. emarginatus from 21° N, G. spiralis from 13° N, and G. patulus from the Galapagos Rift. Only one of the broadly distributed species, L. elevatus , exhibits sufficient geographical variation to warrant the recognition of a subspecies, L. elevatus galriftensis , n. subsp., at the Galapagos Rift. These species are known only from sites exposed to warm hydrothermal effluent, not from the hotter environments of the black smokers or from cold sulphide seeps. Shell characters are most similar to the ‘tapersnout’ superfamily, yet to be described, from which these species differ in having pitted sculpture on the protoconch. The Jurassic to early Cretaceous Symmetrocapulidae had similar shell proportions but were much larger; the Symmetrocapulidae are best considered an archaeogastropod sister group. The hydrothermal-vent habitat has been available throughout geological time; hydrogen sulphide toxicity should prevent invasions of new kinds of predators, thus promoting stability and longevity of species established in this community. Differences from other archaeogastropods at the superfamily level suggest that the origin of the Lepetodrilacea took place in the late Palaeozoic to early Mesozoic, the time at which other living archaeogastropod superfamilies appeared. The rift-vent habitat was most likely entered via shallow to successively deeper sites along ridge crests. Unique anatomies and radular characters are considered remnants of early archaeogastropod diversity from the period in which archaeogastropods were the dominant gastropods in shallow seas.