Escape responses to three herbivorous gastropods to the predatory gastropod Conus textile.
ABSTRACT The herbivorous gastropods Strombus canarium, Lambis lambis, and Trochus pyramis evince escape responses, probably mediated by distance chemoreception, in the presence of the predatory gastropod Conus textile.In Strombus and Lambis, the response has two components: increase in the absolute rate of locomotion, and direction of locomotion away from the predator. When placed in the presence of C. textile, T. pyramis began moving, generally in the direction it faced.In control observations, a specimen of S. canarium moved at a mean rate of 2·7 mm/sec, by the leaping mode of locomotion characteristic of this and related genera. In the presence of C. textile, the rate increased to 6·8 mm/sec, due primarily to shortening of the lag or recovery period between leaps. In the presence of C. textile, a specimen of L. lambis moved at a rate of 11·9 mm/sec in the same manner as Strombus. In the presence of C. textile, a specimen of T. pyramis progressed at a rate of 1·9 mm/sec, by pedal locomotory waves.Comparison with absolute rates of locomotion by pedal locomotory waves in other marine gastropod molluscs leads to the conclusion that the leaping of Strombus and Lambis does not enable these gastropods to maintain a more rapid long-term rate of movement, but it confers a striking increase in agility, and a single leap provides an almost instantaneous increase in distance from a potential predator.
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ABSTRACT: Past research has suggested that the humped conch (Strombus gibberulus), a species common in many prehistoric archaeological sites in the Pacific, declines in size and/or abundance over time. Explanations for this phenomenon largely revolve around the possibility that they were overharvested by human populations. In this study, we measured the length and width of over 1400 individual specimens of S. gibberulus shells recovered from the site of Chelechol ra Orrak in Palau, western Micronesia, in deposits dating from ca. 3000 BP to the present. Statistical analysis indicates that in contrast to previous reports, there is a significant size increase for this taxon through time which may be the result of a combination of anthropogenic and environmental factors. We discuss variables influencing mollusc size and suggest that, given the complexities of their interactions and the data limitations of archaeomalacological assemblages, unambiguous determination of the cause(s) of molluscan size change may not always be possible.Journal of Archaeological Science 08/2013; · 1.89 Impact Factor
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ABSTRACT: On an intertidal reef flat at Orpheus Island on the Great Barrier Reef, the gastropods Turbo brunneus and juvenile Trochus niloticus share the same habitat with the predatory gastropod Thais tuberosa. To determine if the two prey species differed in their antipredator behaviour and interactions with the predator, we examined: (1) the distributional pattern of the three species in the field; (2) the proportion of mortality attributable to non-crushing predators (i.e. Thais tuberosa) in T. brunneus and T. niloticus, determined by the frequency of freshly dead and undamaged shells; and (3) the response of T. brunneus and T. niloticus to T. tuberosa in laboratory and field experiments. We compared the responses of hatchery-reared and wild juvenile T. niloticus to determine if lack of previous exposure to the predator affected the behaviour of cultured juveniles. Finally, (4) we studied prey choice by Thais tuberosa.We found that: (1) the field distribution of all three species showed high overlap and prey and predator were often found in close proximity; (2) the proportion of recently-killed, undamaged shells was 28% for T. brunneus and 10% for T. niloticus; (3) T. brunneus and T. niloticus responded very differently to the predator: Turbo brunneus showed a conventional flight escape response, moving nine times faster than normal when close to T. tuberosa. The flight response was observed in all trials with T. brunneus in the laboratory, but only in 52% of trials in the field. In contrast, T. niloticus did not change speed but instead released a white mucus in the presence of the predator. Response in the field was also less intense than in the laboratory. Cultured and wild T. niloticus showed the same response when exposed to T. tuberosa. although cultured juveniles were, on average, slightly more active than wild juveniles. Lastly, (4) Thais tuberosa showed a strong preference for T. brunneus as prey. Food value, expressed as dry flesh weight, did not explain this preference. Capture rate of the preferred species T. brunneus fell to zero in water containing mucus released by T. niloticus.The results indicate that predation by T. tuberosa is more intense for T. brunneus than for T. niloticus and that a likely cause for this difference lies in the antipredator responses of the two prey species. The mucous response of T. niloticus appeared to be more effective for avoiding predation by T. tuberosa than was the flight response of T. brunneus.Journal of Zoology 05/2009; 241(1):145 - 159. · 2.04 Impact Factor
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ABSTRACT: Ocean acidification poses a range of threats to marine invertebrates; however, the potential effects of rising carbon dioxide (CO2) on marine invertebrate behaviour are largely unknown. Marine gastropod conch snails have a modified foot and operculum allowing them to leap backwards rapidly when faced with a predator, such as a venomous cone shell. Here, we show that projected near-future seawater CO2 levels (961 µatm) impair this escape behaviour during a predator-prey interaction. Elevated-CO2 halved the number of snails that jumped from the predator, increased their latency to jump and altered their escape trajectory. Physical ability to jump was not affected by elevated-CO2 indicating instead that decision-making was impaired. Antipredator behaviour was fully restored by treatment with gabazine, a GABA antagonist of some invertebrate nervous systems, indicating potential interference of neurotransmitter receptor function by elevated-CO2, as previously observed in marine fishes. Altered behaviour of marine invertebrates at projected future CO2 levels could have potentially far-reaching implications for marine ecosystems.Proceedings of the Royal Society B: Biological Sciences 01/2014; 281(1774):20132377. · 5.68 Impact Factor