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.
- [show abstract] [hide abstract]
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
- [show abstract] [hide abstract]
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
- [show abstract] [hide abstract]
ABSTRACT: Between November 1982 and August 1984 diving observations of two intertidal limpets' defensive behaviours in response to two predatory species were made near the Seto Marine Biological Laboratory of Kyoto University, in Wakayama Prefecture, Japan, for over 800 h. The focus of the observations was a simple isolated rock, 0.9 m2 in area with an inclination of 75. The pulmonate homing limpet Siphonaria sirius responded by fleeing from its home in response to the whelk Thais clavigera and by calmping tightly to its home scar in response to the starfish Coscinasterias acutispina. Both behaviours were successful for avoiding predation. After a whelk moved far away, limpets returned to their homes. The patellid limpet Cellana toreuma showed mantle folding behaviour or fled for an average distance of 8 cm vertically upwards in response to the whelk and for an average distance of 21 cm vertically upwards in response to the starfish. The amount of time predators spent foraging increased in the low intertidal zone relative to the mid and high zones, and most predator attacks were observed during the limpets' resting periods (submersion in late afternoon or nighttime). The upward directional flight displayed by C. toreuma was related to the upward orientation of the limpets' heads when they are in a resting position. Half of the limpets observed fleeing downward away from a starfish, a movement elicited by a downward attack, received a second attack. These limpets were preyed upon at the second encounter 67% of the time. The upward fleeing behaviour of C. toreuma resulted in the shifting of its resting site higher up the study site where fewer attacks occurred and where the mortality rate was at its lowest. It is suggested that the homing behaviour of S. sirius and the upward fleeing behaviour of C. toreuma are mechanisms by means of which interspecific competition between limpets is reduced and coexistence on a small rock surface is maintained.Marine Biology 05/1993; 116(2):277-289. · 2.47 Impact Factor