Escape responses of 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.
- SourceAvailable from: Scott M. Fitzpatrick
[Show abstract] [Hide abstract]
- "Additionally, fishing appears to decline over the last 1500 years at the site so, while a greater proportion of potential S. gibberulus predators are being fished, fewer fish overall are being caught, complicating a straightforward correlation between these variables. The Chelechol ra Orrak shellfish assemblage has not yet been fully quantified, thus it remains to be seen whether humped conch size changes correspond to increasing exploitation of invertebrate predators such as crabs or molluscs like the voracious predatory Conus snails (Chase, 2002; John and Waters, 1966). It is worth noting that S. gibberulus size increase in the Middle period, does roughly coincide with a general shift to more intensified agricultural productivity in Palau and later movement from inland villages to coastal stonework villages around ca. 1200e700 BP when agriculture became paramount, a time referred to as the " Transitional era " (Liston, 2009; Liston and Tuggle, 2006; Wickler, 2002). "
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; DOI:10.1016/j.jas.2010.06.013 · 2.20 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: The escape response of Strombus maculatus is described in detail, including the apparent adaptive morphology of the foot, operculum, and eyestalks. The response is elicited by a chemical stimulus from two molluscivorous species of Conus and two gastropod-eating species of Cymatium but not from other predatory species of these genera. Strombus habituated within three trials to a solution of "factor" from Conus pennaceus, but habituated only rarely, and then only after many trials, to contact with the live Conus. It was concluded that the eyes of S. maculatus are not used to see the Conus; however, eye removal significantly disrupted the orientation of the escape response, suggesting that the animal monitors some environmental cue such as polarized light. Tentacle removal appeared to interfere with escape response orientation but only to a variable extent.
- [Show abstract] [Hide abstract]
ABSTRACT: Qualitative comparisons of the predator-induced defensive behaviors of four species of trochid gastropod, Margarites pupillus, M. salmoneus, M. rhodia, and Calliostoma ligatum, under controlled laboratory conditions indicate that the degree and strength of the response varies according to the sensory information received from a predator and according to the species of predatory seastar or gastropod inducing the response. Generally, all four species of gastropod demonstrate a weak to moderate avoidance response to the scent of such predatory seastars as Leptasterias hexactis and Pisaster ochraceus; whereas direct contact with their soft parts elicits strong and often violent defensive behaviors characterized by shell twisting, propodial rearing which often leads to a loss of contact with the substrate, and somersaulting by metapodial thrusting. It is hypothesized that the inversion of the shell induced by direct contact with a predator sets up the metapodial thrusting behavior and also part of the righting repertoire, which facilitates more rapid flight from the predator. Margarites spp. respond to the scent and contact with the dire whelk, Searlesia dira; whereas Calliostoma is unresponsive to the snail, but more responsive to the scent and contact of the sunstar Pycnopodia helianthoides than are the other species of gastropods studied.