GASTROPOD DRILLING PREDATION IN THE UPPER JURASSIC OF KUTCH, INDIA

ABSTRACT Gastropod drillholes on prey shells provide an opportunity to test the importance of predation in an evolutionary context. Although records of drilling predation are widespread across the Phanerozoic, the temporal distribution and relative importance of this mode of predation is still controversial. Further, some studies indicate a decline of drilling predation in the Mesozoic but other studies do not. In this study, we present a new dataset of gastropod drilling predation on Kimmeridgian and Tithonian bivalves of Kutch, India. Our study suggests that drilling was one of the prevailing modes of predation in the Upper Jurassic of Kutch with strongly variable intensities, ranging from 2% in the Kimmeridgian Seebachia to 26% in the Tithonian Pinna. A significant, albeit small, increase in drilling intensity from the Kimmeridgian to the Tithonian assemblages is associated with a change in relative sea-level and depositional environment. The morphology of drillholes and recent discovery of body fossils from the same stratigraphic units suggest naticid gastropods as the most likely drillers. A literature survey, along with previously collected specimen from the Jurassic of Kutch, reveals a more complex history of drilling predation than previously assumed.

High biogeographic and latitudinal variability in gastropod drilling predation on molluscs along the eastern Indian coast: Implications on the history of fossil record of drillholes

Studies on the large-scale latitudinal patterns of gastropod drilling predation reveal that predation pressure may decrease or increase with increasing latitude, or even show no trend, questioning the generality of any large-scale latitudinal or biogeographic pattern. Here, we analyze the nature of spatio-environmental and latitudinal variation in gastropod drilling along the Indian eastern coast by using 76 samples collected from 39 locations, covering ~2500 km, incorporating several ecoregions, and ~15° latitudinal extents. We find no environmental or latitudinal gradient. In fact, drilling intensity varies highly within the same latitudinal bin, or oceanic sub-basins, or even the same ecoregions. Moreover, different ecoregions with their distinctive biotic and abiotic environmental variables show similar predation intensities. However, one pattern is prevalent: some small infaunal prey taxa, living in the sandy-muddy substrate—which are preferred by the naticid gastropods—are always attacked more frequently over others, indicating taxon and size selectivity by the predators. The result suggests that the biotic and abiotic factors, known to influence drilling predation, determine only the local predation pattern. In the present case, the nature of substrate and prey composition determines the local predation intensity: soft substrate habitats host dominantly small, infaunal prey. Since the degree of spatial variability in drilling intensity within any time bin can be extremely high, sometimes greater than the variability across consecutive time bins, temporal patterns in drilling predation can never be interpreted without having detailed knowledge of the nature of this spatial variability within a time bin.

Drilling predation on Antarctic tusk shells: first records on Recent scaphopods from the Southern Hemisphere

Drillholes on shells are one of the few predation marks preserved in fossil molluscs, providing an opportunity to study and quantify predator-prey interactions in the palaeontological record. Among these, reports of drilling predation on scaphopods are rare, and such information from Antarctica is non-existent. We describe the finding of drillholes on scaphopods recovered from Recent mollusc assemblages between depths of 246.5 and 454.0 m in West Antarctica. The predation traces located in the middle sectors of two preyed shells belonging to Siphonodentalium dalli and Dentalium majorinum are identified as Oichnus and are interpreted as produced by naticids, probably Pseudamauropsis aureolutea. These new records constitute the first reports of drilling predation on scaphopods in Antarctica and also for Recent scaphopods of the Southern Hemisphere.

Evidence of non-drilling predation by a naticid gastropod in bivalves on Camocim Beach, Ceará, northeastern Brazil

Marine gastropods of the family Naticidae are worldwide distributed and known for their unusual predatory habits. Due to their wide distribution, the naticids are worldwide studied and known like predators of intertidal bivalves. The present study demonstrates the predation of the naticid gastropod Natica marochiensis on the bivalve Donax striatus in the northeastern region of Brazil.

Paleoecology of naticid–molluscan prey interaction during the Late Jurassic (Oxfordian) in Kutch, India: evolutionary implications

We document and quantify one of the oldest predator–prey interactions between naticid gastropods and molluscan prey, on the basis of drill holes in shells, from the Late Jurassic (Oxfordian) beds of Kutch, western India. Previously, many workers recorded naticid-like drill holes on prey taxa from the Triassic and the Jurassic, but in the absence of associated naticid body fossils, they remained equivocal. The present gastropod community is dominated by turritellines (98% of the sample) that form the turritelline-dominated assemblage, and the naticid drilling predation is restricted almost entirely to turritellines among gastropods. Confamilial naticid predation takes place occasionally. Within the bivalve community, corbulids and nuculids are most abundant and are drilled more often than other taxa. These observations indicate that prey selection was opportunistic and based solely on availability. Drilling intensities at both assemblage and lower taxon levels are low. Behavioral stereotypy of naticid predation in some cases is moderately high. Turritellines are often the preferred prey of naticid gastropods since the late Early Cretaceous. These two groups form a recurrent association reflecting prey–predator interaction. Here we suggest that both turritellines and naticids evolved during the Jurassic, and the prey–predator interaction between them was established shortly thereafter. Among bivalves, corbulids also became important prey of naticids in the same spatiotemporal framework. Corbulids are older than naticids and first appeared during the Middle Jurassic. After their first encounter with naticids, corbulids evolved conchiolin layers within the valves to resist predation.

An asynchronous Mesozoic marine revolution: the Cenozoic intensification of predation on echinoids

Predation traces found on fossilized prey remains can be used to quantify the evolutionary history of biotic interactions. Fossil mollusc shells bearing these types of traces provided key evidence for the rise of predation during the Mesozoic marine revolution (MMR), an event thought to have reorganized global marine ecosystems. However, predation pressure on prey groups other than molluscs has not been explored adequately. Consequently, the ubiquity, tempo and synchronicity of the MMR cannot be thoroughly assessed. Here, we expand the evolutionary record of biotic interactions by compiling and analysing a new comprehensively collected database on drilling predation in Meso-Cenozoic echinoids. Trends in drilling frequency reveal an Eocene rise in drilling predation that postdated echinoid infaunalization and the rise in mollusc-targeted drilling (an iconic MMR event) by approximately 100 Myr. The temporal lag between echinoid infaunalization and the rise in drilling frequencies suggests that the Eocene upsurge in predation did not elicit a coevolutionary or escalatory response. This is consistent with rarity of fossil samples that record high frequency of drilling predation and scarcity of fossil prey recording failed predation events. These results suggest that predation intensification associated with the MMR was asynchronous across marine invertebrate taxa and represented a long and complex process that consisted of multiple uncoordinated steps probably with variable coevolutionary responses.

Naticid drilling predation from tidal flats in northern Patagonia, SW Atlantic

Naticids and muricids are the main drilling gastropod families that leave a characteristic hole in their shelled prey. Drilling predation can be evaluated along spatial scales, and different latitudinal patterns (equatorward, poleward, mid-latitude peaks or no trend at all) have already been described. For Argentine Patagonia, most studies have analysed muricid predation, but scant information is available on naticid predation. This study provides evidence of predation by the moon snail Notocochlis isabelleana on a thin and fragile burrowing bivalve, Darina solenoides, along the intertidal sandflats at Pozo Salado, San Matías Gulf, in northern Patagonia. To estimate the incidence of predation, articulated specimens of Darina solenoides (N = 432) were randomly collected in the intertidal zone. Drill holes (N = 94) were recorded in shell lengths ranging between 10 and 35 mm. Taking into account previous studies in the region, the intensity of mortality by drilling (22%) constitutes a higher value than expected for this latitude. These results may help explain local patterns in a particular site in northern Patagonia which has been previously identified as an outlier, but further studies aimed at evaluating macrogeographic patterns are necessary for a better understanding of the regional factors that might be governing these predator–prey interactions.

Barnacle encrustation on molluscan prey offers associational resistance against drilling predation

Predation is one of the driving forces that shaped the marine ecosystems through time. Apart from the anti-predatory strategies adopted by the prey, the predatory outcome is often indirectly influenced by the other members of the ecological community. Association between organisms are often found to influence the outcome and the evolution of such association may have been guided by such interactions. Mollusc-burnacle association, although common, is not explored to assess if the epibiont offers the molluscs any protection against predation (associational resistance) or increases the risk by attracting predators (shared doom). Using a series of controlled experiments with a drilling predator (Paratectonatica tigrina), its prey (Pirenella cingulata) and an epibiont (Amphibalanus amphitrite), we evaluated the effect of epibionts on the drilling behavior of the predator by documenting the successful attack (Drilling frequency, DF), and handling time. Our results show that the prey with epibionts are significantly less likely to be drilled when the predator has sufficient choice of prey, consistent with the tenets of the associational resistance. The preference of choosing the non-encrusted prey, however, diminishes with fewer available prey. The handling time is significantly higher in the attacks on the encrusted prey than non-encrusted prey, even though the barnacles are not drilled. Although the proximity of the drilling site to encrustation tends to increase the handling time, the size of encrustation does not have any effect. Because the profitability of prey largely depends on the ratio of handling time and the energetic yield from consuming the prey, the increase in handling time due to encrustation makes it less profitable for the predator. The role of encrustation as a deterrent to predation might also explain the complex shell architecture in some prey gastropods that increases the likelihood of encrustation besides providing direct resistance against predation.