THE COST OF DRILLING IN THE COLD: CLIMATE CHANGE AND CANNIBALISM IN NATICID GASTROPODS FROM THE LA MESETA FORMATION AT SEYMOUR ISLAND, ANTARCTICA
We examined the record of cannibalistic drilling by the Eocene naticid Polinices subtenius from the La Meseta Formation of Seymour Island, Antarctica to assess the impact of a cooling climate on this mode of predation. As the climate cooled through the Eocene, cannibalistic drilling frequencies remained stable at around 5%, but an important behavioral aspect of cannibalism changed. Although the size structure of the Polinices population remained stable through time, the drilled individuals were on average over 30% smaller than they were before cooling began.
The observed pattern may be related to the propensity of naticids to select prey to maximize energy returns. The preferred prey size at a given temperature reflects a combination of prey-handling efficiency and feeding efficiency. P. subtenius may have adapted or acclimated to cooling temperatures by shifting to smaller, thinner prey, which would have been easier to drill in a colder environment.