UNRAVELING THE MYSTERY OF REVERSE DRILL HOLES IN NEOGENE BIVALVES

Predatory common drill holes on a miocene Turritella terebralis Lamarck, 1799 from Leognan (France).

In a fascinating study, researchers have uncovered a unique predation behavior exhibited by gastropod predators on Neogene bivalves from the Netherlands. This behavior, termed "reverse drill holes," provides insight into the challenges predators face when distinguishing between live and dead prey. Here are the key points from the research:

·      Definition of Reverse Drill Holes: Reverse drill holes are unique in that they are created from the inner side of the bivalve's shell, indicating a predation attempt that did not effectively utilize the predator's sensory capabilities to differentiate between live and dead prey.

      (1–3) A valve of Astarte incerta Wood, 1850, fromthe lower Pliocene Oosterhout Formation of Langenboomin the Netherlands (MAB 4685) exhibiting a reverse naticid drill hole. Views: outer (1), inner (2), and detail (3). (4–6) A valve of Astarte goldfussi Hinsch, 1952, from the lower to middle Miocene Miste Bed (Aalten Member, Breda Formation) of Miste in the Netherlands (RGM.783230) exhibiting a reverse drill hole. Views: outer (4), inner (5), and detail (6) (From Klompmaker & Dietl, 2024)

·      Chemical Cues as a Trigger: The study proposes that chemical cues released by nearby living prey may have confused the gastropods, leading them to mistakenly drill into empty shells. This hypothesis suggests that the presence of these cues can significantly influence predator behavior.

·    Rarity of Reverse Drill Holes: The research found that reverse drill holes are quite rare, accounting for less than 1% of all drill holes observed in the studied assemblages. This contrasts with other forms of unsuccessful predation, such as incomplete drill holes and multiply-drilled specimens, which are more common.

·      First Fossil Evidence: This study marks the first documented instances of reverse gastropod drill holes in the fossil record, highlighting a previously unrecognized aspect of predator-prey interactions in ancient ecosystems.

·        Implications for Predator Behavior: The findings suggest that while predators generally have effective sensory and decision-making processes, there are instances where these processes can fail, leading to mistakes in prey selection. This has broader implications for understanding predator behavior and the evolutionary pressures that shape these interactions.

 

Common drilling holes in Anadara diluvii (Lamarck, 1805), a bivalve (clam) of the family Arcidae from the pliocene of Barcelona.

This research not only sheds light on the complexities of ancient predation but also emphasizes the importance of chemical communication in ecological interactions. The study opens new avenues for exploring how predators adapt their hunting strategies in response to environmental cues.

Reference: Klompmaker, A. A., & Dietl, G. P. (2024). Reverse drill holes: remarkable mistakes made by gastropod predators attacking Neogene bivalve prey. Journal of Paleontology, 1–7. doi:10.1017/jpa.2024.36