DRILL HOLE IN FRESHWATER GASTROPODS FROM THE PLEISTOCENE OF THE SOUTHEASTERN SPAIN: EVIDENCE FOR DRILLING PREDATION (OR PARASITISM) IN FRESHWATER ECOSYSTEMS?

KOWALEWSKI, Michal¹, DOMENECH, Rosa², MARTINELL, Jordi² and MANCHENO, Miguel-Angel³, (1)Florida Museum of Natural History, University of Florida, 1659 Museum Road, PO Box 117800, Gainesville, FL 32611, (2)Facultat de Geologia, Universitat de Barcelona, Marti i Franques s/n, Barcelona, 08028, Spain, (3)Departamento de Quimica Agricola, Geologia y Edafologia, Universidad de Murcia, Campus Espinardo, Murcia, 30100, Spain, rosa.domenech@ub.edu

Predators and parasites that drill in shells and tests of their prey/host are widespread in modern marine ecosystems. These diverse drillers include several unrelated groups of invertebrates (mostly within gastropods). Drilling is also well documented in the marine fossil record. However, reports of drillings in freshwater settings (recent or fossil) are virtually lacking. Here, we report drillings in freshwater gastropods from the Pleistocene of Spain.

A total of 28 samples of freshwater gastropod shells were collected from a Pleistocene locality of Mula (Murcia Province, SE Spain). All samples represent a low-diversity association dominated by Melanopsis sp. and Theodoxus sp. The additional two species (Corbicula sp. and Melanoides sp.) are also present in most samples, but in low abundance. For pooled data (43,116 specimens total), Melanopsis sp. represents 49% specimens, Theodoxus sp. 44%, Corbicula sp. 4% and Melanoides sp. 3%, respectively.

A total of 1389 specimens (3.2%) contained round, circular drill holes with smooth margins. Usually, only one drill hole is observed per shell. Holes penetrate only one shell wall and are typically located on the apertural whorl. The distribution of holes across taxa is highly non-random. Nearly all drilled specimens (1379 out of 1389) belong to Melanopsis sp., whereas drill holes are completely absent in the equally abundant Theodoxus sp. In addition, 10 drilled specimens of Corbicula sp. were recorded in one sample.

The morphology of drill holes, presence of one hole per shell only, preferential site of drilling, and highly non-random distribution of drill holes across species, suggest consistently that drill holes represent biotic interactions between an unknown freshwater driller and gastropod prey/host. The frequent drill holes in the Pleistocene freshwater gastropods of SE Spain suggest that predatory (or parasitic) drillers may also be present in some non-marine ecosystems.

Session No. 96--Booth# 24

Paleontology: Behavior & Function (Posters)

Monday, 19 October 2009: 9:00 AM-6:00 PM

Hall A (Oregon Convention Center)

Geological Society of America Abstracts with Programs. Vol. 41, No. 7, p.265

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2009 Portland GSA Annual Meeting (18-21 October 2009)

DRILL HOLE IN FRESHWATER GASTROPODS FROM THE PLEISTOCENE OF THE SOUTHEASTERN SPAIN: EVIDENCE FOR DRILLING PREDATION (OR PARASITISM) IN FRESHWATER ECOSYSTEMS?