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Patterns of drilling predation of cassid gastropods preying on echinoids from the Middle Miocene of Poland

100%

Zlotnik M., Ceranka T.

Acta Palaeontologica Polonica

2005

tom 50

nr 3

Test−drilling predation by cassid gastropods on minute clypeasteroid echinoids has been studied in the fossil assemblage of the Heterostegina Sands (middle Miocene, Holy Cross Mountains, Poland). The analysed prey, collected from two sublithofacies of the Heterostegina Sands (coarse−grained Heterostegina Sands and fine−grained Heterostegina Sands), represent three species of Echinocyamus (E. linearis, E. pusillus and E. pseudopusillus). The drill holes were produced presumably by one cassid species, Semicassis miolaevigata. The investigation showed that drilling predation intensities varied among the prey species. Within both fine− and coarse−grained sands, E. linearis was drilled more frequently than E. pusillus. An intermediate value of drilling predation was recognised for E. pseudopusillus. The intensities of drilling predation recognised for some of the prey species (E. pusillus) varied also between (but never within) the sublithofacies. Drilling predation was both size− and site−selective. Larger individuals of E. linearis and E. pusillus were attacked more frequently and the aboral side of the test of all Echinocyamus species was drilled preferentially. An extremely high concentration of drill holes was observed in the apical disc and petals. Results obtained for the most abundant prey (E. linearis) indicate that the predatory behaviour of large cassids was somewhat different from those typical of small cassids. Large cassids drilled and consumed their prey almost always individually, whereas small cassids sometimes preyed upon the urchins in a group. Large cassids displayed also a higher site−selectivity. They more frequently drilled in the petals and apical disc. The patterns of drilling predation were most likely controlled by the potential energetic value of prey (measured by the internal volume/test thickness ratio), prey and predator mobility, prey mode of life, thickness and porosity of the prey's tests, as well as by the proportions between the size of the prey and size of the predator. The results suggest that the mode of life of the prey and its test structure can influence the drill hole morphology.

Traces of cassid snails predation upon the echinoids from the Middle Miocene of Poland

100%

Ceranka T., Zlotnik M.

Acta Palaeontologica Polonica

2003

tom 48

nr 3

Drill holes on tests of Echinocyamus linearis from the Middle Miocene Korytnica Basin represent the first well documented fossil record of cassid predation from Poland. These traces complement the ecological information on the size and structure of cassid populations recorded by body fossils. The high number of drill holes recognised from the Heterostegina Sands, the uppermost part of the Korytnica depositional sequence, indicates the occurrence of a large cassid population during the late stage of development of the Korytnica Basin. The small size of most of the drill holes indicates that juvenile gastropods of the family Cassidae, which are not preserved in the fossil record of the investigated area, were also present in the cassid populations.

Ograniczanie wyników

2 Acta Palaeontologica Polonica

2 Ceranka T.

2 Zlotnik M.

1 2005

1 2003

Wyniki wyszukiwania

Patterns of drilling predation of cassid gastropods preying on echinoids from the Middle Miocene of Poland

Traces of cassid snails predation upon the echinoids from the Middle Miocene of Poland