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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.

Size-related changes in predatory behaviour of naticid gastropods from the Middle Miocene Korytnica Clays, Poland

88%

Zlotnik M.

Acta Palaeontologica Polonica

2001

tom 46

nr 1

The analysis of shell-drilling predation by naticid gastropods on molluscs from the Korytnica Clays (Middle Miocene, Holy Cross Mountains, Central Poland) has focused on the bivalve Corbula gibba and gastropods Natica tigrina and Hinia restitutiana. The results indicate that predatory behaviour of naticids varies depending on the size of the predator. When drilling corbulids, large naticids displayed higher site-selectivity than smaller naticids. Also, large naticids drilled energetically attractive prey (Hinia restitutiana and Natica tigrina) more frequently than small naticids. Preferential drilling displayed by large naticids from the Korytnica Clays increases the net energy gain for the predator and in result allows it to drill more effectively.

Ograniczanie wyników

2 Acta Palaeontologica Polonica

2 Zlotnik M.

1 Ceranka T.

1 2005

1 2001

Wyniki wyszukiwania

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

Size-related changes in predatory behaviour of naticid gastropods from the Middle Miocene Korytnica Clays, Poland