Alternative tactics and responses to conflicting inputs in the porcellanid crab Petrolisthes elongates

Abstract

When animals receive stimuli associated with incompatible responses, they either show behaviour patterns relevant to just one input (hierarchical model) or show levels of responses intermediate in intensity (summation model). When animals have alternative responses to one category of input, the summation model can be followed.

Individuals of the porcellanid crab Petrolisthes elongates were exposed to food odours and then to alarm odours and the intensity of feeding behaviours recorded. With their chelipeds intact, crabs exposed to food and alarm odours showed intermediate levels of feeding. Following the induction of cheliped autotomy (thereby eliminating autotomy as an alternative response to predation risk), the crabs exposed to food and alarm odours showed a complete cessation of feeding responses. Thus elimination of an alternative response to elevated predation risk led to a switch from the summation model to the hierarchical model, as predicted.

Keywords:

• Behaviour
• Porcellanid crab
• Chemosensory
• Food odour
• Alarm odour
• Summation model
• Petrolisthes elongates

Acknowledgments

This study was carried out while I was a Visiting Erskine Fellow at the University of Canterbury and that support is gratefully acknowledged. I would like to thank Catherine Bach and Colin McLay for their comments on the article.

Notes

E-mail: [email protected]

Additional information

Notes on contributors

Brian A. Hazlett *

E-mail: [email protected]