Post-mortem drift in Australian cuttlefish sepions: its effect on the interpretation of species ranges

ABSTRACT

Post-mortem drift is a common phenomenon within living shelled cephalopods (Nautilidae, Sepiidae and Spirulidae) and has led to the misinterpretation of geographical ranges in some species. In this study, the distributional ranges of reliably identified cuttlefish and beach-collected sepions (cuttlebones) from the Australian Museum, Museum Victoria and the Museum and Art Gallery of the Northern Territory collections were compared to determine the extent of sepion drift. In 12 of the 24 species examined, the distributions of dry sepions extended beyond the currently known ranges of the living populations as ascertained from the collection of intact animals. In some cases, this was in the order of hundreds of kilometres. These discrepancies are discussed in relation to the known depth ranges of each species, sepion morphology and oceanography. The results suggest that a cautionary approach should be taken in interpreting distributional data, particularly when using electronic databases that are likely to comprise sepion and whole animal locality information. Sepion distributions alone may be indicative of drift outside the true range of a species, or may suggest wider distributions of cuttlefish populations than are currently understood based on available information. Sepion drift is postulated to be the more likely explanation.

KEYWORDS:

• Australia
• currents
• cuttlefish distribution
• Sepiidae
• sepions

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Erratum

Acknowledgements

I would like to thank Professor Peter Ward and Professor C.C. Lu for introducing me to cephalopods. Thanks to Chris Rowley (MV) and Richard Willan (NTM) for providing access to their collections. I am very grateful to the two reviewers, Professor Pascal Neige and Dr Erik van Sebille for their comprehensive and constructive reviews which greatly improved this manuscript.

Disclosure statement

No potential conflict of interest was reported by the author.