Project number: 1995-048
Project Status:
Completed
Budget expenditure: $56,636.00
Principal Investigator: Chung Cheng Lu
Organisation: Melbourne Museum
Project start/end date: 29 Jun 1995 - 10 Jun 2004
Contact:
FRDC

Objectives

1. To produce a diagnostic illustrated key for identification of cephalopod beaks in the diets of marine vertebrates from southern Australian waters.
2. To analyse relationships between beak morphometrics and whole animal attributes, in order to develop back-calculation formulae for estimation of prey size and biomass.

Final report

ISBN: 0-7311-7253-1
Author: Chung Cheng Lu
Final Report • 2003-12-08 • 7.76 MB
1995-048-DLD.pdf

Summary

Squid, octopus and cuttlefish (cephalopods) are known to be an important food source for many marine animals including whales, porpoise, seals, seabirds, tuna, sharks and swordfish. The hard beaks (chitinous mandibles) of these preys are frequently encountered in predator stomachs. Cephalopod beaks can be used to identify the prey species and to calculate prey size and biomass consumed. Such hard parts from fishes (i.e. otoliths and vertebrae) have long been used for these purposes. Cephalopod species in the northern hemisphere have also had such tools available, but until now little information has been available on this aspect of the cephalopod fauna of our region.
 
A key of cephalopod beaks of 75 southern Australian species is available to identify samples taken from predators in this region for the first time, along with the formulae required to calculate prey size and biomass. 
Production of this key required the analysis of 1596 specimens, involving detailed measurements of various parts of the whole animal (mantle length, animal weight) and the beaks. Statistical analysis of the data then allowed the description of the relationship between beak measurements and the size and weight of animals, providing formulae to back calculate prey size and biomass.

A table provides details of the species examined, classified to order and family, with information on the size and weight range of whole animals. Most complete beaks can be easily identified to the order level and a key is provided for this. Further keys are provided to allow identification to genus/species level within each of the four orders. Detailed descriptions of beaks are provided for each species, supplemented by further tables providing ranges, ratios and means of various beak characters.

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