Australia's argonauts ("paper nautiluses"): taxonomy, biology and a revision of the family Argonautidae (Mollusca: Cephalopoda)

A project undertaken at the Science Department, Museum Victoria, and supervised by Mark Norman

Argonauts (family Argonautidae) are a unique group of pelagic octopuses found in the tropical and temperate waters of the world. These animals are best known by the beautiful brittle white shell of the female (often called a "paper nautilus"), which is highly prized by beachcombers. Less well-known are the miniature shell-less males. Despite literature and speculation dating back to Aristotle, there is still little known of the hidden lives of the argonauts.

Rare glimpses of argonauts paint a picture of a bizarre pelagic creature. These include reports of huge schools of females covering the ocean surface, rapid shell reconstructions, using jellyfishes for transport and defence, extreme size dimorphism between the sexes, and severed male body parts living within the female's gill cavities. Mass shore strandings periodically occur, some covering beaches up to 2 metres thick!

To date, the world's species have been identified solely on the basis of the females' shells, with each slight variant being assigned a new species name. As a consequence the taxonomy is a mess. In contrast, males are minute and completely lack a shell. No previous study has made a comprehensive attempt to define the composition of the living argonaut fauna, describe the biology and behaviour of these ocean travellers, nor understand their distributions and origins. Australian waters are home to the highest diversity of these animals of any country in the world. Shells of these animals are well represented in museum and private collections. Less common are specimens of the actual animals that made and resided within these shells.

The general aim of this study is to resolve the identities of the Australian and world fauna, and seek insights into their hidden lives.

Specific objectives:
  • Determine and describe the Australian argonaut fauna.
  • Resolve the taxonomic status of purported species worldwide, based on morphological and molecular data
  • Synthesise and validate worldwide distribution records to investigate the biogeography of the family
  • Investigate the extreme reproductive strategy of argonauts.
  • Provide the opportunity for training a young taxonomist with experienced taxonomists both in Australia and overseas.

For further information on the project contact:

Dr Mark Norman (mnorman@museum.vic.gov.au) or Julian Finn (jfinn@museum.vic.gov.au).

 
Figure 1. Living argonaut female.

Figure 2. Shells of females of three different argonaut species.