Marvellous Molluscs – Part 2

Dr John Healy is Curator of Molluscs at Queensland Museum and is actively involved with research on molluscs (malacology).

Dr John Healy

As John notes, the role of Curator of Molluscs covers many and varied activities. This includes taxonomic work on the collections, field work, identification of samples, public inquiries and even work on cultural and historical aspects of shell use and art through the ages. John has been extensively involved in taxonomic work on Australian Molluscs, and has named over 80 species new to science, including numerous bivalves and tusk shells.

John is currently researching the reproduction, cell ultrastructure, and evolution of bivalve (2-shelled) molluscs as part of the large international collaborative assembling the Tree of Life Project. John is an expert in the spermatozoan ultrastructure of bivalves such as the Giant Clam, oysters, mussels and marine snails. Reproductive tissue samples from a large range of bivalves (containing mature spermatozoa) are analysed with a SEM (Scanning Electron Microscope) and TEM (Transmission Electron Microscope) and many photographs are taken to reveal the full structure of the cells. His information will feed into the project once all the various samples have been analysed. The ultimate aim will be a fresh perspective on how bivalve molluscs evolved and how the living groups relate to each other.

Volute, Cymbiola pulchra

In association with the Dr Nerida Wilson of the Australian Museum, John is also working on the evolutionary relationships and classification of volute snails – a family of marine molluscs that has no planktonic stage in their life cycle. (The eggs of many other marine molluscs hatch into a planktonic stage that can move with the currents and establish the species in other areas.) Volutes are direct developers and as such are vulnerable to local extinctions if they are over-collected or if their habitat is substantially damaged. There are few individuals from other areas than can come in and re-colonise the area.

Beautiful bivalve, Spondylus versicolor

Many molluscs are named by the structure and colour of their shell alone, especially if the shell is distinctive enough. John notes that this can give rise to a bit of a dilemma: some species may be named but they could in fact be extinct. There have been some species of molluscs discovered and named in the recent past, for which no living specimen has ever been seen – only their shell! 

Argonaut ‘shells’ are occasionally washed ashore in their hundreds and thousands along the Tasmanian, Victorian and New South Wales coasts but are more unusual along the Queensland coastline. They are produced by female Argonaut octopuses, partly for their own protection, and eventually as a cradle for the protection of fertilised eggs. The female makes the ‘shell’ using two modified tentacles that she holds together like a mould. This is a wonderful adaptation that protects the eggs during their development. The male in contrast to the female, is tiny and rarely seen.  

Argonaut ‘Shell’ Case

The Argonaut ‘shell’ looks a little bit like a fossil ammonite – John draws attention to some similarities to true shells of the ammonite genus Scaphites – and some scientists believe that octopods may even be ammonites. However, the differences in shell structure are profound, suggesting the Argonaut ‘shell’ has developed independently of the chambered ammonite (and nautilus) true shells.

 To learn more about the marvellous world of Molluscs, visit the Mollusc page of our QM website.

 To learn more about the work that John does, visit his Biography page.

 To learn more about animal adaptations, view our Animal Adaptation Videos.

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About Adriana Bauer

I am a Senior Project Officer (Biodiversity) in the Strategic Learning section of the Queensland Museum. I have been working here since August 2008 but before then, I was teaching in secondary schools in Brisbane. My subject areas include Biology, Junior Science, and Junior and Senior Mathematics. Since working at the museum, I have been involved in developing online learning resources, QM Loans kits, updating our Inquiry Centre Fact Sheets, delivering professional development for teachers, and writing educational resources that support the new Australian Science Curriculum. I have a passion and interest in biodiversity and did my academic studies at the University of Queensland where I obtained a B.Sc, B.A, and Dip. Ed.
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