This web site is an expanding reference to the marine shelled molluscs of NSW. New families are added occasionally; eventually it will include all families of marine molluscs that occur in the state. The scope is molluscs that occur from below high tide to abyssal depths. It does not include families found only on land or in fresh water.

Species are arranged in scientific order by family. The genus and species name used is from the latest revision of the group, obtained from the scientific literature, or from the collections of the Australian Museum.


For each family, the introduction to the family details the coverage. For the families of large shells, all species known from NSW are described in detail and a photograph of each is provided. For some other families, the larger species are treated in detail and the remainder listed, with their distribution. For families where the state of taxonomic knowledge is poor, only a representative sample of the family is given.

Organisation of the Pages

The page for each species includes the following headings:

Description. This describes the species using terminology defined in the glossary, concentrating on features that differentiate this from other species. Where a range of colour, sculpture or shape exists this is usually noted.

Size: Gives the maximum, and if applicable, a typical adult size for the species, from the collections of the Australian Museum and of the author, or rarely, from the literature.

Molluscs grow from microscopic larvae, depositing the shell at the growing or outer edge. Some species modify the shape of the shell when they mature, normally by thickening the outer lip, but in the case of the cowries, by extending the outer lip so that it almost closes the aperture. In these forms it is possible to tell when the shell has finished growing, but in species where there is no such modification of the shell at maturity, it is not possible to tell if the shell has finished growing or not.

There is sometimes a wide range in the adult size of specimens within a species. Within one population most specimens will be around the average size for the population, with extremely small or extremely large individuals being rare.. There is often considerable variation in average size between populations.

For those families which have been extensively collected by shell collectors, the size data is skewed because collectors give undue emphasis to unusually large or small specimens (as well as uncommon colour forms or sometimes to deformities). This is particularly so with the much collected Cypraeidae, where the maximum size recorded in the literature is two or three times the typical size.

Distribution: The entire distribution is noted, as well as the distribution in Australia.. Australian distributions are given clockwise around the Australian coast, so Cape Moreton to south-western WA is a southern Australian distribution.

The NSW mollusc fauna is a combination of two distinct faunas - the Indo-West Pacific and Southern Australian faunas. Northern Australia, including Queensland and the Great Barrier Reef, is part of the vast Indo-West Pacific faunal region, which extends from East Africa through South-East Asia into the central Pacific. Many species which occur in northern Australia are distributed widely throughout this zone. It has a high level of species diversity, with many of the species being large and brightly coloured. The Southern Australian zone by contract has a different evolutionary origin, with about 95% of its species endemic. It is far less rich in species, and with shells having less spectacular colouration.

The political borders of the state almost exactly mark the limits of overlap of the two faunas; the northern limit of the southern fauna is Cape Moreton at the NSW-Queensland border, and the southern limit of the northern fauna is Cape Howe at the NSW-Victoria border. In the overlap zone there is a gradual replacement of one fauna with the other, with the addition of some endemic species. Distribution of animals of the northern fauna that have long-lived pelagic larvae is achieved by the East Australian Current, a flow of warm water which commences in the equatorial region and continues to about Newcastle, whence it turns seaward. The West Wind Drift which flows along the southern Australian coast passes through Bass Strait, and sometimes extends northward up the southern coast of NSW, distributing larvae of the southern Fauna.

The same qualifications apply to reported ranges of popularly collected families as do to size ranges. Over two hundred years of collecting the range of tropical cowries has been extended well into NSW, but usually by only a handful of specimens in museum collections. For all families, apart from the dozen most collected families, our knowledge of ranges is quite patchy, and is not difficult to extend the reported range by intensive collecting.

Habitat: A general statement of habitat is give, such as rocky shore, or estuarine mud flats. Although we have a good broad understanding of what lives where from observation and collection, our knowledge of why animals live there, and the details of their interaction with their habitat, is generally poor in detail. Distributions sub-tidally are particularly poorly known.

With habitat, an estimation of the rarity is given. These ratings have the following meanings, for an experienced collector collecting living animals intertidally, or sifting through beach washup.

  • Abundant:  You can't help seeing them when you look in the right place.

  • Common: A 10 minute search in the right place will find a few

  • Moderately common:  A 10 minute search in the right place will probably find one

  • Uncommon: You will probably find one with an hours searching

  • Rare: You might never find one.

Comparison: A comparison is given with closely related or similar species.

Synonyms: Generally, only synonyms from the Australian literature are given. However, all names are given that appear in  A Reference List of the Marine Mollusca of New South Wales (Iredale & McMichael, 1962).

This work presents the state of knowledge of the NSW marine molluscs as it is now. That state has been continually advancing since scientific investigation of the fauna began with exploration over three hundred years ago, and will continue to advance, probably at an accelerating pace. It is expected, and hoped, that this work will become out of date with advancing knowledge, but it is hoped that in the meantime it provides a useful reference and a stimulus for investigation. There are no doubt errors and omissions, which the author is keen to know about.