Scientific investigations on Baler shells
Article | Updated 7 months ago
The Western Australian Museum is performing research on Baler shells to determine how many different species occur in our waters and to better understand their distribution around the country.
The Baler shell is a large marine mollusc that belongs to the gastropod family Volutidae (volute shells). Of the 200 species of volutes distributed worldwide, around 70 are known from Australia. Many of those from Western Australian are endemic, found nowhere else in the world.
The spiral-coiled shell of Baler shells can finish with a rounded, knob-like end, and can reach over 45cm. The name “Baler shell” was given by European settlers because Aboriginal people were using this huge shell as a scoop to bail out their boats and canoes. The Baler shell was also used by native people to store water. The smooth and cream-coloured surface, adorned with attractive orange-brown patterns, makes the Baler shell a prized addition to shell collections. Some species have a lovely zebra pattern on the animal’s enormous foot, which evokes an Aboriginal painting.
Eating and Breeding
Baler shells are carnivorous and feed on other molluscs such as scallops, turban shells, tritons and even other volutes. To catch prey, the Baler shell seizes it with its large foot and plugs the prey’s aperture, essentially smothering it. They are generally nocturnal animals, crawling along the sea floor to find food, and burying themselves in the sand by day.
For breeding, Baler shells lay a first layer of eggs onto a rock or another shell and then stack more eggs on top, layer by layer, to form a case. The egg-case is hollow through the middle and has holes all through it, enabling the water flow to penetrate and ensure circulation around the eggs. An egg-case can contain more than 100 juveniles.
Australian Baler Shells
The Australian coastline houses four known species of Baler shells, from the intertidal zone down to 100 metres. The Northern Baler shell (Melo amphora), is distributed in the northern half of Australia, from the Houtman Abrolhos Islands to Queensland through the Northern territory coast. The Southern Baler shell (Melo miltonis) occurs from the Houtman Abrolhos to the South of the country. Melo umbilicatus is found all along the Queensland coast whereas Melo georginae occurs only on the eastern coast of Queensland.
Like other living volutes, all Melo are direct developers, which means that juveniles hatch directly from the egg mass and ‘crawl away’, without a free-swimming larval stage. This leads to a low dispersal potential and the possibility that populations will be isolated from each other. As well as broad genetic investigations on the Volutidae, the Western Australian Museum is undertaking molecular work to understand relationship among Melo species and elucidate distributional limits.
During a survey in the Kimberley region, Dr Clay Bryce found a Melo amphora, the northern Baler shell, and gives us some explanations about this species.
Explore our Volute collection through a behind-the-scenes photo gallery.