Next family introduction >
The Ellobiidae is a family of air-breathing molluscs found mainly in the high intertidal zone of mangrove swamps and salt marshes. Ellobiids are distributed world-wide, with a concentration of species in the Indo-West Pacific Ocean. There are 36 species recorded from Australia, mostly from northern Australia, and 13 species from NSW. The NSW representatives, as with many families, consist of tropical Indo-West Pacific species occurring in the north of the state, and southern Australia species in the south. Included in the 13 NSW species are two Indo-West Pacific species newly recorded from NSW, from just south of the NSW-Qld border, by Denis Riek. One species found in NSW, Myosotella myosotis, was introduced from Europe and is now widespread.
Ellobiids generally have barriers in the aperture of the shell, ranging from a few simple folds on the columella to a much narrowed aperture with strong denticles on both lips that nearly close the aperture. The shells may be smooth or strongly sculptured. The colour of the shell is generally brown, often with a few pale bands, although a few species are paler coloured. In size they range from 3 to 100 mm in length, but NSW species are less than 25 mm.
Ellobiids are air-breathing animals, so live in the upper part of the intertidal zone where they are exposed to the air for at least part of the time. In the tropics a few species have abandoned the marine environment altogether and become fully terrestrial, but all of the NSW species are at some time submerged by the sea. The animals are hermaphroditic; some are consecutive hermaphrodites, changing from male to female, and a few, such as Melampus, are simultaneous hermaphrodites, producing eggs and sperm simultaneously.
Their habitat is in mangroves and saltmarshes. In mangroves they live in the high intertidal zone on mud or wood or amongst clumps of oysters. In NSW they have also been found in cracks or holes on the underside of wood pressed into the mud. In saltmarshes they occur at mid- to high-intertidal level, secreted under debris - even plastic bags!
The family in NSW is well documented in terms of species present, but their distribution and exact habitat is poorly known. There is no consolidated reference to the family in Australia or in the Indo-West Pacific. An excellent treatment for the species found in northern NSW is given by Denis Riek at http://www.roboastra.com/index.html.
Riek, D. 2016. Seaslugs and other marine invertebrates of the Tweed-Byron coast, Australia. http://www.roboastra.com/index.html. Galleries: Prosobranchia 5 and Mangroves + Sandflats 2. (Accessed 19 February 2018).
All the known species from NSW are covered here.
Ellobiids shell are easy to place into the family, because of their high intertidal habitat and distinctive elaboration of teeth, folds and denticles in the aperture.
Copyright Des Beechey 8 June 2018