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Aplysia parvula (Family Aplysiidae)

Little Sea Hare

Distribution:

The Little Sea Hare has been recorded from many locations around the world. It is found in both tropical and temperate seas. It is not found in the north-west Atlantic Ocean. It occurs all around Australia and has been recorded in NSW, Vic, Tas, SA, WA and NT. It is very widespread (NSW, VIC, TAS, SA, WA, NT).

Features:

The Little Sea Hare is the smallest sea hare from Australian waters. Its body is small, slender, with slightly swollen body mass. It has a long, well-rounded tail. It grows to a length of 100 mm. The foot mass, called the parapodium is large. It has a small, dark brown, shield-like, horny shell that is visible through a wide gap in the top of the mantle. Its lower tentacles extend out to the front, while the rhinophores (chemical detectors) are positioned on the top part of the head.

The colour of the Little Sea Hare is quite varied. It depends upon the algae on which it is feeding. Often the colour may be dark reddish-brown to olive and light greenish-brown, speckled all over with white. Colours it has been recorded as being include red, brown, yellow and green. Its parapodia, tentacles and rhinophores are characteristically marked with black.

Ecology/Way of Life:

The Little Sea Hare occurs in rock pools at mid tide level and below to 20 metres. It is found under stones and on algae and seagrasses. It is also found on exposed reef. In the intertidal its preferred algae food seems to be Laurencia spp. where the animal is dark-brown, or Sea Lettuce, Ulva spp. where the animal is olive-brown in colour. Beneath the tides, the favoured algae are Plocamium spp. where the sea hare is coloured reddish-brown (Shepherd & Thomas, 1989). If it is disturbed it exudes a reddish purple ink from the opaline gland.

Interaction with Humans/Threats:

The Little Sea Hare is probably not under threat from human activities because it is so widespread and common from around Australia. However, like all other opisthobranchs, it can be sporadic in numbers. It may be common at some sites for months and then not be seen there again for years (Edgar, 1997).

Other Comments:

Aplysia parvula Morch, 1863. It has been recorded as Aplysia concava, Sowerby, 1822, and Aplysia norfolkensis, Sowerby, 1869.

Aplysia may come from two Latin words. A means without or not, while plysia may come from plicare, meaning a fold or a bend. Parvula comes from the Latin word parvus that means little. Together, this is the little sea hare that has a smooth surface, without folds.

Further Reading:

Edgar, G.J. (1997). Australian Marine Life: the plants and animals of temperate waters. p.272, Reed.

Macpherson, J. H. & Gabriel, C. J. (1962). Marine Molluscs of Victoria. p.247, Melbourne University Press.

Marine Research Group of Victoria (1984). Coastal Invertebrates of Victoria: An atlas of selected species. p.69, Museum of Victoria.

Shepherd, S. A. & Thomas, I. M. (1989). Marine Invertebrates of Southern Australia. Pt. II. p.745, South Australian Govt. Printing.

Acknowledgments:

Text, map & photograph by Keith Davey.

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