Biodiversity

Australian Biological Resources Study

Species Bank Home

Thalotia conica (Family Trochidae)

Conical Top Shell, Hoop Top Shell

Distribution

Distribution:

The Conical Top Shell has a southern Australian distribution. It ranges from Wilsons Promontory, Vic across southern shores, including Tas and SA, and south-western Australia to Geraldton, WA. It seems to be uncommon in Victoria. (VIC, TAS, SA, WA)

Features:

The Conical Top Shell has a small shell that is solid and conical, with even, slightly rounded whorls. Its sides are almost straight. The protoconch at the tip of the shell is smooth and consists of 2.5 whorls. The shell grows to a length of 15-23 mm. The shell sculpture consists of granular or beaded, spiral ribs, 5-6 or more occur on the whorls, and 6 on the base. A slight keel divides the shells sides from its base. The aperture is small and squarish with a thick and sharp outer lip, marked with several nodules. Inside the aperture is marked with a concentric sculpture. The columella is straight, with a projecting base tooth and marked with several nodules. There is no umbilicus. Its operculum is round and consists of horn-like material.

The shell exterior is variable in colour, mostly it is reddish-brown to pink, or grey in colour with dark-brown flecked spiral ribs. The whitish axial lines form a tessellated or regularly chequered appearance. The shell apex or protoconch is red, crimson or pink. The shell interior is pearl-like.

Ecology/Way of Life:

The Conical Top Shell is mostly found in estuaries living on seagrasses of the genera Posidonia spp. and Amphibolis spp. that are usually covered with marine growths. It is a herbivore. On ocean shores it is found on algae that is growing in rock pools, or on seagrass and algae in sheltered areas. It occurs from low tide level to 25 metres depth.

Preferred Image

Interaction with Humans/Threats:

The Conical Top Shell has a wide distribution range across southern Australia and is common in south-western Australia. It is therefore most likely not under threat from human activities.

Other Comments:

Thalotia comes from the Greek word thalassa or thalatta, meaning the sea. Conica comes from the Greek word konos, meaning a cone or cone-shaped.

Further Reading:

Davey, K. (1998) A Photographic Guide to Seashore Life of Australia. p.87, New Holland Press, Sydney.

Edgar, G.J. (1997). Australian Marine Life: the plants and animals of temperate waters. p.239, Reed.

Jansen, P. (2000), Seashells of South-East Australia. p.22, Capricornia Publications.

Jones, D. and Morgan, G. (1994). A Field Guide to Crustaceans of Australian waters. Reed.

Macpherson, J. H. and Gabriel, C. J. (1962). Marine Molluscs of Victoria. p.67, Melbourne University Press.

Marine Research Group of Victoria (1984). Coastal Invertebrates of Victoria: An atlas of selected species.p.36, Museum of Victoria.

Shepherd, S. A. and Thomas, I. M. (1989). Marine Invertebrates of Southern Australia. Pt. II. p. 555, South Australian Govt. Printing.

Wells, F. E. and Bryce, C. W. (1988). Seashells of Western Australia. p.44, Western Australian Museum.

Wilson, B. (1993) Australian Marine Shells. Prosobranch gastropods. Odyssey Publishing.

Wilson, B. R. and Gillett, K. (1979). A Field Guide to Australian Shells: Prosobranch Gastropods. p.39, Reed.

Acknowledgments:

Text, map and photograph by Keith Davey.

Sponsorship welcomed:

Please Contact ABRS if you wish to discuss sponsoring this or other pages.


Images and Multi-media:  
Attached Image  
image/jpeg 33353 bytes Conical Top Shell
Distribution Map  
image/gif 998 bytes Distribution of Conical Top Shell

Return to Species Bank home

SpeciesBank

Key

   Links to another web site
   Opens a pop-up window