Triangular astarte (Goodallia triangularis)

Distribution data supplied by the Ocean Biodiversity Information System (OBIS). To interrogate UK data visit the NBN Atlas.Map Help



A bivalve with a triangular shell up to 0.3 cm in length. Both valves are similar in size and shape. The beak is just behind the mid-line, pointing inwards and slightly forwards, so the shell is slightly asymmetrical. The inner and outer surfaces are white but the outside of the shell has a layer of yellowish to brown (periostracum). The outer surface bears fine concentric lines that are closely spaced. The shell can be thick or thin resulting in a variable hinge line width. In adult specimens, the inner margin is crenulate or smooth but in juveniles, it is always smooth.

Recorded distribution in Britain and Ireland

Widespread around the coasts of Britain, but less common along the east coast of Scotland and western coast of Ireland.

Global distribution

Goodallia triangularis is distributed south to the Iberian Peninsula, into the Mediterranean and along the Atlantic coast of Morocco.


Goodallia triangularis inhabits sandy mud, sandy gravel and shell-gravel offshore to about 600 m.

Depth range

Offshore to about 600 m

Identifying features

  • Triangular in outline.
  • Greatest dimension along its dorsoventral axis but shell rarely exceeds 3 mm in length.
  • Both valves of the shell are similar in size and shape (equivalve).
  • Beak is just behind the mid-line, directed inwards and slightly forwards (inequilateral).
  • Shell bears fine, closely-spaced concentric lines.
  • The periostracum is yellowish to brown.
  • Both the right valve and left valve have two cardinal teeth.

Additional information

Goodallia triangularis is similar to Goodallia macandrewi, Goodallia micalii, and Goodallia pusilla but has a larger and more equilateral shell. Juveniles are similar in size to Goodallia gofasi but the inner margin is never crenulated, unlike Goodallia gofasi. Originally referred to as Astarte triangularis but differs from Astarte species by the shape of its gills (having only one inner demibranch).

Listed by

- none -


  1. De Kluijver, M.J., Ingalsuo, S.S. & de Bruyne, R.H., 2021. Mollusca of the North Sea. Marine Species Information Portal. Leiden, The Netherlands: ETI Bioinformatics.  Available from:

  2. Giribet, G. & Peñas, A., 1999. Revision of the genus Goodallia (Bivalvia: Astartidae) with the description of two new species. Journal of Molluscan Studies, 65 (2), 251-265. DOI

  3. Hayward, P.J. & Ryland, J.S. (ed.) 1995b. Handbook of the marine fauna of North-West Europe. Oxford: Oxford University Press.

  4. Hayward, P.J. & Ryland, J.S. (ed.) 2017. Handbook of the marine fauna of North-West Europe. Oxford: Oxford University Press.

  5. Oliver, P.G., Holmes, A.M., Killeen, I.J. & Turner, J.A., 2016. Marine Bivalve Shells of the British Isles. Amgueddfa Cymru - National Museum Wales. Available from: [Cited:  3 July 2018].

  6. Tebble, N., 1976. British Bivalve Seashells. A Handbook for Identification, 2nd ed. Edinburgh: British Museum (Natural History), Her Majesty's Stationary Office.


  1. NBN (National Biodiversity Network) Atlas. Available from:

  2. OBIS (Ocean Biodiversity Information System),  2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. Accessed: 2024-05-18


This review can be cited as:

Lloyd, K.A., 2021. Goodallia triangularis Triangular astarte. In Tyler-Walters H. and Hiscock K. Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 18-05-2024]. Available from:

Last Updated: 21/09/2021

  1. Bivalve
  2. Mollusc