Critter of the Week – The fig shell, Thalassocyon tui

This week we introduce a beautiful treasure of the deep, Thalassocyon tui a sea snail generally found in northern New Zealand waters, with records from the Chatham Rise, Challenger Plateau and north to the Colville and Kermadec Ridges, and down to abyssal depths 750-3034 m.

It belongs to the fig shell family, the Ficidae, named for the shape of their thin shells that apparently resemble a fig or pear. When comparing our New Zealand species with other members of the family (e.g. 1) it becomes apparent that T. tui, a rather spiky member of the family, doesn’t really look the part.

This species was described by Richard Dell in 1967. Richard was an eminent New Zealand malacologist (scientists specialised in molluscs) with many publications on New Zealand and Antarctic species. The original specimens of Thalassocyon tui were collected on the “Tui” cruise to waters immediately north of New Zealand in 1962, which Richard Dell participated in, hence the choice of species name to honour the New Zealand Royal Navy vessel HMNZS Tui (2) . The HMNZS Tui was a wartime minesweeper but was converted for oceanographic research in 1955 and you can see a picture of her here (3).

The holotype of Thalassocyon tui is kept at the Te Papa, Museum of New Zealand collections in Wellington:

Thalassocyon tui at Te Papa





This beautiful specimen of Thalassocyon tui was collected at 1379 m deep on Rumble II Seamount in the Kermadec Ridge Seamount Chain and is about 5 cm high. [Rob Stewart]