Critter of the week: Falsimargarita gemma - the iridescent Antarctic snail

This iridescent snail from the freezing cold, deep waters of Antarctica is Falsimargarita gemma (E. A. Smith, 1915). We found this specimen in the Ross Sea at 283 m, however there are also records of it from Scott Island seamount north of the Ross Sea, the Antarctic Peninsula and South Shetland Islands (128–2525 m).

Edgar Albert Smith, the taxonomist who originally described this beauty as Margarites gemma was a Zoologist and Malacologist (somebody who studies molluscs) at the British Museum (now the British Natural History Museum). This species and many others were identified and described by Edgar from the 1910 British Antarctic Expedition on the polar expedition ship Terra Nova.

Read more on Edgar Albert Smith.

Falsimargarita gemma (E. A. Smith, 1915) from the eastern Ross Sea shelf, Antarctica at 321 m. [Stefano Schiaparelli, MNA, Università di Genova, IPY-CAML 2008 Ross Sea voyage. Copyright LINZ]

Falsimargarita gemma is from the family Calliostomatidae, although it has also previously been placed in the family Margaritidae and Trochidae, which contains other shells with a beautiful iridescent lustre. We have introduced this group in the following blog post:

Critter of the week: a beautiful group of marine snails - the calliostomatidae

In this image of Falsimargarita gemma we can see those characters along with the horny operculum, which the snail can pull up to protect its soft body from predation.

The underside of Falsimargarita gemma (E. A. Smith, 1915). The horny operculum and the open umbilicus in the centre of the shell is visible. [Stefano Schiaparelli, MNA, Università di Genova, IPY-CAML 2008 Ross Sea voyage. Copyright LINZ]