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Image of the Week: Periwinkle

28 Feb, 2014

B0004432 Radula ("tongue") of periwinkle. LM Nomarski image

Like the Brazilian, Gabonese and Rwandan flags – or a garish 1980s shell suit – this Image of the Week is blue yellow and green all over.

Unlike the flags and questionable attire, however, this collection of colours is a microscopic image of a living creature – part of a periwinkle. Periwinkles are small, edible sea snails, usually about one inch or less in size. The little molluscs live in the intertidal zone – which is the area above water at low tide and below it at high tide.

The colourful tints of the image are derived from Nomarksi optics. Named after the Polish physicist who created the technique, the process highlights colour contrasts – and is frequently used to study live specimens.

Whilst the above looks a bit like a rib cage, the pointy parts of the image are actually a periwinkle’s tiny teeth, which are in rows on a structure called a radula – which acts a bit like a tongue. The little sea creatures use the radula to scrape algae off of rocks. They break down the food by mixing it with mucous on the radula before bringing the food into their mouth – perhaps not the nicest sounding condiment or seasoning!

Image credit: Spike Walker, Wellcome Images

Wellcome Images is one of the world’s richest and most unusual collections, with themes ranging from medical and social history to contemporary healthcare and biomedical science. Over 100,000 high resolution images from our historical collections are now free to use under the Creative Commons-Attribution only (CC-BY) licence.

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