A microscopic image of beer worms or bookworms. Photo: Stug Stug
An endangered beer worm that spent its life in ‘damp beer mats in Silesia’ is now turning up all over the world as a free-living microworm.
As a specialist journal, Bionieuws follows the rule of never writing in the first person: the editor is an observer, not a participant. As my career draws to a close, I am happy to break this rule for my story about the beer worm that was once called Turbatrix silusiae and with which I formed a special bond as a budding biologist. The species is listed in the two-volume Sesam-Atlas bij biologie (1970), compulsory textbooks that contained virtually everything a biologist needed to know. Under ‘Systematics’ on page 249, in the section on roundworms (nematodes), it states: ‘Tubatrix silusiae lives exclusively in damp beer mats in Silesia.’ The evolutionary biologist Richard Dawkins also mentions this species in The Selfish Gene as a species that bravely maintains its genes in the rather modest and vulnerable habitat beneath damp beer glasses. That is why, forty years ago, I wrote a piece in the Groningen biology journal calling on readers to keep their beer mats damp in order to prevent the beer worm from going extinct (Rauwkost, 1985). Now that the end of my career is in sight, I am glad to share how this species has fared.
Drawing from the article about the beer worm in the Groningen biology journal Rauwkost in 1985. Illustration: © Monique Mulder.
The species is now called Panagrellus redivivus – loosely translated: ‘brought back to life’ (redivivus), ‘commonly occurring’ (pan) ‘nematode’ (grellus). It is the same nematode that the founding taxonomist Linnaeus found in vinegar and bookbinding paste, named Chaos redivivum in 1767, and which has since endured at least thirteen name changes or reclassifications (Journal of Nematode Morphology and Systematics, 2009). Usually because the species turned up or was found in other obscure materials such as wallpaper paste, wheat porridge and rice gruel.
Genomic analyses of P. redivivus indicate that this species has succeeded in establishing a free-living existence across multiple niches (Genetics, 2013). Worldwide, these beer worms, bookworms or microworms are now reared in large numbers on oatmeal as live food for aquarium fish or as model organisms. Keeping beer mats damp is therefore no longer necessary for their survival – but it can hardly do any harm.