Peter Williams is a naturalist with a lifelong interest in molluscs. A retired medical doctor, he is the author of several books, including on snails and jellyfish. He even has a subspecies of snail named after him.
Ahead of the publication of Slugs: A Natural and Cultural History, we had the pleasure of talking to Peter about the book and his case for a more balanced appreciation of the frequently slandered animal.

Often misunderstood and famously maligned, terrestrial slugs seemingly haven’t quite managed to capture our hearts. What inspired you to build a case for their appreciation?
I have always been attracted to maligned animals, particularly invertebrates. Slugs are arguably the most maligned. Regarded as pests and provoking disgust in humans, they don’t even have an attractive shell which can be appreciated. Instead, they have a soft, extensible body and produce a sticky, adherent slime. However, we should not be in a hurry to judge slugs since they are important composters and without them, we would see an increase in rotting vegetation in our gardens. They also should be appreciated for the role they play in the food web. Of interest too is their resilience to predators, man included. I felt the time had come for a reappraisal.

Less despised and less frequently encountered are the charismatic cousins of the terrestrial slug: sea slugs. They feature prominently in the book. How did you approach introducing the complex realm of nudibranchs and pteropods?
Sea slugs, while not producing the same antipathy as their land relatives, are certainly less often encountered by the public, except amongst scuba divers or those that swim amongst coral reefs. Though they tend to be small, they are usually very colourful. The sight of them will usually arouse the interest of underwater photographers. Researching them worldwide, I was amazed at their diversity and their flamboyant colours and bizarre shapes. Knowing the contribution made by one in particular, Aplysia, to our understanding of nerve conduction and memory, increased my interest in these animals. As for Pteropods, the sea butterflies and sea angels, these free-swimming creatures are an important part of the plankton, a source of food for fish and seabirds, but they are also indicators of acidification of the oceans and so important in monitoring climate change. I felt these were aspects that needed to be explored further in the book.

Slugs covers an expensive array of species but for the eager slug enthusiast there is much more to discover. How did you decide which species, behaviours and stories to include?
My intention was to introduce slugs to as wide an audience as possible, not just gardeners who regard them as pests, but those with a keen interest in natural history. Their internal anatomy, their mating habits, and recent research into their behaviour, not to mention their ability to withstand predation, seemed to me potentially interesting features and ones not widely appreciated. The choice as to which species to include wasn’t always an easy one, but any unusual features, be they in appearance, habits or distribution, helped in the selection of species. For example, some are selective feeders, particularly sea slugs, while others are wider in their eating habits, a feature reflected in their teeth, which are renewable.
Your book convincingly conveys many examples of their fascinating biology, behaviours and variation. Did you make any particularly exciting personal discoveries while writing Slugs?
Having written a book on jellyfish, I was intrigued to know what animals withstood their stings. What I hadn’t realised was that the Blue Sea Dragon, a pelagic sea slug which eats Physalia, the Portuguese Man o’ War, actually extracts its stinging cells to use in its own defence. Amongst terrestrial slugs, the ones living in Australia proved to be particularly exotic. One with a fluorescent pink colour is only found on Mount Kaputar, confined to the summit of that one mountain in New South Wales. Another, the Red Triangle Slug, produces mucus that is so sticky it can trap predators as sizeable as tree frogs. While I have encountered many slugs, I have made no unique discoveries, unlike their shelled relatives where I have a subspecies of snail named after me.

I was fascinated to learn of the potentially revolutionary role that research into both terrestrial and sea slugs could play in medical research. Could you tell our readers a bit about this?
The history of slugs providing cures for human ailments stretches back a long way, from treating stomach ulcers to tuberculosis. Sadly, most of the cures are not supported by evidence. It does appear however that slug mucus contains an ingredient that promotes healing of wounds and can also be used as glue in surgical procedures. The anti-inflammatory and antioxidant properties of slug mucus are currently being examined. Also, it is known their mucus can reduce the survival of melanoma cells, so may be a useful cytotoxic agent in the future. Medical research might benefit too from a better understanding of a sea slug’s ability to regenerate damaged body parts. It reaches its apogee in two species of Elysia which are able to detach their bodies and regenerate new ones from the remaining head remnant.
The book explores many depictions of slugs in folklore, mythology, art and culture. What have you noticed about human evocations of slugs, and do you think the way we see and represent them might change in the future?
Slugs, like snails, feature in pictures as symbolic creatures, as they have in some sculptures. In Chetwynd’s giant, glowing slugs which stood outside Tate Britain for a while, they embodied the idea of renewal during the darkness of winter. Mostly however, slugs are depicted as alien creatures, not integrated with other animals, remaining as ‘outsiders’ in nature. Talk is often of their elimination rather than their preservation, though controlling their numbers without harming other animals is a difficult task. My hope is that people will come to a more balanced view of slugs, regarding them as useful composters rather than pests, and realising their importance in the food chain. They also illustrate how a slower pace of life offers advantages to us. The ‘Slow Movement’ may have a snail as its emblem. It could just as easily be the terrestrial slug!



What do you consider the most important points for readers to take away from your book?




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