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Animals of the Great War, Part 8: The Slimiest Heroes


2014 marks the hundredth anniversary of the beginning of World War I. In addition to humans, the war involved millions of animals - from horses to pigeons to slugs! In this special year, Barnfield House Veterinary Centre is sponsoring a series of articles remembering animal helpers, heroes and victims of the war written by Laura Brown now working for the Bat Conservation Trust.


World War I signalled the dawn of widespread chemical warfare. Mustard gas sickened countless soldiers. Although troops were issued with gas masks, by the time they smelled gas it was generally too late. The chemical had begun its work, burning their skin and the lining of their lungs. Many weeks of pain and disability followed, and sometimes victims died of their injuries.

The search was on to find a way to detect gas before it caused harm. A few dogs, like Sergeant Stubby (discussed in previous article), were able to warn their human colleagues of gas attacks, but in general using dogs did not prove successful. Neither did attempts to use cats, rodents or insects. Either these animals were not able to detect gas before humans, or they developed pneumonia within a short period of time -- which was not only cruel, but meant that the animals would constantly need to be replaced.

But there was one creature that could detect gas early without getting ill, and it would slither out from an unexpected part of the animal kingdom.

After their own trials failed, the U.S. Army asked scientists at the Smithsonian Institute for help. One of the Smithsonian’s star scientists was Paul Bartsch, a curator in the Division of Molluscs. Bartsch had published papers on the snails of South Africa and the Philippines, but his work for the Army drew on an experience closer to home.

A few years before, Bartsch had been keeping some great grey slugs in his house when they escaped and began roaming slimily around the building. Bartsch noticed that when they reached the furnace room, they appeared distressed. He conducted some experiments and found that the slugs would react even to very low levels of furnace fumes. Although they would become visibly agitated, the fumes would not do them any lasting harm, because they were able to close their breathing apparatus until the danger had passed.

Bartsch wondered if slugs could detect mustard gas as well as furnace fumes. He found that they could, and that they were three times as sensitive to the gas as human beings. This meant that if slugs were kept in the trenches, their distress signals could warn humans of a gas attack, giving soldiers a chance to put on their masks before the gas reached levels that could hurt them. The slugs were also convenient to use, because they required very little care.

During the last five months of the war, slugs were placed in the trenches with American soldiers, and were credited with saving many people from death or injury.

After the war, the slugs presumably slid away into the soil of Europe (they would have been at home there, since they are a native European species and were only introduced to North America by accident). Unlike the mammals and birds that helped humans with the war, they have not been honoured with medals or memorials. And while the type of animal research the Army conducted is now tightly controlled when performed on vertebrates, the welfare of invertebrates has very little protection under the law.

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