Slugs are soft-bodied mollusks that lack an external shell, making them highly susceptible to drying out. Their slow movements and tendency to remain hidden often lead to confusion when they are encountered motionless. Determining if one is resting, dormant, or deceased is difficult. Assessing a slug’s behavior and physical needs is the most reliable way to determine its status.
Immediate Signs of Activity
A slug that is alive and actively moving leaves behind a clear, wet trail of mucus produced by the pedal gland. Observing a fresh slime trail nearby is a definitive sign of recent movement, even if the slug is currently stationary. Slugs use this mucus for locomotion, creating a slippery surface that allows them to glide forward using rhythmic muscular contractions.
Movement is purposeful and involves subtle shifting of the body or independent movement of its tentacles. The larger upper pair of tentacles hold the light-sensitive eyespots and can be extended, retracted, and moved independently for sensing the environment. A gentle touch or soft puff of air may prompt a response, such as a localized muscular contraction or the retraction of the tentacles. A moist, plump body texture is also a good indicator of life, as slugs must retain moisture to survive.
Recognizing Dormancy vs. Death
Slugs enter dormancy, known as aestivation, as a survival mechanism against extreme environmental stress like dryness and high temperatures. During this period, the slug significantly slows its metabolism and remains motionless in a sheltered, cool, and damp location. This state causes the slug to appear rigid and lifeless, making it easily mistaken for a dead specimen.
To distinguish dormancy from death, a practical test involves creating a favorable environment. Gently move the slug to a container with a cool, moist surface, such as a damp paper towel or wet soil, to provide conditions for revival. A slug in aestivation will begin rehydration and return to activity within 30 minutes to an hour if it is alive. If the body remains rigid and unresponsive after this period, it is likely deceased.
Irreversible Indicators of Death
A truly dead slug exhibits physical signs of irreversible tissue breakdown and desiccation. The most obvious indicator is severe desiccation, where the body is completely dried out, shriveled, and brittle to the touch. This shriveled appearance results from the loss of body moisture that their shell-less anatomy cannot protect against once life ceases.
Another sign is the presence of a strong, foul odor resulting from decomposition. Unlike a live or dormant slug, a dead one rapidly begins to decay, emitting a distinct, unpleasant smell. Furthermore, any slug displaying visible physical damage, such as a severed body or the growth of mold or fungus on its tissues, is definitively deceased. If the slug remains entirely unresponsive and physically shriveled after the dormancy test, it is safe to conclude that it is no longer alive.