Spider survival in water is not a simple yes or no question. Their ability to endure aquatic environments varies significantly, depending on the spider’s species, its biological adaptations, and the specific circumstances of its encounter with water. Some spiders can only withstand brief submersions, while others have evolved strategies to live almost entirely underwater.
Terrestrial Spiders and Water
Most spiders are terrestrial. When these common spiders encounter water, their survival is limited. Their bodies possess a hydrophobic exoskeleton, covered in tiny hairs (setae) that prevent water from wetting their surface. This adaptation allows them to trap a thin film or bubble of air around their body when submerged, creating a temporary oxygen supply. While this air film helps them survive accidental plunges for short durations, prolonged submersion is fatal as the trapped oxygen eventually depletes.
Truly Aquatic Spiders
A few spider species are adapted to aquatic or semi-aquatic lifestyles. The diving bell spider, Argyroneta aquatica, is the only spider known to live almost entirely underwater in freshwater habitats across Europe and Asia. This spider constructs a dome-shaped web, known as a “diving bell,” between submerged aquatic plants. It repeatedly transports air bubbles from the water’s surface, using hairs on its abdomen, to inflate this silk structure. This ‘bell’ functions as an external gill, extracting oxygen from the surrounding water, allowing the spider to inhabit it for extended periods for resting, feeding, mating, and raising offspring.
Fishing spiders, belonging to the genus Dolomedes, are another group of semi-aquatic spiders. These spiders are often found near ponds, streams, and other bodies of water, exhibiting an ability to walk on the water’s surface due to surface tension and their water-repellent legs. They are skilled hunters, sensing vibrations on the water to locate prey like insects, tadpoles, or small fish. When threatened or pursuing prey, fishing spiders can dive underwater, carrying a temporary air bubble trapped by their bristly hairs, and can remain submerged for up to 30 to 90 minutes.
Spider Respiration Explained
Spiders do not possess lungs similar to mammals, nor do they ‘hold their breath’ in the conventional sense. Instead, they breathe through specialized respiratory organs: book lungs and/or tracheae. Book lungs are structures composed of stacked, plate-like tissues resembling the pages of a book, where gas exchange occurs passively as air circulates between these ‘pages.’ Many spiders also have tracheae, a system of small tubes that branch throughout the body, delivering oxygen directly to tissues.
Gas exchange in spiders primarily relies on passive diffusion rather than active pumping of air. Oxygen from the air moves into the spider’s hemolymph, a fluid similar to blood, and carbon dioxide moves out. When a spider is submerged, the trapped air bubble serves as a temporary reservoir for this gas exchange. Without access to fresh atmospheric air, the oxygen in the bubble will eventually be consumed, and carbon dioxide will accumulate, limiting the spider’s underwater survival time unless it can replenish its air supply or is adapted to extract oxygen from water like the diving bell spider.
What Affects Water Survival
The duration a spider can survive in water depends on several factors. The primary factor is the spider’s species, due to the specialized adaptations of aquatic spiders compared to terrestrial ones. Water temperature also plays a role; colder water can reduce a spider’s metabolic rate, potentially allowing it to survive longer by slowing its oxygen consumption. The quality of the water is another important consideration; the presence of detergents or soaps, for instance, can break the surface tension and compromise the hydrophobic properties of a spider’s exoskeleton, making it impossible for them to trap an air bubble and leading to rapid drowning. The duration of submersion also limits survival; even for adaptable spiders, there is a limit to how long they can remain underwater without fresh air.