Many people assume spiders dislike water, observing them avoid wet areas. While spiders don’t experience emotions like “hate,” their interactions with water are governed by their biology and survival instincts.
Why Spiders Appear to Avoid Water
Spiders do not possess lungs like mammals but instead breathe through specialized respiratory organs called book lungs. These structures contain numerous thin, leaf-like plates arranged like pages in a book, providing a large surface area for gas exchange. When a spider is submerged in water, its book lungs can fill, preventing oxygen absorption and leading to suffocation.
The unique properties of water, particularly its surface tension, also play a significant role in how spiders interact with it. For smaller spiders, water droplets can act as a trap; if they break through the surface film, they can become ensnared and unable to escape. Even if not fully submerged, water clinging to their bodies can impede their movement, making it difficult to walk or climb effectively.
A spider’s body is covered in fine hairs, or setae, important for sensory perception and locomotion. Water can mat these hairs, disrupting their ability to sense vibrations, air currents, or chemical cues in their environment. This interference can hinder their hunting capabilities and their ability to detect and escape from predators.
Spiders’ Relationship with Water in Nature
Despite the challenges water presents, spiders in their natural habitats frequently interact with it for survival. Many species obtain necessary hydration by drinking dew droplets that accumulate on webs or vegetation, or by sipping from small puddles of standing water. This consumption is fundamental for their physiological needs, especially in dry environments.
Some spiders have remarkable adaptations to utilize water surfaces. Species like the raft spider (Dolomedes fimbriatus) can walk or even run across the surface of water, using the principles of surface tension and specialized hydrophobic hairs on their legs to distribute their weight. These adaptations enable them to hunt aquatic insects or small fish near the water’s edge. The diving bell spider (Argyroneta aquatica) constructs an underwater silk web, filling it with air to create a submerged “diving bell” for living, eating, and reproducing.
Spiders cope with rain in various ways. While heavy rainfall might encourage some to seek immediate shelter, many common garden spiders simply remain on their webs. Their silk can be remarkably water-resistant, allowing them to withstand moderate precipitation without damaging their web or hindering movement.
Water as a Spider Deterrent
Using water as a deterrent for spiders is often considered by homeowners. Spraying a spider with water will cause it to move away, as it seeks to avoid becoming wet and the discomfort or danger. However, this is a temporary solution, as the spider will simply relocate to a drier spot nearby rather than being permanently removed.
Water is not a sustainable or effective long-term method for spider management. While a direct spray might dislodge a spider, it does not address the underlying reasons for its presence, such as available food sources or shelter. Relying solely on water for pest control can even be counterproductive in some cases.
Excessive moisture indoors can attract other insects like silverfish or moisture-loving beetles, which become a food source for spiders. This can inadvertently create a more appealing environment for spiders. Effective spider management involves reducing clutter, sealing cracks, and controlling other insect populations, rather than direct water application.