Can Spiders Breathe Underwater & How Long Can They Survive?

Spiders are air breathers, and no spider species has gills or any organ that extracts dissolved oxygen directly from water the way a fish does. Yet a surprising number of spiders survive underwater for hours, days, or even weeks by carrying their own air supply, building submerged breathing chambers, or slowing their metabolism to a near-standstill. One species, the diving bell spider, spends virtually its entire life submerged. The strategies spiders use to pull this off are more varied and more effective than most people expect.

How Spiders Breathe on Land

Understanding what happens underwater starts with what happens on dry ground. Most spiders have two breathing systems working in tandem. Book lungs are layered structures in the abdomen that function somewhat like pages of a book, with hemolymph (the spider equivalent of blood) flowing through thin plates exposed to air. Tracheae are tiny tubes that carry oxygen directly to tissues, bypassing the circulatory system entirely. These two systems are complementary: species with more developed tracheae tend to have smaller, less developed book lungs, and the balance shifts depending on how active and oxygen-hungry the spider is.¹

Both systems require air. Book lungs need air flowing over those thin plates, and tracheae need open spiracles (small openings on the abdomen) to let air in. Submerge an ordinary garden spider in water with no air access, and it will suffocate. The question is how so many species have found workarounds.

The Diving Bell Spider, the Only Truly Aquatic Species

Argyroneta aquatica is the standout. Found in freshwater ponds, lakes, and slow-moving streams across Europe and parts of Asia, it is the only spider that lives almost exclusively underwater. It hunts, mates, and raises young while submerged, surfacing mainly to replenish air.

The spider constructs an underwater dome of silk anchored to aquatic vegetation. This silk is not ordinary webbing. Research has shown the bell wall is a composite structure of stiff anchor threads, bundles of crossing fine threads, and a proteinaceous hydrogel that fills in the gaps, making the wall airtight. Small air bubbles pressed against this composite cannot pass through and remain perfectly spherical at the contact point, confirming there are no mesh openings.² The spider fills this dome by making repeated trips to the surface, trapping air bubbles on its abdomen, and ferrying them down.

The bell does more than just store air. It functions as a physical gill: oxygen from the surrounding water diffuses into the bubble while carbon dioxide diffuses out, partly replenishing the air supply without the spider needing to surface. Analysis of the bubble’s gas exchange suggests the maximum “gill factor” for an average spider in an average-sized bell is roughly eight, meaning the spider can extract about eight times more oxygen than was originally in the bubble before it must surface again.³ In practice, this allows the spider to stay submerged for extended periods, surfacing perhaps once a day or less under favorable conditions.

Even outside the bell, the spider carries a thin film of air on its abdomen, held in place by a layer of superhydrophobic hairs. This trapped air layer is remarkably stable and does not simply float away, because the geometry of the hairs creates surface-tension forces that keep the bubble intact.⁴ The spider even spins silk thread anchors while surrounded by this air envelope, with symmetric movements of its spinnerets ensuring the air stays in contact with its body during the process.⁵

Intertidal Spiders and Weeks of Submergence

The diving bell spider gets most of the attention, but the intertidal spider Desis marina, found on rocky shores in New Zealand, may be the more impressive survivor when it comes to sheer duration. These spiders live in the holdfasts of bull kelp, which are submerged by the tides twice a day. Individuals living low on the shore, down to 77 centimeters below mean sea level, face up to 19 consecutive days of submergence as tides shift over the lunar cycle.⁶

Desis marina survives this through a combination of adaptations. It seals itself inside a silk-lined air pocket within the kelp holdfast, trapping enough air to breathe during submergence. Its metabolic rate is remarkably low, less than half that of comparable terrestrial spiders at the same temperature. It can also tolerate extreme oxygen depletion, functioning until oxygen partial pressure drops to just 12% of normal atmospheric levels. Together, these traits led researchers to calculate that the “physical gill effect” of the trapped air, with dissolved oxygen diffusing in from the surrounding seawater, could theoretically sustain even the largest individuals for more than 100 days underwater.⁷ That figure is a theoretical maximum under ideal conditions, not something regularly tested in the wild, but it illustrates how effective the combination of low metabolism, hypoxia tolerance, and physical gill breathing can be.

Hypoxic Coma as a Survival Strategy

Some salt-marsh spiders take a different approach entirely. Rather than maintaining an air supply and staying active, they essentially shut down. The salt-marsh spider Arctosa fulvolineata, which lives in coastal habitats that flood regularly, enters a hypoxic coma when submerged. This is not simply drowning in slow motion; it appears to be a controlled physiological response. Oxygen deprivation triggers a coma-like state that dramatically reduces the spider’s metabolic demands. When the tide recedes and air becomes available again, the spider revives.⁸

This strategy is more pronounced in Arctosa fulvolineata than in related species from drier habitats, suggesting it is genuinely an adaptation to regular tidal flooding rather than a generic stress response. It represents an entirely different survival philosophy compared to the diving bell or the sealed air-pocket approach: instead of breathing underwater, the spider stops needing to breathe much at all.

Running, Swimming, and Riding It Out

Not every spider that encounters water has a specialized underwater survival kit. Many species that live near water deal with flooding the simplest way possible: they flee. Marine-associated spiders employ a range of inundation strategies including air bubble respiration, airtight nests, hypoxic comas, and simply running from incoming tides.⁹

For species that cannot escape rising water, swimming and floating are genuine options. Studies of two South American burrowing wolf spiders in the genus Allocosa, which inhabit flood-prone sand dunes along a river, found that all individuals survived experimental flooding with no deaths. The spiders used a mix of diving, floating on the surface, and active swimming to cope. There were clear differences in behavior between the species: Allocosa senex performed more dives and floated more often and swam for longer than Allocosa marindia. Females of both species swam more frequently than males.¹⁰ The behavioral differences tracked with each species’ ecology and life history, reinforcing the idea that flood responses are shaped by how frequently a population actually encounters water.

Many spiders that end up on water can walk or skate across the surface film thanks to their hydrophobic leg hairs, which is a different trick from underwater survival but often the first line of defense when conditions get wet.

What Determines How Long a Spider Can Last

There is no single answer to “how long can a spider survive underwater” because the timeline depends enormously on the species and the mechanism it uses. A common house spider that falls into a bathtub with no air bubble might drown within an hour or two. A diving bell spider in a well-oxygenated pond can remain submerged indefinitely, surfacing only briefly. Desis marina in a kelp holdfast can survive nearly three weeks of continuous submergence in the field and, by one estimate, could theoretically last over 100 days. A salt-marsh spider in a hypoxic coma may tolerate several hours without oxygen before needing air.

The key variables are whether the spider has access to trapped air, whether the surrounding water is oxygenated enough for a physical gill effect to work, how low the spider can drop its metabolic rate, and how well it tolerates low oxygen. Temperature matters too. Cold water holds more dissolved oxygen, and cold-blooded animals burn less energy in colder conditions, so a spider in cool water generally lasts longer than one in warm water. The Desis marina respiration studies were conducted at 17.5°C, a moderate temperature for a New Zealand shore; warmer conditions would shorten survival times.

Water Quality Can Make or Break the Strategy

The physical gill mechanism that keeps many spiders alive underwater is sensitive to environmental conditions in ways that are easy to overlook. Because the gill depends on dissolved oxygen diffusing from the water into the air film, it only works when the surrounding water is reasonably well oxygenated, close to atmospheric equilibrium. Water polluted with decomposing organic matter often has severely depleted oxygen, which would choke the gill effect and leave the spider with only the oxygen originally trapped in its bubble.¹¹

Oil spills and detergent pollution pose a different threat. The entire system depends on superhydrophobic surfaces, those water-repellent hairs that keep the air film stable against the spider’s body. Surfactants in detergents and the chemical properties of oil can destroy this hydrophobicity, collapsing the air film and leaving the spider unable to carry or maintain its air supply. In practical terms, a population of diving bell spiders or intertidal spiders could be wiped out not by water itself but by a change in water chemistry that disables their breathing apparatus. Researchers have noted that the sensitivity of physical-gill organisms to water quality may make them useful bioindicators of aquatic ecosystem health.¹¹

Where These Spiders Choose to Live

The diving bell spider does not set up shop randomly. Studies of Argyroneta aquatica populations in Italian freshwater springs found that the spiders were significantly associated with areas that had both high prey availability and low predator density.¹² Living underwater is energetically expensive and makes the spider vulnerable during surface trips, so habitat selection appears to reflect a trade-off between food access and predation risk. A site with plenty of aquatic invertebrates to eat but few fish or other predators lurking nearby is ideal.

For intertidal Desis species, the constraint is different. They are distributed across the tidal zone, but those living lower on the shore face longer submergence and need larger or more reliable air pockets. The kelp holdfast itself is the limiting resource: it must be structurally sound enough to retain trapped air and large enough to hold a sufficient volume for the spider’s size.⁶ A spider in a tiny, leaky holdfast far below the tideline is in real trouble.

Independent Evolutionary Origins

One of the more interesting findings from recent genomic work is that aquatic and semi-aquatic lifestyles have evolved independently multiple times in spiders. The diving bell spider Argyroneta aquatica and the intertidal Desis spiders are not closely related and did not inherit their water-associated habits from a shared ancestor. Molecular dating estimates that the lineage leading to Argyroneta diverged from its closest terrestrial relatives around 44 million years ago, while the Desis lineage belongs to a separate family that diverged roughly 56 million years ago. Both groups arose independently from fully terrestrial ancestors.¹³

Broader phylogenetic studies of the dictynid spider family, which includes Argyroneta, have confirmed that an aquatic habitat association has arisen multiple times even within that single family.¹⁴ This suggests that the raw materials for aquatic adaptation, hydrophobic body hairs, silk production, low metabolic flexibility, are widespread enough among spiders that water-associated lifestyles keep re-evolving whenever ecological opportunity arises. The fact that the specific strategies differ so much across lineages (diving bells versus sealed nests versus metabolic shutdown) only underscores that there is no single “aquatic spider blueprint.” Each lineage has independently assembled its own toolkit from available parts.

What Happens if You Find a Spider in Water

If you spot a spider floating in a pool, bathtub, or bucket, it is almost certainly not one of these specialized aquatic species. Ordinary house spiders and garden spiders that fall into water are in genuine danger. Their hydrophobic leg hairs will keep them on the surface for a while, but if they get pulled under or become waterlogged, they can drown. Lifting them out with a piece of paper or a cup is a reasonable thing to do if you are so inclined. The spider is not holding its breath in any sophisticated way; it is simply trapped.

Semi-aquatic spiders like fishing spiders (Dolomedes species), which you might encounter near lakes or streams, are a different story. They regularly walk on water, dive below the surface to catch prey, and carry air films on their bodies during short dives. They are not as committed to underwater life as Argyroneta, but they handle submersion with ease for minutes at a time. If you see a large spider sitting on the surface of a pond, it is not stuck. It is hunting.

The broader lesson from spider underwater survival is that “breathing underwater” does not require gills or any aquatic breathing organ. It requires managing air supply cleverly enough that the spider never actually switches to breathing water. Whether that means building a silk dome, sealing a kelp holdfast, coating the abdomen in a thin film of trapped air, or shutting down metabolism until the flood passes, every spider strategy is fundamentally about keeping air in contact with its respiratory organs while surrounded by water. The ceiling on survival time is set by how efficiently the spider can stretch that air supply and how well the surrounding water cooperates in replenishing it.