This article discusses about the swimming capabilities of spiders. By the end of this article, the reader will be able to know the species of spiders that have been observed to swim and those that have not been observed to do so.
The reader will also see some of the most prominent adaptations that have made swimming in spiders possible.
Can spiders swim?
Yes, some species of spiders can swim while others cannot. Those that swim or like to explore water are known as semiaquatic and aquatic spiders, and they mostly inhabit fresh water habitats like ponds and lakes.
What type of spiders swim?
Semiaquatic and aquatic spiders swim. The regular spiders you find within and around the basement, attic, or general living spaces at home will not be able to swim. They’ll only end up drowning after several hours of struggle when tossed into water.
Semiaquatic spiders are built for the waters, and they are mostly found around ponds, lakes, rivers, canals, marshes, slow-moving streams and other freshwater habitats.
They have some highly impressive adaptations that enable them to walk on water, move through water and even dive underwater and stay there for as many hours as they like or even as long as a lifetime depending on species.
Often, semiaquatic spider explore fresh water habitats in order to pounce on aquatic animals like fishes or crabs or hide from persistent predators like the parasitoid wasps.
Semiaquatic spiders include species of the Ancylometes, Dolomedes, Megadolomedes, Pardosa, Pirata, Thalassius and Desis group. Bear in mind that not all spiders found within these groups are semiaquatic, some like the tree-dwelling D.albineus of the Dolomedes group are known to be strictly terrestrial and prefer to live most of their lives within the safety of the trees.
While the groups mentioned above consist of spiders that are half aquatic and half land dwelling, one distinct group not mentioned above is known to live it’s life almost entirely underwater.
The group is known as the Diving bell spiders and belongs to the genus of spiders called Argyroneta. The members have been observed to do most of their resting, hunting, feeding and reproduction underwater.
Diving bell spiders, just like their semiaquatic brothers are found commonly within or around freshwater habitats with aquatic vegetation, such as lakes, ponds, canals, marshes and slow-moving streams.
Why are some spiders aquatic and others not
Evolution is the reason why the entire population of spiders is dispersed across every corners of the globe: both on land and in the waters, with the exception of Antarctica.
It’s old and uncommon history that the archaic of spiders first appeared about 400 million years ago and over time, evolved and gave rise to thousands of modern species that walk the surface of earth today.
During the course of the complex evolution, the resulting offsprings from these ancestors took to different paths, colonizing different areas around the world and settling in different habitats within these areas.
In light of this, some modern ancestors of spiders chose to live near regions that were close to water bodies and overtime, they began moving closer and closer to aquatic habitat, inhabiting pond areas, swampy areas and intertidal zones where land areas were constantly above water level during low tides and underwater at high tides.
Soon, these ancestors became even more used to living near water bodies that they began developing adaptations and bodily features to facilitate hunting and survival around this newly found home.
Eventually, some of them (very few species) migrated partially and some full time into aquatic habitation and are now the aquatic and semiaquatic spiders that we know of today.
Most semiaquatic spiders feed on small underwater creatures like fishes and tadpoles in addition to their terrestrial diets of insects and other small animals.
Aquatic adaptations of spiders
There are few characteristics that semiaquatic and aquatic spiders have that distinguish them from terrestrial ones and also enables them to jump into the waters without the risks of drowning. These characteristics include.
1) Hydrophobic hairs for floating and swimming
Semiaquatic spiders have the ability to float and walk on water all thanks to their lightweight and special legs which are hydrophobic (or water resisting) in nature; creating so much surface tension that they barely touch water, creating dimples around contact points, and as a result keeping the animals afloat.
To move, the spiders then exert force on the dimples of water created around their legs while simultaneously lifting their legs in the forward stroke. This enables them to walk on water.
Another way that spiders move around on water is by galloping; that is, slapping the surface of water to move quickly in response to threats or feeding opportunities, similar to what is observed in certain lizards.
On lazy days, spiders simply use the wind to their advantage to move around on water. They may stand tiptoes or prostrate themselves on water and stick two legs in the air and allow the breeze sail them to their destinations.
Surface tension is a phenomenon that affects the top layer of water, causing it to behave like a stretched elastic sheet.
This stretched membrane allows insects, and other creatures that are lightweight and having hydrophobic features on their bodies or something of sort, to be able to float on it.
If you’ve ever floated an office pin or witnessed someone doing so, that simple surface tension on display. Thats what some species of spiders like the tarantulas use to float and walk on water like magicians.
2) Breathing under water
Semiaquatic spiders use air bubbles trapped on their bodies and legs to breath underwater. When they swim underwater, air bubbles collect around their bodies which forms a super thin blanket of air and gives them the appearance of a fine polished silver.
The air layer around the abdomen supplies their book-like lungs with the necessary oxygen required for proper respiration underwater. Spiders don’t require high levels of oxygen, as a matter of fact, they only require a very little amount to keep their cells and this body conditions at optimal. So air bubbles as little as that can go a long way in sustaining them for extended periods.
Most semi-aquatic spiders can survive several minutes underwater and some can last an outstanding hours on end without rising to catch a breath.
3) Breathing underwater (diving bell or fully-aquatic spiders):
Just like semiaquatic spiders, diving bell spiders also breath using the same air bubble principle, but in order to fully submerge underwater for prolonged periods, they must construct an underwater oxygen tank with their fibrous silk.
The tank, similar to how a diving bell functions, hence the name of the spider, is made from irregularly constructed sheets of silk and an unknown protein-based hydrogel.
The structures is spun between the stems of submerged water plants and then inflated with air bubbles brought down from the water surface by the spider.
When the air begins to run out, the spiders makes a journey to the surface, collects air bubble around its abdomen, transverse back to the tank and re-inflates it again. This might take several trips to complete.
To use the oxygen tank, spiders simply insert their abdomen into the tank to collect air bubble which will then be used in the way we explained in the second point above.
Diving bell spiders often feed and reproduce exclusively within their oxygen tank.
The semiaquatic species of spiders
1) Fishing spiders
Fishing spiders are members of the Dolomedes group of spiders where almost all species are semiaquatic. They use water medium mostly to prey on aquatic organisms and hide from predators.
They reside on water surface and locate preys using tiny hair spikes on their legs that detect (even the most little) vibrations from aquatic animals (i.e fishes and tadpoles).
To catch their preys, they anchor their back legs onshore, on fallen twigs or leaves and float silently on water surface while waiting for curious and investigative victims to come within reach, then they quickly wrap their front legs around the prey and inject toxic venoms quickly to paralyze them.
Fishing spiders have been observed to hunt down fishes about 2.2 times their total body size.
Fishing spiders can dive underwater to avoid wasps, but at times this method can be highly ineffective since wasps are also able to tolerate water (not for that long though) and can quickly counter this move by following the spider underwater, injecting them with highly potent venom and dragging their dead bodies out of the water for devouring.
2) Diving bell spiders
Diving bell spiders are the only members of the genus Argyroneta and they are known to spend most part of their lives underwater, supplying themselves with oxygen using an underwater bubble system.
Diving bell spiders reproduce inside their oxygen tanks, and usually in the females’s tank because it’s often the much larger and bigger in construction size compare to those of the males.
3) The giant water spider of Australia
The giant water spider belongs to the genus Megadolomedes and also happens to be another species that is semiaquatic.
The spider, as the name suggests is a giant creature of its modal habitat having leg span of upto 28 cm at full stretch.
Water spiders are able to walk on water using hydrophobic hairs that take advantage of the surface tension of water, and are also able to survive underwater for several hours while looking for preys to catch.
These spiders although, aquatic, also spend a heavy chunk of their time on land too performing many activities like feeding and reproduction.
Giant water spiders often go into the waters mainly to catch their preys of tadpoles, small fishes and aquatic insects. Their habits is often around lakes and ponds.
Can spiders survive flood?
According to a research published in 2009, most spider species that inhabit marshy areas or territories that periodically get flooded are capable of entering into a coma-like state as a physiological adaptation to survive flood.
So they greatly reduce their oxygen consumption to be able to survive the several hours that tropical floods may persist above ground levels.
More interesting articles
- How long can spiders live without food and water?
- Spider Hearing: Can spiders hear?
- Can spiders drown?
Cite this Article ” (APA Format)
Bunu. M. (2020, May 15). Can spiders swim. Retrieved from http://emborawild.com/can-spiders-swim/