Discreet spider, the Argyronetus lives, hunts, feeds, reproduces, under water. Often unknown inhabitant of our ponds, it leads an original life, totally adapted to the aquatic environment.
An aquatic spider
It lives underwater in the middle of fish, frogs and dragonfly larvae. The Argyronet, Argyroneta aquatica, is the only spider known to lead its complete life cycle in an underwater habitat. Without gills, with its aerial respiratory system, it has managed to invest the third dimension of the aquatic world. And among spiders, it reigns as the uncontested master. Of small size, 8 to 15 mm, it knew how to adapt with ingenuity to an environment full of resources. The only one of its kind, of the family Dictynidae, it can be found in the whole Palearctic area.
It lives underwater but breathes oxygen from the air
The Argyronete has not developed an aquatic respiratory system, its adaptation is simple, ingenious and efficient. No need for tanks or scuba. It goes to the surface, captures air from its back legs which comes to be fixed solidly on its fine hydrophobic gray hairs and a bubble is then formed around its abdomen, conferring its silver aspect. This bubble supplies air to its respiratory trachea. This form of air storage having its limits, she has developed a custom-made habitat.
A self-breathing air bell
The Argyronet is the architect of the pond. It weaves its habitat, an inverted bell attached to the plants and impermeable to water. Its appearance has earned it its name, "Argyroneta" meaning "silver web". The properties of this cloth are amazing: it filters gases. The oxygen in the water diffuses into the bell filled with air by the Argyroneta, the carbon dioxide is rejected into the water. The web breathes. But these exchanges do not allow to keep a balance between the different gases, and regularly the Argyronetus must go back to the surface, recover air in the hairs of its abdomen and release it under its bell.
An accomplished swimmer
The powerful front legs of the Argyronetus allow it to unhook itself from the plants and swim with ease. The air bubble, depending on its size, more or less large in males or females, would encourage floating and would influence the agility and speed of each individual. The network of tracheas, extremely developed as in many insects, allows to diffuse the air in all the body, but would also play a hydrostatic role supporting the stability in water.
A hunter on the lookout
A predator, the Argyronetus hunts on the lookout, chasing its prey at full speed, scouring the waters in search of insects, small crustaceans, and even fish. It captures them with its powerful front legs, then neutralizes them definitively with its venom. She cannot consume them underwater, and must therefore bring them back under her bell, or to the surface. Encounters of the Argyronetus with humans, with very distinct habitats, are rare, but cause painful bites, although the venom is harmless.
Males and females, aquatic encounters
The male in the Argyronete is distinguished by its larger size, it joins the female in her bell where mating takes place. The eggs will be laid at the top of the lodge, surrounded by white silk, late spring and summer, the young are born and remain a long time in their shelter. The successive moults will take place in the air, under a bell or on the surface, the young will remain close by or will disperse along aerial threads to explore and colonize new aquatic spaces
Two cousins that walk on water
Large and powerful wetland spiders, Dolomedes live near ponds and calm waters. Powerful, the adults can capture large preys, like damselflies. But also small fish, their fishing technique is unstoppable: they vibrate the water with their front legs and wait for their meal. They make brief appearances underwater, clinging to plants, but generally remain on the surface, leaving the Argyronetus the exclusivity of the aquatic depths.
A pond, calm waters, plants to anchor its web, a little polluted water, some preys: the Argyronet can establish itself, live its adult life for two years, settle its young. And thus perpetuate its species with its so particular way of life. An unsuspected world to preserve.
