Diving bell spider
Argyroneta aquatica
— Where the name comes from
Argyroneta is “silver-spinner”, from árgyros, silver, and nêin, to spin: the bell of air the animal builds underwater catches the light and looks like a bubble of polished metal. Aquatica states the only truly exceptional thing, which is that a spider — an air-breathing animal — has chosen to spend its whole life submerged. It is the only one in the world that does.
— Facts
- Group
- Arachnids · Arachnida
- Order
- Spiders
- Habitat
- Clear still water rich in submerged plants
- Range
- Europe and northern Asia
- Size
- 8–15 mm; the male larger than the female, a rare case
- Diet
- Insect larvae, crustaceans, small tadpoles
- Lifespan
- 2 years
— Characteristics
- 01
It builds a silk bell underwater and fills it with air.
- 02
It carries air down from the surface trapped among its abdominal hairs.
- 03
It eats, moults, mates and lays its eggs inside the bell.
— What sets it apart
The bell is not merely a tank: it is a gill. Oxygen used up inside is replaced by diffusion from the surrounding water, and nitrogen slowly leaves — measurements with microelectrodes have shown that the spider can stay in the bell for more than a day without surfacing, provided the water is well oxygenated. It must still come up occasionally to make good the lost nitrogen. It is the only spider in the world that lives entirely underwater, and the only one in which the male is larger than the female: he needs it to swim better, having to go and find her.
