In the days before scuba tanks, people used to explore the underwater world with the aid of diving bells. These large open-bottomed chambers were dunked into the water, and divers used the air trapped inside them to breathe. The bells have been around since at least the time of Aristotle, but in the rivers and lakes of Europe, one animal has been using similar structures for far longer – the diving bell spider.

The diving bell spider is the only member of its group to spend its entire life underwater. But it still needs to breathe air, and it does so by building its own diving bell. First, it spins a dome-shaped web between underwater plants. Next, it rises