Everyone can dive - Spider Topik

The Topik spider (Argyroneta aquatica) is an unusual representative of the animal kingdom. Although its physiology and physiognomy are no different from those of other spiders, it has found a very ingenious way to spend its entire life underwater.

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The fact that Topik, leads an underwater lifestyle, has been recorded for more than 250 years, but only recently has it been established how it takes in and stores the oxygen it needs to survive in such a hostile environment for arachnids.

It turns out that it stores atmospheric air in an underwater bell that it inhabits during the warmer seasons. The whole process of taking and storing air looks as follows: The spider covers its abdomen (on which its respiratory organs – the lung-tracheae – are located) with an air bladder, which it creates, by submerging underwater, air bubbles. This is accomplished by raising the end of the abdomen and the hind pair of legs, between which it forms a special tangle of webbing threads, thanks to which it draws the air bubble, attached to its body, under water. The final stage is to pull the air into the bell and store it.

Scientists Roger Seymour of the University of Adelaide in South Africa and Stefan Hetz of Humboldt University in Germany, discovered that the species, uses its net like gills, allowing it to spend most of its time underwater, rarely surfacing.

In the study, they conducted an experiment on 12 spiders, which they placed in separate containers to examine the oxygen content inside the air bubbles as well as outside. For this study, they used fibre optic cables whose tips were coated with an oxygen-sensitive dye. The results showed that oxygen from the outside diffuses into the bubble, while carbon dioxide travels the other way and thus the Topik replenishes the supply it needs to survive.

Thanks to the external gills formed from their web, the spiders of this species extract up to 70% of the oxygen they need to live from the water. Scientists have never seen any individual need to surface, suggesting that the Topik can stay underwater for more than 24 hours using its ‘webbed gills’.

Scientists are fascinated by the amazing adaptability that this arachnid has developed. This provides great protection against predators that habitually prey on spiders.

Source: newscientist.com
Photo: wikipedia.co.uk