Some spiders have developed spectacular adaptations to the aquatic environment, and Trechalea extensa is a prime example.
Although they suffer from an unfairly unflattering reputation, spiders are fascinating beasts in many ways. Far from the species that weave webs in the corners of houses, there are also many species that exhibit unique and utterly fascinating behaviors. This is the case of extensive trechaleaa species that escapes its predators… by diving!
This is a point which may be surprising. Because even the so-called “semi-aquatic” species are simply not equipped with gills to extract oxygen from the water. They certainly feed on larvae and small freshwater fish in the tropics; but they all use specific hunting techniques that allow them to do so without risking drowning.
For naturalists, this is a real blessing. These spiders often exhibit quite spectacular adaptations to their environment that manifest themselves in some very interesting behaviors. And this is the case of extensive trechaleaaccording to this study identified by Futura.
A funny spider with integrated spacesuit
Researchers have found that she tends to dash through the water at full speed when approaching humans. She then remained submerged for a good half hour. And researchers have determined the origin of this sleight of hand; to achieve this, she can count on a real scuba which appears spontaneously at the moment of the dive.
Indeed, this species has many hairs which have the effect of creating a completely impermeable surface; we then speak of a hydrophobic surface. And since this surface flatly refuses to come into contact with water, this materializes by capturing an air pocket around the spider.
This little suit works admirably well. It allows the spider to stock up on oxygen long enough for a predator to lose interest. A very interesting ability in the unforgiving tropical jungle where she resides. And this intermediate layer also serves as a down jacket to prevent extensive trechalea to suffer from hypothermia in case she had to rush into a pond too chilly for her taste.
A surprising evolutionary path
But this mode of defense also raises many questions. Because for animals like spiders, which are by definition quite sedentary, fleeing one’s territory is not without consequences. This implies leaving one’s home, and therefore a possible unsupervised offspring. Moreover, the aquatic environment is also not an inviolable haven of peace. It also involves risks, and some predators are not afraid to venture there.
At first glance, it doesn’t look like not really an optimal solution in terms of natural selection. Lesearchers are curious to find out what selection pressures encouraged it to take this evolutionary path. They will therefore continue to be interested in it.
A small player compared to the queen of the category
But despite these prowess, extensive trechalea is not the greatest specialist in this environment, however. This title unquestionably belongs to the argyronete; a species that isn’t just content to hide in the water… but has made it its own exclusive living environment, while it also lacks gills. A feature that is currently unique in the scientific literature.
Like extensive trechalea, Argyroneta aquatica also takes its oxygen on board. But his solution is even more elaborate. Here, it is not the hairs, but the fabric itself which acts as a hydrophobic surface. It therefore works like an oxygen balloon, a little like the bell divers of old. The spider simply rises to the surface once in a while to fetch a boatload of fresh air by catching a bubble around its posterior, just like the spider does. extensive trechalea.
Otherwise, it spends its entire life cycle underwater. This canvas also serves as a dining room since this is where this formidable swimmer comes back to taste her prey. It also serves as a nursery; this is where the argyronet breeds and babies will be born. So many elements that remind us of the extent to which spiders are fascinating living beings.
The text of the study is available at this address.