Mostly, many people who struggle with arthropods feel comfortable in water since they are confident that spiders cannot live in water. If you are one of them, then you are not familiar with the swimming spiders, known as the diving bells. These spiders spend most their lifetime underwater. You might be surprised, but yes, there is such a creature as underwater spiders.
Diving bell spider is among the few species of spiders that are known to live entirely under water. It is a member of the genus Argyroneta, and when it is outside water, its color ranges from mid to dark brown, but the hairs on its abdomen gives it a dark gray appearance.
How they do it
This species of spiders is quite like other species such that it breathes air just like the other types. The spiders make a web cocoon with silk which they fill up to create a bubble full of air which they can breathe when underwater.
When submerged in water, there is an air bubble trapped by the dense layer of hydrophobic hairs on the legs and abdomen, and this gives the belly a silvery appearance. The spiders can live for up to two years. Due to their inbound life under water, the spiders can make use of the oxygen, and they only need to come out of the water about once in a day to replenish their air supply.
Swimming spiders are found in ponds of the central and northern Europe and in some parts of Asia. It is the only spider species known to spend its life wholly underwater. The spider does regular spider activities like laying eggs and mating. Using the silk thread, it is easy for it to trap unsuspecting prey since when anything touches the threads it furiously gets out and bites with its fangs.
The look of this species arises from the genus Argyroneta and the Greek word argyrols which mean silver and net. Spiders from both sexes make a diving bell web which is also used for molting and digesting prey. The large female bell is the only one used for mating and raising the young ones. Females spend most of the time in the bells waiting to catch any prey that comes near the bell. The male bells are smaller than the female ones and do not require regular replenishment.
Before mating, the males build a bell adjacent to the female bell and then spins a tunnel that connects the two bells and mating takes place in the females’ bell. The female then creates an egg sac within her bell and lays about 30 to 70 eggs.
The diving bells are constructed irregularly using sheets of silk and some protein based hydrogen which are submerged between water plants and inflated with air from the underside surface by the builder. Research has shown that there is high gas diffusion between the spider’s aquatic environment and the diving bell and this helps them to survive.
Silk is waterproof, and it allows for gas exchange around the surrounding water. It allows for net diffusion of oxygen in the bell and carbon dioxide out of the bell due to the difference in partial pressure. Taking in oxygen and breathing out carbon dioxide keeps the concentration gradient-balanced but the gradual diffusion of nitrogen from the bell makes the air bubble to shrink, and for this, it must be replenished by the spider.
The larger the spider, the bigger the bubble produced and the higher the oxygen conductance. However, the spiders can enlarge their bells depending on the high oxygen demands in a low aquatic environment. They do this by voluntarily enduring the low oxygen conditions inside the bell, and in return, the bell is enlarged when the level of P (O2) drops below 1k Pa. This replenishment process is however not common, and it does not need to occur for several days. The system is referred to as water aqua-lung of air bubbles and it is well regarded as an inorganic grill.
The aquatic spiders are found in freshwater streams and ponds. They can survive in water for an extended period due to the silk structure as it helps to retain the oxygen supply. The structures come in a range of sizes the female ones being large since they put a lot of effort building and maintaining them. The male spiders are larger and active than the females. This is because the male hunting styles require a lot of energy to overcome water resistance and deal with the buoyancy of the mobile air supplies.
The males are known as better divers due to the size of their legs. They feed on aquatic insects and crustaceans like the mosquito larvae. However, the spiders themselves are preys to frogs and fish.