Spider of the Month – January 2020

Our spider of the month is this fishing spider (Nilus sp.) found by Benanta Smit.

She found the spider in her pool, and shortly after she fished her out, it started moulting. Unfortunately the spider had a mismoult, and her four left legs were stuck in her exuvia. Benanta managed to free two of the legs, but the next morning the spider self-amputated those legs, leaving her with three right legs.

Benanta took it on herself to care for the spider until her next moult, which usually takes at least a month. This spider, however, moulted 13 days later, and regrew her four left legs. This was after managing to only feed her two flies. Strangely enough, while regrowing the fourth right leg, she lost her third right leg, so she has seven legs now, which is still beter than three.

While spiders can easily adapt on two or three legs, they are certainly at a disadvantage, especially if they depend on running down their prey, and even more so if they depend on the surface tension of water, which will be quite difficult if they only have legs on one side.

Fishing spiders are in the nursery-web spider family (Pisauridae), and as the name suggests, they spend most of their time near water bodies, hunting aquatic animals like tadpoles, small fish, and any other animals that might disturb the water surface that they carefully monitor, such as a fly struggling in the water.

While some nursery-web spiders capture their prey in webs, fishing spiders are among the free-living genera, but like all nursery-web spiders, they will carry their egg sac in their mouth parts, and when the eggs are close to hatching, they will spin a special web, deposit the egg sac there, and the hatchlings will stay in this “nursery web” until they are old enough to disperse.

The spider of the month doesn’t always have to be a rare spider; sometimes it just needs a good story behind it. Thanks to Benanta, this spider has a much better chance at survival, and her story has intrigued quite a few people on this group, which is why we’ve chosen her as the spider of the month.