Facts about the Fishing Spider

The fishing spider or Dolomedes, belongs to the family of Pisauridae. They can be found almost anywhere in the world, from North America and Europe through to New Zealand, with over 100 species altogether. They are a large species of spider which also includes the raft spider, dock spider, wharf spider and the nursery web spider.

The fishing spider is quite aptly named. While they are known to eat the odd small fish, it’s their method of hunting for prey which is more akin to fishing rather than their desire to catch fish.

Most fishing spiders are semi-aquatic and not particularly adventurous so they are often found near water by swamps or ponds and river banks. Some species, such as the dark fishing spider found in North America, can wander away from water and into dry places such as woods and even enter houses.  

The fishing spider is often confused with the wolf spider due to its large size. But apart from this, they are quite easy to recognize. Their colorings vary from country to country but generally their bodies are light brown with a distinctive cream stripe down the side and their thickset legs are marked with dark colored rings. Their eight eyes are distinctively arranged in two rows near to the front of their head. Females are bigger than the males and can have a leg span of up to three inches with males only around half their size.

Their entire body and legs are covered with short, velvety like hairs which repel water and effectively waterproofs them. This enables the fishing spider to sit beneath the water’s surface where air becomes trapped around its hairs, forming a silver film around the entire body.  This film of air allows the spider to breathe while under the water as well as keeping it afloat.

Fishing spiders are nocturnal and actively hunt during the night. As with all spiders, they eat insects but are capable of catching minnows, a tiny type of fish and will eat tadpoles, frogs or even slugs. They don’t spin webs to catch their prey like the majority of spiders. Instead, the fishing spider will sit at the water’s edge, holding onto vegetation on the ground with its back legs, while resting its front legs on the water’s surface. In this position they’ll wait to detect any vibrations from the water’s surface.

Because they hunt at night, their eyesight isn’t their predominant sense. Instead, they rely on the highly sensitive hairs on their legs to detect not only the distance of their victim but also how big it is. Once it senses the vibrations on the water, it with either pop up completely dry if it was submerged, or run across the surface of the water to grab the prey to subdue it with its venom.

At mating time the male fishing spider needs to watch out since females often attempt to eat the male once the deed is done. To try and prevent such a dismal outcome, the males may offer a food source such as a fly, to try and appease the female hunger.

The female fishing spider carries her silk egg sac around in her chelicerae (large fangs) until ready to hatch. When the time comes she will move onto dry land where she will build a small nursery web among leaves into which she will place the egg sac. While she’s waiting, she’ll spend most of her time sitting nearby, rigidly guarding her precious unborn brood. A single egg sac can contain up to 1400 eggs.

Although the fishing spider isn’t considered dangerous for humans, being such a large spider its fangs are capable of biting through human skin. However, unless they bite someone who happens to be allergic to spider venom, the worst that should occur is a stinging pain at the site of the bite.

The fishing spider is certainly unique among its peers with its ability to walk or run on water. And as with all spiders they provide a useful service to humans by preying on disease carrying insects such as flies or mosquitoes. However, they are a particularly large spider and for those with a fear of these eight legged beasts, it’s a good thing they prefer living by the water and not in our homes.