Dolomedes

Dolomedes is a genus of spiders belonging to the family Pisauridae, commonly known as fishing spiders or raft spiders. These spiders are characterized by their large size and their ability to live on or near water. They are semi-aquatic and can often be seen walking on the surface of water or resting on vegetation at the water's edge.

Dolomedes spiders possess a remarkable adaptation that allows them to stay on the water's surface without sinking. They are covered in hydrophobic hairs that trap air, creating a layer of air bubbles around their bodies. This buoyancy, combined with their strong legs, enables them to move across the water with ease. They can also dive beneath the surface to escape predators or to hunt. When submerged, they can remain underwater for extended periods, sometimes up to 30 minutes, by trapping air in a silken web or in hairs on their abdomen.

Their diet primarily consists of aquatic insects and small fish, though they are opportunistic predators and will also consume other terrestrial invertebrates. They hunt by waiting patiently on the water's surface or on vegetation, using their sensitive hairs to detect vibrations from prey. When prey is detected, they can quickly dart out to capture it.

Dolomedes spiders are found in various parts of the world, including North America, Europe, and Asia. They typically inhabit wetlands, ponds, lakes, and slow-moving streams. Different species within the genus have specific habitat preferences, but a connection to water is a defining feature of the group. Their large size and striking appearance have led to them being a subject of interest for arachnologists and nature enthusiasts alike.