Dock or Fishing Spider
The Silent Hunters of Ontario’s Waters: Dock or Fishing Spiders
Not all spiders stay on land! Dock Spiders, aka Fishing Spiders (Dolomedes) have mastered the art of hunting on and even under the water.
These large, nocturnal arachnids are among Ontario's biggest spiders, with females reaching up to 3–3.5 inches (8–9 cm). They are often seen gliding across lakes, docks, and boats in search of prey. Their specialized velvet-like hairs repel water, allowing them to stand, run, and even dive beneath the surface without sinking.
Unlike traditional web-weavers, Dock Spiders rely on stealth and speed. They patiently wait for the slightest ripple in the water, signalling the presence of an insect or even a small fish. In an instant, they race across the surface, using their long legs to glide effortlessly before grabbing their unsuspecting prey.
But their hunting skills don’t stop at the surface! These spiders can dive underwater thanks to their specialized lungs, which allow them to breathe while submerged. However, there’s a catch: the air trapped in their lungs makes them float, so they must cling to rocks or plants to stay beneath the surface long enough to ambush their prey.
Female Dock Spider with Egg Sac
Beyond their impressive hunting abilities, female Dock Spiders display remarkable maternal instincts. When carrying their large egg sac, they hold it in their fangs or front legs, ensuring its safety until the young spiders are ready to hatch. Instead of leaving the sac exposed, the mother chooses a secure location, surrounding it with a protective web to shield it from predators. She then stands guard, ensuring her offspring remain safe until they emerge. Each egg sac can contain up to 1,000 baby dock spiders, making her dedication to their survival even more impressive.
Dock Spiders come in various shades of brown, black, and cream, with some species displaying pale stripes or dotted patterns along their bodies. Their camouflage helps them blend into their surroundings, making them difficult to spot until they make their move.
If you’ve ever relaxed by a dock or lake and noticed a large spider darting across the water, chances are you’ve encountered one of Ontario’s most fascinating hunters. With their unique adaptations, stealthy hunting techniques, and devoted maternal care, Dock Spiders prove that not all arachnids are bound to land.