Six-Spotted Fishing Spider

dolomedes triton

The Six-Spotted Fishing Spider (Dolomedes triton) is a remarkable semi-aquatic arachnid found near calm bodies of water across North America. Often seen resting on lily pads or floating vegetation, this agile predator does not spin webs to catch its prey. Instead, it relies on its excellent vision and specialized sensory hairs to detect vibrations in the water surface. Famously capable of walking on water, it can dive beneath the surface to escape predators or chase down aquatic prey, including small fish and tadpoles. It is a fascinating example of adaptation, showcasing how land-dwelling arachnids can dominate aquatic edge habitats.

Habitat: Found near the margins of slow-moving or still freshwater habitats, such as ponds, lakes, marshes, and swamps, where floating vegetation is abundant.

Appearance

This large spider is easily identified by its dark greenish-brown to grey body, adorned with a striking pale white or cream stripe running along each side of its cephalothorax and abdomen. On its underside, it features six distinct dark spots, which give the species its common name. The abdomen also boasts several pairs of small white spots. Females are significantly larger than males, with a body length reaching up to 2.6 centimeters, and long, robust legs that can extend the total span to over 6 centimeters.

KingdomAnimaliaPhylumArthropodaClassArachnidaOrderAraneaeFamilyDolomedidaeGenusDolomedes

Six-Spotted Fishing Spider

Interesting facts

Despite their large size and aquatic hunting habits, these spiders are harmless to humans and will typically dive or swim away when approached.

Female fishing spiders are devoted mothers, carrying their large, silken egg sac in their jaws until the eggs are ready to hatch, then building a protective nursery web for the spiderlings.

They can remain submerged underwater for over half an hour, utilizing an air bubble trapped on their abdomen like a tiny scuba tank.

Special abilities

Uses hydrophobic hairs on its tarsi to distribute weight, allowing it to skate rapidly across the water's surface without sinking.

Can submerge underwater for up to 30 minutes by trapping a silvery bubble of air around its body using specialized water-repellent hairs.

Employs sensitive leg hairs called trichobothria to detect ripples made by struggling insects or tiny fish on the water's surface from several inches away.

Measurements & details

Length: 1+ cm
Weight: 0.001+ kg
Lifespan: 1+ years
Top Speed: 3 km/h
Clutch Size: 200+
Incubation: 14+ days

Diet & Feeding

An opportunistic ambush predator that feeds on terrestrial insects that fall into the water, as well as small aquatic organisms.

Age differences: Juveniles feed mostly on small aquatic and terrestrial insects, while mature adults are large enough to capture small vertebrates like fish and tadpoles.