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Dolomedes triton

By Lindsay Lane

Geographic Range

The fishing spider can be found in East Texas, the coastal New England states, and south along the Atlantic coastline to Florida, and as far west as North Dakota and Texas. This spider can also be found in the moist environments of Central America and South America.

(Jackman 1997)

Habitat

Dolomedes triton can be found primarily around lakeside vegetation, boat docks and other structures near a body of water.

(Jackman 1997)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams
  • coastal

Physical Description

Large and boldly marked, the fishing spider closely resembles the wolf spider, although it has eight eyes equal in size, three tarsal claws, and it lacks a cribellum, which is a spinning organ found just in front of the spinners. Coloring is grey to brown with light areas and light spots on its brown abdomen. On average, length is 17-26mm for females, and 9-13mm for males. The length for females can sometimes exceed 30mm.

(Jackman 1997, Preston-Mafham and Preston-Mafham 1996)

  • Range mass
    1.0 to 1.5 g
    0.04 to 0.05 oz
  • Average mass
    1.0 g
    0.04 oz

Reproduction

Males must court females carefully, as they may be eaten if the female is sufficiently hungry and/or the male fails to successfully communicate.

After mating and fertilization, females spin a silk sack to carry their eggs in, and carry them around in their front jaws until just before the eggs hatch. At this time, the female will place the eggsac between leaves in a shelter made especially for this occasion. The female fishing spider then guards her eggs until after they have hatched, and then guards the young fishing spiders until they are ready to move away on their own, usually about a week after they have hatched.

(Jackman 1997)

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)

Behavior

The fishing spider is diurnal, so it hunts during the day or opts to sit still for hours on end, depending on whether it is stimulated by prey. This species of spider makes use of its very good vision when diving to capture its prey, as opposed to web-spinning spiders which use stimulation on the web to capture prey.

The spider is also sometimes seen dabbling its front legs on the surface of water in order to lure fish.

(Preston-Mafham and Preston-Mafham 1993, Wise 1993)

Food Habits

In order to capture its prey, the fishing spider makes use of concentric surface waves on still water to pinpoint the exact location of the prey, up to 18cm away. Once it homes in on this locale, it dives beneath the water, as deep as 18cm below the surface, to capture the prey. Fishing spiders feed on insect larvae, tadpoles, and small fish, eating up to five times its own weight in one day.

(Ewing 1989, Prestono-Mafham and Preston-Mafham 1993)

Economic Importance for Humans: Positive

The fishing spider, like all species of spiders, is important in keeping the insect population of the world under control.

(Jackman 1997)

Conservation Status

These spiders are not given any special conservation status.

Other Comments

The fishing spider can stay underwater up to 45 minutes, using air trapped in the hairs on its body to respire. It can also exceed 3cm in length.

Although its feeding habits are unique to the species, the fishing spider does not have a very high success rate at catching prey, which it does successfully only 9% of the time. This can be attributed to the spider having difficulty distinguishing between prey-generated ripples and those made by falling leaves, twigs, and the like.

Accidental contacts are more successful at a rate of 16%.

(Preston-Mafham and Preston-Mafham 1996, Wise 1993)

Contributors

Lindsay Lane (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

coastal

the nearshore aquatic habitats near a coast, or shoreline.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

native range

the area in which the animal is naturally found, the region in which it is endemic.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scrub forest

scrub forests develop in areas that experience dry seasons.

References

Ewing, A. 1989. Arthropod Bioacoustics: Neurobiology and Behaviour. New York: Cornell University Press.

Jackman, J. 1997. A Field Guide to Spiders and Scorpions. Houston: Gulf Publishing Company.

Preston-Mafham, R., K. Preston-Mafham. 1993. The Encyclopedia of Land Invertebrate Behaviour. Cambridge: MIT Press.

Preston-Mafham, R., K. Preston-Mafham. 1996. The Natural History of Spiders. Wiltshire: The Crowood Press.

Wise, D. 1993. Spiders in Ecological Webs. New York: Cambridge University Press.

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