Spiders (Class Arachnida)
Spiders are a common sight in Canadian homes and offices. They are usually found in the corners of rooms and ceilings, closets, dark crevices, basements, garages and gardens. The most common spiders found in and around buildings include house spiders, wolf spiders, cellar spiders, fishing spiders, and (much less often) black widow spiders.
Spiders have an unsegmented body with two main divisions and a total of eight legs (four pairs). Spiders will often produce silk which can be used to build webs or nests to catch prey, cocoons for their eggs, to wrap and immobilize their prey and even for transportation.
Most spiders prey on insects, many of which are pests. Once their prey becomes tangled in the web, the spider immobilizes it by wrapping it in more silk and then injecting venom to paralyze it. Later, the spider injects a predigestive liquid and sucks out all the nutrients from its prey. Not all spiders are web spinners and there are many types of spiders that use different strategies to catch their food.
Types of spiders found in Canada
Wolf spiders hunt for their prey instead of spinning webs and waiting. These spiders can be as large as 3 cm (just over 1 inch) in length and have a dark brown colour. Wolf spiders are usually found on the ground in grasslands, woodland floors, beaches and gardens. They mostly feed on insects. They are most likely to enter homes and buildings in the fall as they look for warm places for shelter.
Fishing spiders may look similar to wolf spiders but they have a different eye pattern. The adults can reach up to 7.5 cm (3 inches) in width. They are typically found near cottages and waterfronts, especially around rocks near the shoreline. These spiders forage for their prey. Unlike wolf spiders, which carry their egg sac behind their body, fishing spiders carry their egg sac under their head and front thorax (upper body).
Cellar spiders have very long legs and build their webs in the corners of cellars or cool and damp basements. Common names for cellar spiders include "daddy longlegs" and "skull spider". The legs of these spiders are about five to six times longer than the length of their bodies. Female spiders may have a leg span reaching as much as seven centimeters, and males are slightly smaller.
Cellar spiders can be confused with another spider-like relative commonly known as the harvestman or daddy longlegs. The harvestman does not have two distinct body parts like true spiders, nor do they have silk-producing glands. However, with their four pairs of long slender legs, they may look like spiders at first glance.
The house spider is commonly found within the house. The house spider varies in colour from dirty white to nearly black, with visible markings on its body. Its first pair of legs is almost three times the length of its whole body. It builds webs in dark corners, under furniture and anywhere insects might be caught.
Black Widow spiders
There are a few black widow species that can be found in Canada, mainly in the southern parts of the country, but they are not common. It is shiny black, with a distinctive red hourglass-shaped mark on the underside of its stomach. It spins a small, silk web close to the ground and is found in secluded places like garages and sheds, or under rocks or fallen trees when outside. It is not aggressive and prefers fleeing when disturbed, so it will only bite to defend itself.
- 2 body regions: cephalothorax (head and thorax fused) and abdomen
- Four pairs of legs
- Tend to be found in secluded, undisturbed areas
- Largely active at night
- Some spiders use silken webs to capture their prey
- Others are active hunters that explore their environments for food
- Still others are passive hunters that ambush their prey
- Nearly all spiders are venomous, but most are not dangerous to humans
- Female lays 2 dozen to several hundred eggs in egg sac(s)
- Most live for 1 to 2 seasons, although a few can live as long as 20 years
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