Ahead of our guided spider walk on July 13th, we’re profiling a few of the most common spider species of the Oak Ridges Moraine. You’ve probably come across a few of these species over your lifetime without even realizing it! Spiders are small. They’re often difficult to identify to a species level (scientists often have to study their genitals with a microscope to confirm an ID). They’re a lot less popular with the general public than birds or mammals. Despite the negative cultural associations we have with spiders, they’re an essential part of the ecosystems they inhabit. Spiders are predators of smaller invertebrates and an important source of food for birds, amphibians, and even other spiders. Let’s take a moment to appreciate these arachnids and challenge some of our preconceived notions about them. The next time you see a spider crawling around your house, think twice before you squish it!
· Bold Jumper (Phidippus audax)
This species is sometimes known as the Darling Jumping Spider. Bold Jumpers are common throughout North America. Humans have accidentally introduced them to a number of spots across the world including the Netherlands, California, the Azores, and Hawaii. Their mouthparts (chelicerae) are iridescent green. They don’t build webs, relying on their excellent vision for hunting. Insects and other spiders are their favourite prey. They’re largely solitary but come together for elaborate courtship displays. Males perform a “dance” where they move their legs and front appendages (pedipalps). Mating can last for over two and a half hours. The Bold Jumper is often found in forested habitats.
· Yellow Garden Spider (Argiope aurantia)
This common spider species ranges widely throughout North America from Canada to Nicaragua. The yellow patterning on their legs and abdomen is distinctive. They often build their webs in fields, tall grass, gardens, and on the sides of buildings. They have a mild venom which isn’t dangerous to humans. Largely insectivores, in some parts of their range, they eat small vertebrates including lizards! Their webs have a peculiar, zig-zagging structure in the centre called a stabilimentum. Scientists still aren’t sure why some spiders add these to their webs. In the past, they thought that it aided structural stability (hence the name) but this doesn’t seem to be the case. Stabilimentums may help to make the webs more visible so that birds and other animals don’t accidentally damage them.
· Dark Fishing Spider (Dolomedes tenebrosus)
The Dark Fishing Spider is one of the largest spiders in the Oak Ridges Moraine. Including their legs, they can be up to 9cm in length! Despite their name, fishing spiders aren’t always found by water. Interestingly, this species doesn’t build webs, preferring to stalk their prey. They spend most of their life walking around the ground, where their mottled brown colouration helps to camouflage them. Fishing spiders have excellent vision, which they use to hunt insects and other invertebrates. The males can only mate once and die soon afterwards. Females will often eat their bodies. Romantic!
· Goldenrod Crab Spider (Misumena vatia)
The Goldenrod Crab Spider has a fascinating hunting strategy involving mimicry, camouflage, and colour change. They eat pollinating insects that visit flowers like bees and ants. In order to ambush them, the Goldenrod Crab Spider will change its colour to match the surrounding flowers. Sometimes, they position their bodies to imitate a flower. Other times, they‘ll blend into a flower by matching its colour. They use their keen vision to spot their prey and strike it. Their abdomens are transparent. This allows them to sometimes take on the colour of their prey after eating it! Goldenrod Crab Spiders will guard their nests, helping to keep their eggs safe from predators. In North America, they range from Panama and the Caribbean as far north as Alaska. This species is found throughout Eurasia as well, catching wasps and flies from Ireland to China.
· Tan Jumping Spider (Platycryptus undatus)
Also known as the Familiar Jumping Spider. This species is often found crawling along the bark of trees. They’re extremely well camouflaged in this context, closely resembling a lichen. They have eyes around the length of their heads, giving them nearly 360 degrees of vision. They perform a unique courtship ritual in which the male taps and waves his legs for a prospective female. The Tan Jumping Spider doesn’t build a web to catch its prey. Instead, it ambushes them and (living up to its name) jumps on them. Amongst the most intelligent arachnids, jumping spiders have been the subject of studies by neurobiologists.