The Mississippi Valley Field Naturalists January Nature Talk on January 18 was entitled “Eat Prey Love; The Secret Lives of Spiders”. The talk was presented by Dr. Catherine Scott, an arachnologist and behavioural ecologist. Catherine provided a convincing argument that there are far more reasons to be fascinated by spiders than to fear them.
The evening opened with a slight modification to our usual proceedings. Cliff Bennett and Ron Williamson very ably filled in for Ken Allison for the sightings portion of the meeting. This was followed by Catherine’s presentation, beginning with the definition of a spider, which is not an insect. It is one of 11 or 12 orders of arachnids (one is in dispute) and has eight legs and two main sections. Spiders are covered with sensory hairs which provide them with their ability to hear, touch and taste. Spiders are unique in having abdominal silk glands. There is a variety of different glands each with different kinds of silks, depending on the family or group of spiders. They serve functions such as: sticky webs for prey capture, strong and flexible drag lines, safety lines, prey swaddling and egg sack construction. Catherine highlighted some of the amazing shapes and sizes of webs that spiders create and explained how each is used.
The earliest ancestors of spiders are over 400 million years old and there are now more than 50,000 species world-wide, with close to 1,500 in Canada. They are found in almost every terrestrial habitat, including deserts, arctic tundra and some aquatic ones. Catherine described the amazing ways spiders engage in prey capture as well as how they defend themselves against their predators, with photos to accompany her examples. She also described her research on black widow spiders where it was found that a male could sense a female up to 60 meters away. A number of spiders have fascinating mating habits and some examples were given, as well as instances of excellent mothering (though they are not always so kind to their mates!).
She quoted a study showing that spiders were found in 100% of homes and almost 80% of rooms. While all but two species of spiders here have venom, Catherine stressed that they do not bite humans! But spiders are very important, particularly in gardens and agroecosytems, where it has been shown that numbers of crop-eating insects are reduced just by the presence of silk. It is estimated that spiders eat 400-800 million tons of insects globally per year. A species of spider in Africa is specialized to feed on mosquitos carrying malaria. Spiders are also an important food for birds, lizards, toads and others. She concluded her talk by noting that spiders are not only extremely useful, but beautiful and fascinating!
Catherine is now studying candy-striped spiders and is asking those interested to contribute to a citizen science project by contributing photos of these spiders to iNaturalist. More information is available on her website: www. spiderbytes.org.
The next meeting on February 15 is MVFN’s Members’ Night followed by the Annual General Meeting. Join us for a photo presentation of the canoe outings and canoe camp, the latest conservation efforts from the Mississippi Madawaska Land Trust and an extended sightings talk with Ken Allison.
Submitted by Chris Baburek