The Announcements
Rescheduled: our Annual Banquet is postponed to Wednesday, March 1, 2023 at Texas Discovery Gardens. If you have not RSVP’d yet and would like to attend the March 1 banquet/chapter meeting, you can do so HERE. If you have already registered, your RSVP simply carries forward (an Eventbrite email went out to you January 31). Please view the full set of January announcements by clicking here. Further activities are listed on the chapter calendar. Opportunities and contacts, websites, and other details are available here.
Highlights of the Meeting
Ice-schmice. A big shout out to everyone involved with quickly moving this month’s meeting from an in-person banquet to an online training meeting. Programs, Communications and Banquet Teams – thank you!
Spiders on the Prairie
Many thanks to naturalist, photographer and arachnid advocate Meghan Cassidy for a fascinating look at spiders found in North Texas. Drawing on her excellent photographs, she wove together basic arachnid taxonomy, ecology and natural history with common families. Special thanks for presenting on such short notice.
Class Arachnida includes spiders, harvestmen, scorpions, pseudoscorpions, vinegaroons, camel spiders, ticks & mites. Meghan reviewed the orders containing each of these before focusing in on her particular interest: the smaller spiders comprising the order Araneae.
The term “daddy long-legs” points out the problem with common names, as it can refer to harvestmen and cellar spiders. Meghan dispelled the widely held myth that these are extremely venomous spiders (that don’t bother humans because of their tiny fangs). Harvestmen, as scavengers, have neither fangs nor venom (though they have a chemical defense that would taste and smell bad to us), and are actually not even spiders. Cellar spiders truly are spiders but are not especially venomous.
Moving to the order Araneae, Meghan gave examples of sexual dimorphism. Spider females generally are considerably larger than males, while males of some species employ bright coloration and dance to attract females.
Showing that spiders exhibit maternal care, Meghan discussed how female wolf spiders carry egg sacs through hatching and then carry young spiders until they are ready to hunt on their own. Nursery web spiders build a silk and vegetation tent to protect the egg sac and young spiders. She discussed some of the spider egg sacs we may encounter and how pattern, color and arrangement help identify genera, such as the basilica orb weaver’s chain of egg sacs.
Meghan used how spiders hunt to highlight different families in the Araneae. She pointed out that spiders make seven kinds of silk to make various webs, traps, sleeping sacs and egg sacs, and that some do not produce webs to hunt.
The yellow garden spider provides a familiar orb weaver example that builds a characteristic web. Meghan encouraged us to look carefully at their webs, both to note the zigzag-patterned stabilimentum and also to find kleptoparasite robber spiders.
Meghan emphasized two of the ecological roles spiders play. First, they provide pest control in nature and in our homes. Second, they are a food source to a wide variety of insects, birds and reptiles. Some mud dauber wasps are specialized to immobilize certain spiders and seal them in nests to feed larvae as they develop.
She gave two examples of mimicry. One is the bird-dropping spider that uses camouflage both to hunt and avoid predation. The ant mimic jumping spider is difficult at first to distinguish from an ant, until it jumps or releases silk.
Her favorite North Texas orb weavers are the spiky ones, particularly the spiny-backed orb weaver. These are often brightly colored, in orange, red, yellow or white, making them a little easier to spot.
The last spiders Meghan addressed were the two medically significant ones in our area. The brown recluse gets something of a bad rap as skin lesions are sometimes misdiagnosed as recluse bites. Because of their necrotic venom, their bites should be taken seriously. Meghan advises seeking medical help, particularly if one sees the spider that bit them.
The black widow’s neurotoxic venom may be less dangerous than the brown recluse, but still can have serious effects.
In closing, Meghan encouraged us to add arachnid observations to iNaturalist. With plenty of arachnologists on the app, simply identifying as “spider” is a sufficient start. Record at least an overall image from above; adding a view from the side and of the eye arrangement helps with classification. One caution for field work: while Meghan has handled hundreds of spiders without being bitten, she advises against contact until one really knows their spiders.
Meghan offered to lead a spider walk this year, so stay tuned for that posting.
Going Deeper: Field Guides
The primary guide Meghan recommends: Spiders of North America, Sarah Rose
Also: Spider Silk, Brunetta and Craig; Amazing Arachnids, Jillian Cowles
Biology of Spiders, Rainer Foelix; Spiders in Ecological Webs, D.H. Wise
Myth of the Brown Recluse, Rick Vetter; Private Life of Spiders, Paul Hillyard
Contact information: Meghan Cassidy or on iNaturalist @wildcarrot
The full recording of this meeting is posted here.
Thanks to our guests and members for participating in this month’s meeting. I hope all feel welcome at NTMN.
Take care,
Scott Hudson
President
North Texas Master Naturalist