Living Sanibel: Crash course on spider species
Golden Orb Weaver (Nephila clavipes)
A very impressive and large spider, the golden orb weaver is arguably the largest spider on the islands. Prior to the arrival of Hurricane Charley in 2004 and Wilma in 2005, it was always possible to find multiple golden orb weaver webs in the power lines running north along Dixie Beach Blvd. After the hurricanes blew through, most of these massive webs were destroyed and the golden orb weaver has yet to fully recover from the storms.
While it is a venomous spider, it seldom bites humans and will do so only if it is pinched. The ensuing sting is relatively harmless and leads to a slight redness and localized pain. It looks far more deadly than it really is. Its web, which can exceed a meter in diameter, is comprised of beautiful yellow, golden threads that have six times the tensile strength of steel.
Recently the silk of this spider has been used to help in mammalian neuronal regeneration, connecting neurons in the human body from where they were severed. Further research is being done with this spider’s amazingly strong silk to see what further scientific uses might be made of it.
This large spider is preyed upon by a handful of mammals, snakes and reptiles. It catches any number of flying insects, including dragonflies, in its large web and quickly subdues them with its toxin. In Australia an even larger relative of the golden orb weaver is known as the bird-eating spider. It builds a web so large and strong it captures small, warbler-size, birds and subdues them with its venom.
Daddy Longlegs (Family Leiobunidae)
Although they belong to the class of arachnids, daddy longlegs are not true spiders. Recent DNA evidence indicates they are more closely related to ticks and mites than to spiders. They belong to the larger order Opiliones, which is further divided into four suborders.
Worldwide there are more than 6,400 identified species of harvestman spiders. Most scientists are convinced the actual number of these insects will exceed 10,000 species, since hundreds are being discovered and added to the order every year.
The daddy long legs spider is venomous but its mouth is too small to actually bite a human. In the wild they are omnivores, feeding on small insects, plants, fungi and carrion. Like a handful of reptiles and fish species, some daddy longlegs are parthenogenetic, meaning they are capable of a-sexual reproduction. This attribute is more common in the phylum Arthropoda than in any other phylum. Parthenogenetic reproduction is unknown of in mammals.
There are quite a number of insects, birds and reptiles, including toads, that feed on daddy longlegs. They also suffer high mortality at the hands of internal parasites, which they ingest when feeding on dead organisms, bird dung and other fecal matter. Several cave dwelling species are currently considered endangered or threatened.
This is an excerpt from The Living Gulf Coast – A Nature Guide to Southwest Florida by Charles Sobczak. The book is available at all the Island bookstores, Baileys, Jerry’s and your favorite online sites.