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Daddy long legs
(Order Opiliones, Family Phalangiidae) Photography by Nancy T. text by Jerry Cates
Within the large group of jointed animals with eight legs is an order known, today, as the Opiliones. These are the harvestmen, which are not spiders but which, from a distance, look like spiders. Except for having eight legs, however, a close examination reveals major differences. They have no silk or venom glands, and--though with some minor exceptions--their mouth parts cannot pierce human skin. Instead of two body parts they have one. And instead of six or eight eyes, they have two. Unlike spiders, they excrete an odorous musk for defensive purposes. They prey on other arthropods and scavenge dead vegetable matter. Over 7,000 species of harvestmen have been indentified, and many more are expected to be identified in time. Harvestmen are neglected, taxonomically, because they do not impact man directly, at least not in serious ways. As one writer put it, they exhibit good habits (by not causing us harm). As a result, though common throughout their range, they are not on man's radar screens. In Texas, 18 species have been identified. Only one of their 37 families worldwide (the Phalangiidae) contains the species we call daddy long legs.
The body of a harvestman is not divided into a separate head, abdomen, or thorax. Instead, one undivided body part provides all the organs that, for more complicated animals, several body parts are required to handle. The harvestman's two eyes are positioned on the dorsal surface of the anterior third of the body, in a slight protuberance that positions the eyes so that they look sideways.
Masses of daddy long legs may congregate together at certain times of the year, possibly in connection with mating. When threatened, the mass of harvestmen sometimes rises and falls in huge waves, creating a visual effect that easily frightens anyone unfamiliar with these otherwise innocuous creatures. It does not help the harvestman's reputation that a thoroughly incorrect urban legend has circulated for years that they are the most venomous arachnids on earth. That legend has it that, despite their hardy venom, they are harmless because their teeth cannot bite humans. In fact, they have no venom glands at all. The worst that they can do is taint the air with a sickly-sweet-noxious odor from their musk glands. Many thanks to Nancy T. for these photos.... ---------------------------------------------- Harvestmen are harmless, without venom glands or mouthparts capable of biting humans. We are investigating the risk of secondary infections that may occur as a result of bites from other, otherwise harmless arachnids whose venom is known to pose little or no danger to humans. In the process, we are collecting information on experiences persons have had with such bites. Please contact us about your personal experiences, if you have been bitten by any spider, including jumping spiders and garden spiders (the bites of which typically produce a transitory inflammation, but resolve within a few days without medical attention), whether recently or in the past thirty years, anywhere in the world. For example, the bite of a species of garden spider, the golden orb spider of Australia [Nephila edulis] typically is unremarkable, but on occasion produces medically significant secondary infections; the frequency and nature of bites experienced from that species of spider is also a part of this study. The object of this study is to collect data that might relate to a mysterious series of spider-related infections, involving a special pathogen, that took place in the United States and in Australia between 1977 and 2006. Although only fifteen such infections were reported to medical establishments, seven appear to be associated with spider bites. Some authorities suggest that the number of actual infections of this type that occurred in the U.S. and Australia during the past thirty years is much larger, but that they have been underreported. Underreporting of specific kinds of infections can occur, either because the persons infected chose not to seek medical assistance, or the medical establishments misdiagnosed the infections as being caused by other infectious agents. We are seeking to establish an estimate of the number of human spider bites that occur each year by these and similar spiders, whether the bite resulted in injury to the human or not. Next, we hope to establish the number of instances where the bite (1) became inflamed and/or infected, then resolved without medical intervention, or (2) infected, ulcerated, or led to a generalized sickness, and required medical intervention. ---------------------------------------------- Back to: Texas Spiders Back to: Bugsinthenews |
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