Defensive Mimicry in Phalangidae

Psyche: A Journal of Entomology, Sep 2018

George Dimmock

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Defensive Mimicry in Phalangidae

International Journal of DEFENSIVE MIMICRY IN P[-IALANG_[DAE. BY G.EORGE DIMMOCK CAMBRIDGE MASS. WHILE in Switzerland, in September 1880, I noticed a peculiar kind of defensive mimicry on tile part of an undetermined species of ph(langidae, which I have nowhere seen recorded. In approaching a rocky ledge on the road between St. Gingolph and Novel, near the south side of Lake Geneva, my attention was attracted by what I at first supposed to be a large number of small webs with large spiders in them, but which I found, on nearing the ledge, to be a great num1)er of phctlangidae, or 'harvest-men." On coming near the place where they were, each of them began a rather rapid dorso-ventral motion of the body, swinging it backward and fbrward on their legs.. As the rock on which they rested was nearly perpendicular, and their eight outspread, long, and slender legs rested on the projections of the irregular rocky s(rface, allowing their bodies to swing in the cavities between these projections, each of them resembled very closely, viewed from a short distance, a smM1 geometric web containing a spider, for, as I have oien observed, some species of spiders, when disturbed, swing their web rapidly back and tbrth, while cling, ing at its centre. The motion of the body, in the species of pbalangidae that I observed, was of an impulsive, jerking nature, like the motion of the spiders just mentioned, when similarly disturbed. At each sudden movement of my hand a large part of the phalangid(e, with which the rock was dotted to the nmnbet of thousands, would recommence the motion described above, but none of them ran away until they were touched, seeming to trust in the efficacy of their mode of imitative defense. Can it be that the spiders which cause the before-mentioned swinging of their web when disturbed are more ill-tasting than.phalangidae themselves,* nd that the phalangidae, by imitation, avoid being eaten by birds? Or is it, on the contrary, tile spiders which, for their own protection, imitate the phalangidae ? That the motion described above originated with the spider and later served the phctlagidae fbr protection seems to me more probable, ibr the spider has, to all .appearances, another and a more natural purpose in shaking his web. As a sailor on deck shakes and yanks his ropes to see if they are firmly fastened and fi'ee fi'om encumbrances, so the spider shakes his web from his central resting place to determine if each fastening is in proper order, or if an insect has tangled itself in any part of hisweb. The phalangidae would easily deceive birds by this motion, which, otherwise, for them, seems to have no explainable purpose. Although I had often seen single speclinens of phalangidae goihg though the same motions on horizontal surfaces, even while they were walking, it was left to this great multitude of specimens, hanging on a jagged ledge, to snggest, by actually deceiving me at first sight, the probable object of this strange tootion.. Paris, Frazce, 3 Dec. 38. - Many species of phalan’/dae pour out secretion vsmheelnlanaddnlsdbtiurtadrssbteedd,o twnohotiucsah;lwibasuytss,ufafgircteiaeesn,tteltsyhiasdnissdeacgdrrieestetiaaobsnltee,msaiiynn not be protection from the attacks of certain birds. International Journal of Peptides Advance s in ht p:/ w w.hindawi.com Virol og y Hindawi Publishing Corporation Hindawi Publishing Corporation ht p:/ www.hindawi.com Submit your manuscr ipts http://www.hindawi.com Research International Stem Cells International Hindawi Publishing Corporation ht p:/ www.hindawi.com Zoology International Journal of Journal of Signal Hindawi Publishing Corporation ht p:/ www.hindawi.com Transduction Research International Hindawi Publishing Corporation ht p:/ www.hindawi.com Anatomy Research International Research International Advances in Hindawi Publishing Corporation ht p:/ www.hindawi.com Hindawi Publishing Corporation ht p:/ www.hindawi.com Enzyme Research Journal of Genomics Journal of Nucleic Acids The Scientiifc World Journal


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George Dimmock. Defensive Mimicry in Phalangidae, Psyche: A Journal of Entomology, DOI: 10.1155/1882/70834