1902 Encyclopedia > Arachnida > Arachnida - Order V: Scorpionidea - Sub-Order II: Scorpiones - General Observations

Arachnida
(Part 19)



(19) ARACHNIDA - ORDER V: SCORPIONIDEA - SUB-ORDER II: SCORPIONES - GENERAL OBSERVATIONS

GENERAL OBSERVATIONS. - The sub-order Scorpiones forms a remarkably homogeneous group. It has been divided, however, into several families by Koch (Die Arachn.); and various genera, based principally on the number and distribution of the eyes, the form of the fore margin of the cephalo-thorax, and the structure of the comb-like appendages attached to the under side of the abdomen, have been characterized. The species are tolerably numerous, but the whole group greatly needs revision, both in respect to its family and generic divisions, as well as in regard to the identification and determination of the species. Those found in Europe are of comparatively small dimensions, and are confined to the southern parts of the Continent; the majority are tropical, attaining their greatest size- nine or ten inches in length - in central Africa and South America. They are nocturnal in their habits, living by day underneath stones, behind the loose bark of trees, among the ruins and debris of old walls and buildings, and preying upon insects and other Arachinida; they are said to be very partial to the eggs of spiders and insects. It does not appear that they are able to inflict any great injury with the, often formidable looking, crab-like claw with which their palpi terminate, though they can gripe and hold on firmly with them. the would inflicted by the sting at the end of the tail is certainly more or less venomous; the amount of venom is probably dependent on the age of the scorpion, and the season of the year; and the effect of the sting is no doubt dependent upon the state of health, constitution, or predisposition of the person injured. Experiments, tried by Maupertuis, upon poultry and dogs stung by exasperated scorpions, resulted in their almost entire immunity from bad effects, while in Redi's experiments, the sting proved fatal in some instances to pigeons. These experiments were tried with European species of scorpion, which would probably be less venomous than those living in tropical countries. For a recent memoir on the poison of the scorpion, and the mode in which it acts, see Dr. Jousset, Ann. Ent. Soc. France, 1872, p. 151; also Comptes Rendus, 1870, pp. 407-411. According to Jousset, the venom acts directly upon the red globules of blood, paralyzing them, so that becoming agglutinated together, they obstruct the entrance to the capillaries and stop circulation. The peasant inhabitants of Tuscany are said to handle scoripions without fear; but this may be chiefly from a skilful mode of handling them. A scorpion does not appear to be able to move its tail or its sting in a lateral direction, nor does it strike downwards. The present writer has seen natives of Egypt handling large, and it is believed very deadly ones with impunity, but then they always held them tightly by the last joint of the tail. It was a common practice so to catch these creatures, and after breaking off the tip of the sting, to let then loose again; but this infliction generally appeared to produce a kind of paralysis of the whole tail, and probably the poor animal would soon die.





Though the well-known tale of the scorpion, when surrounded by fire, stinging itself to death, has been perpetually repeated, and has even been related to the present writer with some very minute and extraordinary details, it must be held to be merely a "traveller's story." cross-examination, in the special instance noted, very much nettled the narrator at the incredulity which led to it, but it threw more than a doubt over the conclusiveness of the experiment narrated. Probably in some instances the poor scorpion has been burnt to death; and the well-known habit of these creatures, to raise the tail over the back and recurve it so that the extremity touches the fore part of the cephalo-thorax, has led to the idea that it was stinging itself. Perhaps, under the pain of scorching, there may have been convulsive efforts and movements of the highly nervous and sensitive tail in this position, and the point of the sting may even have been inserted between the articulation of the cephalo-thorax and abdomen; and what more would be wanting to make a wonder-loving traveler believe that it had really committed suicide? The progress of scorpions is neither rapid nor graceful; they are unable to run without elevating the tail to an erect position, which seems to be necessary to enable them to preserve their balance.

CLASSIFICATION OF THE SCORPIONS. - The following is Koch's systematic division of the scorpions.

Order SCORPIONS

Fam. I. With six eyes, Scorpionides. - One genus only, Scorpius (Ehrb.)

Fam. II. Eight eyes, Buthides. - Five genera: Buthus (Leach); Opistophthalmus (Koch); Brothers (ld.); Telegonus (ld.); and Ischnurus (ld.)

Fam. III. ten eyes, Centrurides. - Two genera : Centrutus (Ehrb.); and Vaejovis (Koch).

Fam. IV. Twelve eyes, Androctonides. - Three genera: Androctonus (Ehrb.) ; Tithyus (Koch); and Lychas (ld.)

One hundred and twenty-two species, distributed various among the above eleven genera, have been described by Koch (Die Arachn.); but many others also have been added to these, in isolated papers by other authors. For another systematic arrangement, as well as on the group generally, with descriptions of seventy-eight species, see Walckenaer, Ins. Apt., iii. pp. 14-75, where other works are also referred to. Scorpions have been found in a fossil state, as well as in amber, in which substance a species of Tithyus (T. eogenus) has been described by Menge.





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