PREY CAPTURE IN MANTIDS* 



HORST MiTTELSTAEDT 



Wilhelmshaven 



The problem of absolute optic localization is one of the earliest discussed 

 in human psychophysiolog>% and one which was disregarded for the longest 

 time in the physiology of the invertebrates. The neglect may be merely due 

 to the fact that there are only a few cases in the invertebrates where that 

 special question can be asked, one of these being the case of the praying 

 mantid. 



But let me explain the problem in the human case first. If you are to pick 

 up, say, a pencil lying in front of you on a table and if you have time enough 

 to do that without a rush, you not only see the pencil but your hand too. 

 Therefore, you merely have to move your hand in such a way that the 

 difference in position of these two observed things will disappear. The 

 situation will change fundamentally if you are not allowed to see your hand 

 or if movement goes too fast, as, for instance, in playing tennis, hammering 

 nails, or throwing a ball into a goal. In such a case it normally will not be 

 possible to correct the movement once started by watching the difference 

 between its direction and that of the goal. Consequently success here de- 

 pends upon information about the direction of the goal only. We certainly 

 may assume our optic centers to be able to transmit a signal pattern rep- 

 resenting the directional component of the retinal image concerned. Thus 

 these centers can be expected to provide information about the direction 

 of the goal relative to the eyeball. But, of course, that does not necessarily 

 mean information about the direction of the goal relative to the body. For 

 we can move our eyes and our head. It's fairly clear what should be con- 

 cluded : the message steering the movement of the hand should contain 

 information about the position of the eyeball and of the head too. How this 

 information is gained in fact is the question — discussed in human psy- 

 chology since the times of Helmholtz (1866) — with which I shall deal in 

 the related case of the mantid. 



Mantids, h'ing in ambush all day, detect their prey by means of their 

 well-developed compound eyes. The prey is faced by movements of the 

 head, the eyes being firmly attached as in all insects. If the prey is the 

 proper distance away, it is captured by a sudden stroke of the forelegs. Two 



* This investigation has been carried out at the Max-Planck-Institut fiir Verhaltens- 

 physiologie in Wilhelmshaven. The author is greatly indebted to Dr. R. Wette for 

 his advice about statistics, to Frau L. Dinnendahl for the preparation of the figures, 

 and to Dr. T. H. Bullock and Dr. B. T. Scheer for carefully reading the manuscript. 



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