CHAPTER IX 

 THE FOOD OF ANIMALS— CARNIVOROUS INSECTS 



The huge phylum of Arthropoda embraces an extraordinary 

 -variety of forms adapted to life under the most diverse conditions, 

 and frequently of carnivorous habit. The most characteristic 

 feature in all these animals is the possession of paired, jointed 

 limbs, specialized for the performance of various functions. Some 

 are used in locomotion, others serve as vi^eapons of offence and 

 defence, and others again act as jaws. The nervous system and 

 sense organs are exceedingly well developed, and this is asso- 

 ciated with extreme activity and, in certain cases, with intelligence 

 •of a high order. 



Arthropods are divided into two great groups — one of Air- 

 breathers (Tracheata), including Insects, Scorpions (and their 

 allies). Centipedes and Millipedes, and the primitive form Peri- 

 patus; the other of aquatic Gill-bearing forms (Branchiata), 

 ■embracing Crustacea and their allies. It will be convenient to 

 begin with Insects and finish with Crustacea. 



INSECTS (Insecta) 



Insects include the large majority of land animals, and of all 

 terrestrial invertebrate groups have been most successful in the 

 struggle for existence. This no doubt results jrom their great 

 activity, which in its turn is dependent upon very perfect arrange- 

 ments for purifying the blood and introducing fresh oxygen into 

 the system. Nor must it be forgotten that most members of the 

 <:lass are endowed with the power of flight, which is in itself a 

 great advantage, especially in the search for suitable food. The 

 possession of this power largely accounts for the wide distribution 

 ■of the group. A simple and typical insect, the Cockroach, has 

 been described at some length in vol. i, p. 343, and it is not 

 necessary to repeat much of what was there said, though a few 

 ■of the more salient points may with advantage be reviewed. The 

 body of an insect is clearly divided into three distinct regions: 



