CHAPTER III 



EFFECTS ON THE HIGHER INVERTEBRATES 



The striking effects of inanition on the invertebrates are very illuminating 

 in comparison with the more complicated phenomena met in starvation and in 

 the various deficiency disorders of the higher vertebrates, including man. It is 

 difficult to summarize satisfactorily the effects of inanition upon the large and 

 varied group of organisms included under the metazoan invertebrates. Never- 

 theless it will be profitable to review briefly some of the outstanding results as 

 to duration of inanition, effects on weight, size and form of the body, changes 

 in various organs and tissues, effects on the gonads and sex, effects on cell 

 structure, effects on development, regeneration during inanition, and recovery 

 upon refeeding. The data for the various groups of invertebrates will then be 

 given in detail. 



Summary of Effects on the Higher Invertebrates 



Duration of Inanition. — The period of endurance naturally varies not only 

 with the species, age, and individual, but also with the type of inanition, tem- 

 perature and other external conditions. Hibernation or similar dormant peri- 

 ods are not comparable with ordinary inanition, because in the former case 

 special stores of food are accumulated in the body for this purpose, and also 

 because the metabolism is decreased so as to lessen greatly the need for nutri- 

 ment. Some of the longer periods (years) of starvation reported for the leech, 

 snail, spider and various insects are probably to be accounted for by unusually 

 extensive periods of dormancy. 



For complete starvation (total inanition) of adults, the periods reported for 

 different species range from one or two days up to several years. In the Coelen- 

 terata, the period ranges from six weeks or less in the jellyfish Cassiopea to four 

 months for Hydra; but newly hatched Hydra may survive only four or five days. 

 The Platyhelminthes (fiatworms) may endure six to fourteen months. The 

 parasitic roundworm Ascaris can endure only seven to ten days, whereas the 

 blood-leech Hirudo after engorgement may last one to three years. Among 

 Echinoderms, the adult starfish can endure for months, while the larvae usually 

 perish within a few weeks (maximum 60-70 days). Of the Mollusca, the mussel 

 Mya endures only 18 days, the snail Helix four months (or in some cases possibly 

 for years). Of the Arthropoda, the waterflea Daphnia endures only n days, 

 the crayfish Astacics and spider Epeira a few months, the crab Cancer and 

 the scorpion 18 months. The insects show enormous variation in different 

 species, varying from only one or two days in the flies, bees and ants, dragon-flies, 

 etc. to possibly several years for the bedbug. Among the beetles (Coleoptera) 

 alone, the endurance in different species varies from two days to over six years. 



26 



