98 
Psyche 
[March-June 
rather than gamble on a larger web trapping more food. Early food 
deprivation experiments (Witt, 1963) show that the spider con- 
tinues to build the same size web when deprived of food, but with 
less thread until finally a decreasing in web size occurs. Because 
our hungry (light-fed) animals were kept on a diet closer to a main- 
tenance level than a deprivation level, we observed no decreases in 
web dimensions. 
Feeding conditions in a natural environment vary more than those 
imposed in a controlled laboratory. Yet the spider is able to survive 
in these naturally diverse conditions because of its adaptability. In 
situations where there is little food available, the spider is able to 
survive by growing at a slow rate and maintaining the same size 
web. Where food is abundant, the spider takes advantage of the 
situation, growing at a fast rate and increasing the size of its web. 
The spider has developed a method for coping with a wide range 
of feeding conditions. By varying its body and web growth, the 
spider can survive under the diverse conditions imposed by nature, 
thus minimizing the necessity of seeking new food supplies and re- 
locating the web. Our findings provide new insight into the spider 
as an example of an animal that adapts itself successfully to its en- 
vironment. 
Summary 
Spiders from two cocoons of Araneus diadematus were exposed to 
five weeks of two different feeding schedules: one group was of- 
fered large amounts (one housefly per day) of food, the other group 
scarce (one fly every ten days) amounts. Although both groups in- 
creased in weight, weight gains of the heavy-fed group were signifi- 
cantly greater than those of the light-fed group, regardless of cocoon 
origin. Within each group there was a wide variation in the growth 
of individual animals, indicating the presence of factors other than 
food supply; i.e. animals with extreme weights within a group at 
the onset remained the extremes. 
In conjunction with increases in weight, over the three week period 
of observation, webs of the heavy-fed spiders showed an increase in 
size but not in regularity and shape in comparison to webs of the 
smaller, light-fed animals of the same age which did not change. 
Such data suggest an increased chance of survival of the species 
through variations in rate of growth and maturation dependent on 
environmental factors. 
