350 ^^^ ANIMAL KINGDOM 



nHive 



Hioh ridge. 



Figure 17.23. The contour lines indicate a high ridge separating the hive from a 

 syrup source. Bees returned to the hive along the dotted line, and in their wagging dance 

 indicated the true direction (heavy arrows), but 149 meters distance. (After von Frisch.) 



combs, Upward is substituted for sunward (Fig. 17.21). Thus, if the 

 source lies toward and a little to the right of the sun, the straight rush 

 is a little to the right of straight up. Von Frisch found that most 

 "listening" bees learned the direction of the source within a few de- 

 grees of its true position. 



The most spectacular of all experiments by von Frisch involved 

 placing the hive and sugar source on opposite sides of a towering rock 

 ridge (Fig. 17.23). Bees discovering the source filled up and flew around 

 the end of the ridge to get home, more than twice the distance straight 

 through the ridge. Once there, they communicated to others the flight 

 distance, but signalled the true direction! Excited bees then flew out 

 of the hive straight at the cliff. Meeting this obstacle they turned and 

 went around the end, flew back along the outer side to the proper point, 

 and then circled to locate the source. It is evident, therefore, that the 

 bee language can be adapted to specific problems. 



In another experiment von Frisch placed the hive at the base of a 

 radio tower, and the source on top of it. Bees taken to the top filled up, 

 went home, and round-danced. Many others went out searching, but 

 none of them went high enough to find the honey. When the hive was 

 placed some distance away from the tower, the returning bees wag- 

 danced. Others flew out in the right direction, for the right distance, 

 and were seen circling around the base of the tower, but none of them 

 found the source at the top. Bees, apparently, have no word for "up." 



Von Frisch's discoveries have greatly broadened the field of animal 

 behavior. If bees can "talk," what can other invertebrates do? 



Questions 



1. How does an arthropod escape from its old exoskeleton? 



2. What are gastroliths? 



3. Describe the role of the sinus glands in the crustacean endocrine system. 



4. Define neurosecretion. 



5. How was the role of the corpora allata in insects detennined? 



