BEHAVIOUR 193 



Strong, and the animals definitely rely on them. Thus, in Marineland, when 

 Pilot Whales were first introduced in force, they stayed close together and 

 even slept and awoke together, and Bottlenose Dolphins, once they had 

 become used to their new environment, swam about separately, to join 

 forces the moment anything frightened them. The Pilot Whale of Marine- 

 land (California) became aggressive when he was alone in the basin for 

 a fairly long time. When dolphins were introduced, he became friendly 

 again. All this bears out a statement by Uda and Nasu (1956) that, in 

 the Pacific, schools of whales show a perceptible increase in number after 

 hurricanes. The schools probably keep together by making sounds to one 

 another, a method of communication which has been positively established 

 in the case of Black Sea Common Dolphins. Once a school of big whales 

 has become dispersed by hunters, it apparently finds its way back by 

 sounds as well. W'hales, like apes, probably produce continuovis noises, a 

 subject which we shall investigate more fully in the next two chapters. 



Hvmting packs, of the kind found in wolves, are known among Killer 

 Whales, and there have been seen attacking dolphins, seals, sea-lions, 

 and even walruses. The Killer Whales first surround their victims, herding 

 them together and cutting off all means of escape. The older dolphins 

 generally form a protective circle round their young, and the Killer 

 Whales, singling out one of the weaker parents, pounce on him. As 

 happens in so many herds, weaker members are often pushed into the 

 most vulnerable spots by their fellows. Occasionally, one or more Killer 

 Whales split their victims' ranks to carry off one of the young. They are, 

 however, careful to avoid old walruses, for which they have a healthy 

 respect. Caldwell states that schools of dolphins of the species Stenella 

 plagiodon make organized attacks both on shoals offish and on big cuttle- 

 fish, though he does not report their method of attack. 



The strong ties between members of a particular school often take the 

 form of mutual aid and, particularly, of assistance to wounded animals, 

 to an extent rarely found among terrestrial mammals, which generally 

 leave the weak and sick to their own devices, or actually set upon them. Of 

 terrestrial animals, only elephants have been reported to come to the aid 

 of their wounded. When this happens, two friends hold up their comrade 

 on either side with their bodies and tusks. 



The best description of mutual aid between Cetaceans comes from two 

 members of the stafTof The Living Sea Gulfarium at Fort Walton Beach in 

 Florida. They noticed that a submarine dynamite explosion had injured 

 a Bottlenose Dolphin in the bay. The animal sank, but immediately two 

 others came to its assistance and, pushing their heads under its flippers, 

 carried it up to the surface for air (Fig. 104). Being unable to blow them- 

 selves while thus occupied, they would let go of their wounded comrade 



