LOCOMOTION AND LOCOMOTORY ORGANS II3 



Two different observers recorded that Common Dolphins, swimming at 

 some distance from their ship and hence unhkely to have benefited from 

 the bow waves, kept up 20 knots for a considerable period of time. 

 Speeds of 30-32 knots were measured in dolphins swimming in the bow 

 waves of a destroyer. Captain Mörzer Bruins reported that dolphins had 

 no difficulty in keeping up with the Tarakan whose speed was 14-5 knots. 

 Dolphins of the genera Steno and Prodelphitius, however, fell behind the 

 Tarakan, though they could keep up with the slower Enggano which was 

 making 1 1 -5 knots. River dolphins swim much more slowly, and Layne 

 measured a normal speed of 2 and a maximum speed of 10 knots in the 

 Boutu. Six knots appears to be the top speed oï Sotalia plumbea, a marine 

 species of Dolphin from the Malabar coast of India, and Vladykov 

 measured a maximum speed of 10 and a normal speed of 6 knots in the 

 Beluga. In the case of False Killers, Captain Mörzer Bruins measured 

 14-5 knots, and he also established that a Bottlenose Dolphin from the 

 Red Sea ( Tursiops aduncus) could swim faster than a ship making i 7 knots. 

 This is in agreement with the figures for the ordinary Bottlenose Dolphin 

 [Tursiops truncatus) which is said to elude all boats making less than 22 

 knots. Comparing these speeds with those of ships, we find that the faster 

 whales and many dolphins can keep up with modern liners. Still, the 

 comparison is a little unfair, since ships are not submerged and have to 

 overcome niuch less resistance. A submarine would, therefore, provide a 

 much better analogy, and using it we find that many Cetaceans are far 

 superior, for submarines only make 6 knots when submerged and 15 knots 

 on the surface. 



On the whole, it is true to say that the larger a ship the faster it is. In 

 fish speed appears also to be directly proportional to size. Now this 

 does not hold for Cetaceans, since an 8-foot dolphin can easily keep up 

 with a 70-foot Fin Whale which weighs almost 1,000 times as much. 

 True, speed boats of less than 100 tons can also keep up with 1,500-ton 

 destroyers, but, once again, there is really no comparison, for the destroyer 

 has to cut through the water, while the speedboat skims the surface. The 

 fact, then, that two similarly built animals of such tremendous diflference 

 in size can yet reach the same speed, is unique, so much so that not only 

 biologists but all sorts of marine engineers are very interested in this 

 phenomenon. It is therefore not surprising that the Admiralty Experi- 

 mental Station in Haslar (England) feels that scientists have much to 

 learn from Cetaceans, and that the British Association for the Advance- 

 ment of Science, during their annual meeting in Newcastle in 1949, 

 devoted an entire joint session of the zoological and technical sections to 

 the study of this problem, with Prof. Burrill presenting the technical, 

 and Dr Richardson and Pi'of Gray the biological aspects. Though their 



