386 MORE ABOUT WHALES 



A specimen showing this double-toothed condition is in 

 the Natural History Museum. A most curious fact, quite 

 unexplained as yet, is that the spiral grooving on both the 

 teeth turns in the same direction ; in both it is like a 

 spiral staircase in mounting which (starting from the base 

 implanted in the jaw) you continually turn to the right. 

 Now, in all other animal structures which have a spiral 

 growth and are paired one belonging to the right side 

 of the animal, the other to the left, as, for instance, the 

 spirally marked horns of antelopes and the more loosely 

 coiled horns of sheep and cattle one of the pair forms a 

 right-handed and the other a left-handed spiral. They 

 are " complementary " ; one is the reflection, as in a mirror, 

 of the other. Why the narwhal's tooth does not conform 

 to this rule is a mystery. 



It is a remarkable fact that only a few whales and 

 porpoises eat fish or the flesh of other whales. The large 

 toothed-whales, including the cachalot or sperm whale, and 

 also the Ziphius-like beaked whales, live upon cuttle-fish. 

 And it seems that they know where to hunt for this 

 special article of diet and how to find it in quantity (pro- 

 bably at great depths in the ocean), which naturalists do 

 not. Many new kinds of cuttle-fish have been discovered 

 by examining the contents of the stomach of captured 

 whales. The sperm whale feeds on monster squid and 

 poulp such as we rarely, if ever, see alive or washed up on 

 the shore. The hide of these cuttle-fish-eating whales 

 and porpoises is scratched and scarred by the hooks 

 attached to the suckers on the arms of the great cuttle- 

 fish, and a test of the genuine character of ambergris 

 which forms as a concretion in the intestine of the sperm- 

 whale is that it contains fragments of the horny beaks and 

 hooks of the cuttle-fish digested by the whale. The food 

 of the whalebone whales consists of minute Crustacea and 

 of the little floating molluscs known as Clio borealis, as 



