nd of moderate size, about 12
ft. long. They both feed on cuttle-fish and minute shrimps, but the
Beluga has many teeth and the narwhal (with the exception of some
rudimentary ones) only a single pair, and these in the front of the
upper jaw. In the female narwhal their pair of teeth remain
permanently concealed in the jaw bone, and so does the right side one
of the male. But the left side tooth of the male grows to an enormous
size, projecting horizontally in front of the narwhal to a length of
seven or eight feet. It is a powerful weapon, and is formed of ivory
spirally grooved on the surface. The narwhal was called "the unicorn
fish" or "Monoceras" in ancient times, and its spirally marked tooth
was confused with the horn of the terrestrial unicorn--the rhinoceros.
Very rarely the right tooth of the male narwhal grows to full size
side by side with the left tooth. 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 (probably 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