Order CETACEA— WHALES, DOLPHINS, AND 
PORPOISES 
Though externally the form of the various species of Whales and 
Dolphins is fashioned in the likeness of a fish, when we come to examine 
their internal structure and habits, we find this resemblance is only super- 
ficial, and that they are really warm-blooded animals, wonderfully adapted 
to an aquatic existence, bringing forth and suckling their young like 
other mammals, and requiring to draw their breath from the atmosphere 
by rising to the surface at frequent intervals. 
To facilitate this movement, the tail is made to act as a powerful 
propeller, and is characterised by having the flukes or blades arranged 
horizontally and not in an upright position, as in the tail of a fish. 
The well-known spout of a whale is merely the exhausted air driven 
from the lungs, and being warm and moist has the appearance of a 
fountain of fine spray as it meets the outer and colder atmosphere, when 
respiration takes place ; but should the animal blow just before reaching 
the surface, water is driven upwards as well. About half an hour is said 
to be the length of time a whale can remain under water, though they 
usually come to the surface at much shorter intervals. The longest stay 
of a Greenland Whale observed by Scoresby was fifty-six minutes. 
The fore limbs or flippers are outwardly formed like paddles, and 
only capable of movement at the shoulder joint, but hidden within their 
structure they have an arrangement of bones and muscles not unlike those 
of the human hand and arm ; while the hind legs, represented only by 
55 
