226 THE LIVING ANIMALS OF THE WORLD 
and ventral, a movement which causes very slight disturbance of the water. The appearance 
of the dory in these actions is suggestive of suppressed excitement, his eyes being fixed on 
his prey. I do not recollect seeing him actually swallow another fish, but have no doubt that 
he gets near enough to a sprat, for example, without alarming it, to seize it by the sudden 
elongation of his curious jaws.” The way in which these jaws are elongated is admirably 
shown in the photograph on page 622. 
Passing now to the Mackerel Family, we arrive at a group of considerable importance 
from an economic point of view. Extremely active, migrating, and predaceous, mackerel swim 
in shoals and seize their prey with great voracity, hunting merely by sight, and snapping at 
anything moving through the water, especially if it is silvery, like a small surface-fish. The 
various species differ greatly in size, ranging from the Common Mackerel of about 18 inches 
long to the giant Tunny weighing nearly half a ton. 
COMMON MACKEREL swim in vast shoals, or “ schools,” as they are called, and one half a mile 
wide and at least twenty miles long is on record. Mackerel feed on the young of other fish 
and small fish generally, and, when these are not to be had, on minute crabs and shrimps. 
They are very prolific, a 
single mackerel laying 
from 430,000 to 540,000 
eggs, 
The TUNNIES are 
amongst the largest of 
the surface-fishes of the 
ocean. Abundant in the 
Mediterranean Sea, they 
occur occasionally in 
British waters. For 
centuries the flesh of the 
tunny has been held in 
high regard as food, and 
it is frequently seen in 
the Lisbon markets at 
the present day. The 
4 flesh, which is as red as 
F 1 
Photo ty Reinhold Thiele & Co.] huneery. Lanes IC; beef, is cut up and sold 
JOHN DORY by weight. The Boniro 
In the centre of each stde ts a round black spot surrounded by a pale yellow ring closel y resembles the 
tunny, but is a much 
smaller fish, which preys largely upon flying-fishes, which it follows for long distances. 
Peculiarly interesting are the SUCKING-FISHES. The name by which they are commonly 
known is bestowed on account of the presence of a large oval sucker, placed on the top of 
the head and extending backwards over the shoulders —an organ formed by modification of 
the back-fin. By means of this sucking-disk these fishes are enabled to attach themselves to 
sharks, turtles, ships, or any large object floating in the sea. The hold which they obtain 
is so strong that it is almost impossible to remove them by force. Being poor swimmers, 
this method of transportation enables them to pass rapidly to fresh feeding-grounds. 
The natives of Zanzibar, Cuba, and Torres Straits are said to employ sucking-fishes in 
the capture of sleeping turtles, the fish being secured by a ring round the tail, and liberated 
as soon as a sufficiently near approach to the quarry has been made. About ten different 
species are known, the bulkiest of which attains a length of 2 feet and a weight of about 
8 lbs., a longer but more slender species measuring 3 feet. 
Carnivorous, of small size, and feeble swimming-powers, the family of the WEAVERS are 
remarkable rather for their disagreeable qualities than anything else, though at least one 
