BLUE SHARK. 
1131 
N. Mag. Naturv., Bd 29 (1884), p. 116; Doderl , Man. 
Ittiol. Medit., fasc. II, p. 42; Lill.j., £v Norg. Fna, 
Fisk, vol. Ill, p. 609. 
Iii Plate L, tig. 3 we give a representation of a 
young Blue Shark, 41 cm. long, from the Indian Ocean. 
It was cut out of the belly of the mother-fish. The 
specimen is sufficiently developed and well preserved 
enough to give a better idea than a stuffed example 
of the appearance of the species. The Blue Shark, 
however, attains a considerable size, in ordinary in- 
stances a length of 2 to 3 or 4 m.°, and the form 
varies during growth. The pectoral fins become con- 
siderably longer and narrower, their length being some- 
times thrice their breadth. The relative size of the 
eyes diminishes from about '/? to Vio °f the length of 
the head. The form of the jaw-teeth (fig. 326) is 
altered as shown in the figure; and the number of 
specimen 3 1 , / 2 m. long was taken in Travemtinde Bay 
and described by Walbaum 6 . During the previous 
year a specimen is said to have been caught off Kielb 
According to Cough the Blue Shark roves round the 
English coast during summer, but leaves those waters 
at the approach of winter. 
Though the Blue Shark attracts most attention as 
it swims at the surface, it also descends to a consider- 
able depth (at least about 100 m.), and here is perhaps 
its most congenial home. Light is apparently obnoxious 
to it, for at the surface and in the upper strata of the 
water, so long as the light is powerful, and when it is 
desirous of fixing a steady gaze on some object, it keeps 
drawing the nictitating membrane up and down over 
its eyes. In the Mediterranean the young make their 
appearance during May and June (Doderlein). Oppian 
celebrated in verse/ the care devoted by the parents 
A 
Fig. 326. Jaw-teeth of the right side in a young (M) and an adult- ( B ) Blue Shark. J / 2 nat. size. After Muller and Henle. 
their transyerse rows, one behind the other in each 
jaw, increases from 2 to 5. 
In the tropical seas the Blue Shark is dispersed all 
round the globe. In Europe it is common in the Medi- 
terranean and at least not rare on the south coasts of 
England and Ireland. Even in St. Andrews Bay (Scot- 
land), according to McIntosh, it is not uncommon, 
and according to Couch it strays up to the Orkney Is- 
lands; but further to the north and east it is appa- 
rently but an occasional visitor. In November, 1883, 
Collett received a specimen 16 dm. long that had 
been taken at the very head of Christiania Fjord, and 
Blue Sharks have been caught in the westernmost parts 
of the Baltic. At the beginning of October, 1753, a 
to their offspring. When any danger threatens, the 
mother (or, according to others, the father) opens its 
mouth for the young to take shelter in its pharynx 6 or 
even in its stomach. The fry are, however, soon ca- 
pable of defending and feeding themselves, for they 
come into the world fully developed for leading an 
independent existence, and measuring, according to a 
note of van BenedknV, at least 60 cm. 
The diet of the Blue Shark consists principally of 
fish of all kinds. In the stomach of a specimen 6 ft. 
long Couch found a large Picked Dog-fish and a Con- 
ger, both bitten right in two, and a Gurnard. In an- 
other he found four Mackerel, half a Garpike, and so 
many Herrings, quite whole, that the fisherman sold 
a Lilljeborg states as much as 7 1 /, m. 
b Cf. Bloch, 1. c. 
c Cf. MSbius and Heincke, 1. c. 
d Halieuticorum lib. 1. From the beginning of the third century, A. D. 
e Cf. the method employed by the Chromidce of preserving their eggs and fry in the branchial cavity. Agassiz, A Journey in 
Brazil , p. 222. 
f Poiss. Cotes Bely ., p. 4; Mem. Acad. Roy. Belg., tom. XXXVIII (1871). 
