„5 DISCOVERY REPORTS 



physalus). Part I, as far as permitted by the nature of the observations, is an account of the whales 

 as they have been seen at the surface. Inferences of what goes on below the surface, and comparisons 

 with the observations of earlier authors, are left as far as possible until Parts II and III. 



I. APPEARANCE AT THE SURFACE 



Opportunities of observing cetacea occur both when they are under water near the surface and when 

 they break surface to blow.^ They have also been known to break surface without blowing. As, 

 however, they are usually blowing when they are seen, it will be convenient first to consider various 

 ways in which they come up to breathe. 



Breaking surface to breathe 



The length of time a mature Fin whale shows above water usually varies from 3 to 6 sec. and some- 

 times lasts for as long as 7I sec. ; calves show for shorter periods of 2-2^ sec. The time is divisible into 

 two periods : the first a very short period of little more than i sec. during which the head emerges and 

 submerges again, and then a period of variable duration, of from 2 to 6| sec. during which the rest of 

 the body follows. The first period seems to vary comparatively little. The length of time the whale 

 shows above water depends then mainly upon the length of the second period, and this depends very 

 largely on what he is doing. 



For simplicity of treatment three examples may be chosen to illustrate the different methods employed 

 in breaking surface. They are discussed in later pages but it may be well here to bear in mind that no 

 one of the methods need be rigidly adhered to. 



(i) Slow. A whale breaking surface to blow very leisurely, approaches the surface horizontally and 

 swims slowly (Fig. la). Its upward motion, in a more or less horizontal position, resembles the action 

 of a submarine and can be watched for several seconds before it breaks the surface. The head and back 

 break surface almost simultaneously and the whale blows. At the slowest speed the snout seems mostly 

 to remain beneath the surface. The blowing over, the head is lowered as the dorsal fin emerges, so 

 that for a split second both show above water (Fig. ib\ PL XXXIII, figs, i, 2). The whole body 

 then sinks, and the whale, still comparatively horizontal, submerges. This leisurely blowing (7I sec.) 

 gives a smaller target than the hurried movement. 



(ii) Medium speed. Whales may be considered to be breaking surface at medium speed (5|-6| sec.) 

 when, as frequently happens, they approach the surface at an angle of 25-35° 5 ir^ this action they can 

 also be seen for some moments before emergence and at this angle their attitude bears some resemblance 

 to a tadpole gulping air at the surface of a pond. The tip of the snout is first seen and an appreciable 

 extent (say one-third to one-half or more) of the lower jaw emerges (fig. id, e, and also True, 1903, 

 plate XXIV, fig. 2). In head-on view the white chin and the ventral grooves are plainly visible from 

 the catcher's bows. As soon as the blowhole is free the whale blows ; but as it does so the head is 

 dipped. As the head becomes horizontal, the upper jaw and, if visible, the whale-bone plates, are 

 above the surface but the lower jaw is awash. The eye appears to be hidden by the wash which the 

 lower jaw sets up. Further dipping of the head bends the anterior part of the body into an arc and as 

 the whale moves forward the blowhole disappears from view (Fig. if, g ; Plate XXXIII, figs. 3, 4). All 

 this has happened in a surprisingly short time and constitutes stage i . 



The tip of the dorsal fin may break surface before the back is wholly out of the water, but the fin 

 and blowhole are seldom visible together (Fig. i^). The whale illustrated in Plate XXXIII, fig. i, 

 while showing both blowhole, fin and peduncle, appears to be swimming more horizontally and rather 



1 The word ' blow ' is used throughout this account for the act of expiration and inspiration. It is synonymous with ' spout ' 

 which, however, is open to confusion with the traditional idea of a spouting column of water. 



