152 Memoir Sears Foundation for Marine Research 



the Atlantic specimens, there being no reason to suppose that Atlantic specimens would 

 differ very widely from those of the Pacific. Estimated weights of smaller specimens are: 

 about 6,600 pounds at about 23 feet, 1,000 to 1,800 pounds at 13 to 15 feet, and 800 

 pounds at 8 feet 4 inches.^" 



Developnental Stages. Developmental stages have not been described, except as 

 noted (p. 152). 



Habits. Basking Sharks are sluggish and inoffensive fish. When in coastwise waters 

 they spend much time lying at the surface with backs awash, their dorsal fins standing high 

 above the water with tip of snout and caudal showing; or they swim slowly, with mouth 

 open gathering their diet of plankton. They are also described as sometimes lying on their 

 backs sunning their bellies. They are so little disturbed by boats that it is easy to approach 

 them closely; in fact, excellent moving pictures of them have been taken off Ireland.^' 

 However, on occasion they are reported as jumping, perhaps in an attempt to shake off 

 remoras or parasites. They often gather in schools of up to 60 or 100 individuals and 

 there are reports of two or three swimming tandem. 



In the Gulf of Maine and off the middle Atlantic coast of the United States, as well 

 as in the northern part of their range in the opposite side of the Atlantic, Basking Sharks 

 appear almost exclusively during the warm half of the year,^^ and the early accounts sug- 

 gest some movement northward during the summer in northern European waters. The 

 winter habitat of the northern species is not known for either side of the Atlantic, although 

 lack of evidence of any increase in abundance to the southward suggests that they simply 

 retire in the fall and winter to deeper water."^ If so, the scarcity of animal plankton that 

 prevails generally in boreal seas during winter must result in very poor feeding for them, 

 suggesting that they are generally inactive at that time, perhaps lying on or close to 

 bottom. 



The only definite information as to breeding habits is the report, more than a century 

 and a half old, that an embryo about one foot long was taken from the mother." It is not 

 known at what season the young are born, for while it has been stated that their habit of 

 schooling is associated with breeding, this seems more likely connected with their pursuit 

 of planktonic food. However, it seems certain that young are produced throughout their 

 entire range, for small ones have been reported both from the north (Ireland, Norway) 

 and from the south (Mediterranean). 



The diet of the Basking Shark consists wholly of small planktonic organisms which 

 it sifts out of the water by means of its gill rakers, as do such plankton feeders as some 

 dupeoids, anchovies and whalebone whales. Usually the stomach contents are simply a 



20. An estimated weight of about 3,000 pounds for one between 12 and 14 feet long was probably far too high. 



21. In the widely popular film, "Men of Arran." 



22. A skeleton found on the beach near Provincetown, Massachusetts, in January 1939, may have been there for 

 months. 



23. On this, see Lijbbert and Ehrenbaum (Handb. Seefisch. Nordeurop., 2, 1936: 281). 



24. Pennant, Brit. Zool., 5, 1776: loi. 



