COMMON FINBACK WHALE. 233 



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Enemies and Parasites. 



In our waters, the larger whales seem to have little to fear from other predatory creatures. 

 Xo doubt the fierce Orca or Killer Whale may occasionally attack them but I have no definite 

 evidence on this matter, and the species is rare with us. 



Ordinarily the Finback Whale does not harbor any barnacles on the body surfaces, though 

 the whalemen tell me that rarely a small species resembling a common ship's barnacle is found 

 on captured specimens. 



On the plates of whalebone Lillie (1910, p. 786) has lately recorded for the first time in 

 this species, the presence of multitudes of the minute crustacean Balaenophilus unisetus Auri- 

 villius, a copepod modified for this semiparasitic existence. These minute animals reach 

 an adult size of less than four millimeters and in both young and mature stages are found cling- 

 ing in multitudes to the baleen plates. Lillie's observations were made on the Irish coast, 

 but the same parasite is to be looked for on this side of the water. 



Another copepod, Penella balaenopterae, likewise occurs as a parasite of this whale, and 

 is most remarkably modified for life with its huge host. In the earlier stages, both sexes are 

 of more or less normal appearance, with enlarged thorax, narrower abdomen, and swimming 

 appendages. The adult female, however, burrows with her head deeply into the exterior of 

 the whale, and her entire body becomes transformed into an elongated sac, the head develops 

 horn-like anchors for holding, and the remainder of the body with two long egg sacs and gills 

 trails behind in the water, some eight inches in length. Turner (1905) mentions finding numer- 

 ous specimens in the back of one of these whales. 



Of internal parasites the best known are certain so-called thorn-headed worms of the genus 

 Echinorhynchus, which attach themselves to the lining of the intestine. The sexes are separate, 

 and the larvae pass from the body of the female worm into the intestinal cavity of the whale, 

 whence they are discharged with the faeces. In many other species these young pass the next 

 stage of life as parasites in Crustacea, so it is likely that in some one or other of the minute cope- 

 pods or schizopods on which these whales feed, this second stage will be found. The crustacean 

 host is swallowed in its turn by the whale, and so allows the parasite to pass its adult stage 

 in the whale's intestine. Borgstrom (1892) was the first to report Echinorhynchus turbinella 

 from the Common Finback, and it occurs also in the Pollack Whale. A second species, E. 

 brevicollis, is lately reported from the intestine of the Finback (Hamilton, 1916, p. 132). 



Haldane records finding two or three bushels of nematode worms in the stomach of a 

 Finback, which were identified by Von Listow as Ascaris simplex, a species that also occurs 

 in the Harbor Porpoise. In the intestines of Fin Whales killed from the Belmullet Whaling 

 Station on the Irish coast, Hamilton (1915, 1916) has lately reported finding numbers of the 

 trematode, Monostomum plicaium. 



