On the occurrence of diatoms on the skin of whales

Abstract

In the course of my official duties during whaling operations at the South Shetlands and the South Orkneys, extending over four seasons between 1913 and 1919, I have observed that whales, and particularly the very fat individuals, are frequently covered with a film of a buffish colour. This film is easily removed, but owing to the excessively dirty conditions under which whaling is carried out, it is not an easy matter to obtain it free from admixture with other substances. The Blue Whale ( Balœnoptera musculus ) and the Fin Whale { B.physolus ) are species which are often thus coated. The film is equally thick on all parts of the skin, and it is easily seen on the white parts of the body. It is not nearly so obvious against the background of the darker parts of the skin, where it may easily be overlooked. A Blue Whale in this condition is known to the whalers as a “Sulphur-bottom.” It did not at first occur to me to investigate the cutaneous coating in question, but on examining microscopically, with a low power, a portion from a Fin Whale killed at the South Shetlands late in the season 1918-1919, I found it to consist of large numbers of what appeared to me to be Diatoms. When fresh, each of these organisms was seen to contain a yellowish speck of what seemed to be oil, near its centre. A small quantity of the film removed later from the skin of a Blue Whale, killed at the same locality, proved to agree closely, in its microscopical characters, with what had already been studied in the Fin Whale.