X.—On the Feeding Mechanism of a Mysid Crustacean, Hemimysis Lamornæ

Abstract

The general biology of the Mysids has recently been studied at great length by Blegvad (1922) at Copenhagen. His paper, containing a very complete literature list, deals with Mysis inermis, Rathke, Mysis flexuosa, Müller, and Mysis neglecta, Sars. His comments on feeding are limited, and refer chiefly to the nature of the food that the animals ate in captivity. Gelderd's work (1909) on the digestive system of the Schizopoda describes the course taken by the food through the gastric mill, the masticatory functions of this apparatus, and the method by which the masticated food and digestive juices are brought together, but does not deal with the manner in which the food reaches the stomach. An account, then, of the method by which a mysid collects its food would fill a gap in our knowledge of these forms. The only description, as far as we are aware, of the feeding habits of a mysid is that of Depdolla (1923), who worked on Praunus [Mysis] flexuosus, but his account is superficial and in our opinion very inaccurate. The following paper deals with the feeding habits of a small mysid, Hemimysis lamornœ, about 8 mm. long, which has established itself in the larger fish-tanks at the M.B.A. laboratory at Plymouth. It breeds freely all the year round, and can be obtained from the tanks in abundance, although it is stated to be only a rare visitor in the Plymouth district.