Stages in the Development of the Stickleback Gasterosteus aculeatus (L.)

ABSTRACT Much good work has been done on the developmental morphology of the teleostean fishes from the works of Ryder (1884), Cunningham (1886), and McIntosh & Prince (1890) onwards. With the advent of experimental embryology the need for tables of development of different species was felt. Meek (1924), Ballantyne (1930), and Oppenheimer (1937) provide some normal tables for the teleosts Gadus, Callichthys, and Fundulus respectively, but much work is still needed on other species which are suitable for experimental work. Gasterosteus aculeatus, the three-spined stickleback, has become a laboratory fish because of its small size, easy availability, wide distribution, and very interesting breeding habits. This fish breeds mainly during April and May, but it is possible in the laboratory to bring it into breeding condition during most of the year. The factors controlling the time of reproduction are intensity of light and amount of food. When the author began experimental work on G. aculeatus it was soon realized that no complete table of normal development of this fish exists. Kuntz & Radcliffe (1917) described only a few stages, and though Vrat (1949) has given the main stages, he has omitted many important developmental features. A more detailed account of the development of this fish has therefore been prepared.