A simple technique for preservation and staining of the delicate houses of oikopleurid tunicates

Abstract

The houses of oikopleurid larvaceans are of such a delicate structure that their preservation and storage for reference collections and post-collection study has been essentially impossible. However, houses ofOikopleura dioica, O. labradoriensis andO. vanhoeffeni, ranging in size from 0.7 to 7 cm, may be dried onto glass slides or onto paper or membrane filters so that most structural details are maintained. The handling of houses during the drying process is greatly facilitated if they are prestained by particulate or colloidal dyes while still inhabited. Such staining also reveals a wealth of structural detail that is difficult to obtain by other means. Staining the house after mounting and drying is also possible, but more difficult. The described technique may be used for making permanent records of oikopleurid houses of all sizes, from the first post-metamorphic house of <1 mm diameter to the largest known oikopleurid house of perhaps 1 m diameter. Such records may serve both as taxonomic tools and as specimens for detailed structural and chemical analysis by high-power microscopes and microbeam instruments.