COMPARATIVE MORPHOLOGY OF FILTERING STRUCTURE OF FIVE SPECIES OF EUPHAUSIA (EUPHAUSIACEA, CRUSTACEA) FROM THE ANTARCTIC OCEAN (Ninth Symposium on Polar Biology)

• Main Authors: Hae-Lip SUH, Takahisa NEMOTO
• Format: Report
• Language: English
• Published: Proceeding 1987
• Subjects: Antarctic; Antarctic Ocean; The Antarctic; Antarc*; Polar Biology; Proceedings of the NIPR Symposium on Polar Biology
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=5017; http://id.nii.ac.jp/1291/00005017/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=5017&item_no=1&attribute_id=18&file_no=1

Morphology of the filtering apparatus, in particular mesh size and filtering area, of five Euphausla species was investigated. Mesh sizes and filtering areas were measured utilizing an SEM. Among adult krill the filtering areas vary from 17.7 mm^2 in E. frigida to 276.8 mm^2 in E. superba. By applying sieve hypothesis, it is proposed that the presumptive lower limits of filterable particle sizes based on the morphology of fine filter meshes range 2-3 μm in E. superba, 8-11 μm in E. vallentini, 15-19 μm in E. frigida, 16-23 μm in E. crystallorophias and 27-39 μm in E. triacantha. In E. superba, the filter mesh sizes do not increase considerably with growth. In E. triacantha, the mean secondary setal distances increase from 28-37 μm to 41-56 μm. Species can be grouped according to the mesh sizes and filtering area; i) fine mesh filter feeder represented by E. superba; ii) medium mesh filter feeders such as E. vallentini, E. crystallorophias and E. frigida; and iii) coarse mesh filter feeder, E. triacantha. Potential food size spectra of these Euphausia species are discussed.