Vol. 27: 79-86, 1985
Published November 14

MARINE ECOLOGY - PROGRESS SERIES

Ultrastructure of the mucous feeding filter of the
house of the appendicularian Oikopleura
vanhoeffeni


Don Deibel, 1, M.-L. Dickson 1, 2 & 3, C.V.L. Powell 2


1 Newfoundland Institute for Cold Ocean Science,
2 Dept. of Biology, and
3 Marine Sciences Research Laboratory.
Memorial University of Newfoundland, St. John's, Newfoundland A1C 5S7, Canada


ABSTRACT: Transmission electron microscopy was used to investigate the pore size and fiber diameter of the feeding filter of the house of Oikopleura vanhoeffeni. Quantitative information on the ultrastructure of the filter is necessary to investigate particle retention efficiency and fluid mechanics of feeding. Specimens were collected by hand from April to July of 1983 and 1984 in Logy Bay, Conception Bay, and Bay Bulls, Newfoundland. The feeding filter consisted of a rectangular array of 3 types of fibers: smooth, nodulated, and microfibers. There were nodes at points where nodulated fibers and microfibers crossed. The distance separating smooth fibers was variable (1 to 12 µm). All 3 types of fibers formed branches. Mean pore size of the filter was 1.04 ± 0.26 (n=223) X 0.22 ± 0.04 µm (n=502; ± SD). Smooth and nodulated fibers were about 40 nm in diameter, and microfibers about 12 nm. The % open area (porosity) of the feeding filter was 91 %. The large surface area and high porosity of the feeding filter allow O. vanhoeffeni to maintain a high volume flow per unit time while concentrating food with a mucous net of small pore size.