Ciliary and mucus-net filter feeding, with special reference to fluid mechanical Characteristics

Abstract

Filter characteristics have been determined and compared in ciliary and mucus-net filter feeders. The ciliary feeders include the polychaete Sabella penicillus, the brachiopod Terebratulina retuso, the marine bivalves Monia squama, Cardiurn glaucum, and Petricola pholadiformis, and the freshwater bivalves Dreissena polymorpha, Unio pictamrn, and Anodonta cygnea. The mucus-net feeders are the polychaete Chaetopterus variopedatus, the gastropod Crepidula fomicata, and the ascidians Sfyela clava, Ciona intestinalis, Ascidia virginia, Ascidia obliqua, and Ascidia mentula. Efficiencies of particle retention as a function of particle size was determined by counting of particles in samples of inhalant and exhalant water. The lower threshold for efficient particle retention varied from about 6 p m in T. retuso to about 1 p n in D. polyrnorpha. Mucus nets efficiently retained particles down to 1 to 2 pm. Filter feeding is characterized by processing of water at low pressures (5 l mm H,O). Mechanisms of water processing and particle retention in brachiopods and bivalves are compared. It is concluded that laminar flow of through-currents and surface-currents in brachiopods is consistent with the hypothesis of capture of suspended particles by means of viscous forces acting upon the particles in the zone of contact between the 2 flow systems.

Downstream collecting in ciliary suspension feeders: the catch-up principle

“…A rather similar pattern for the lower end of the retention spectrum, as determined for bivalve veliger larvae (Fig. 17), has been found for the adult polychaete Sabella penicillus by Jørgensen et al (1984), who measured 30% lower clearance of about 1 µm particles compared to the clearance of 3 to 3.5 µm diameter particles; but also notable in this connection, the relative clearance declined only slightly for larger particles up to 8 µm diameter (Fig. 18).…”

“…Upper: cross section of 2 pinnules with opposed compound lateral cilia in resting position at the end over recovery stroke, clc (1), and end of active stroke, clc (2); (fc, frontal cilia) (from Riisgård & Ivarsson 1990). Lower: retention spectrum expressed as relative clearance of particles of different sizes measured on the adult polychaete (from Jørgensen et al 1984) either not be caught-up or it is liable to roll off a single pushing cilium to subsequently be lost with the through flowing water. The lower size limit for retention of particles by ciliary downstream suspension feeders seems to be fixed and nearly identical for all species studied (i.e.…”

Filtration Rates of the Zebra Mussel ( Dreissena polymorpha ) on Natural Seston from Saginaw Bay, Lake Huron

“…1989;Reeders and bij de Vaate 1992;Stanczykowska and Lewandowski 1993). As a suspension feeder, Dreissena filters particles from the water column, retaining nearly 100% of the particles > 1 /lm (Jorgensen et al 1984). Some of this particulate material is ingested, while a portion is rejected and deposited on the bottom as pseudofeces.…”

Form and function in juvenile ascidians. I. Implications of early juvenile morphologies for performance

“…Much of their morphology can be linked to functions related to active suspension feeding, which has been studied extensively in adult ascidians and bivalves (e.g. FialaMedioni 1978, Flood & Fiala-Medioni 1979, Randløv & Riisgård 1979, Jørgensen et al 1984, Riisgård 1988, Petersen & Riisgård 1992, Riisgård & Larsen 1995, Kowalke 1999, Petersen & Svane 2002. The physical mechanisms of flow generation during active suspension feeding are well understood, and the effects of morphology and size on feeding performance are readily quantifiable (Rubinstein & Koehl 1977, Jør-gensen et al 1984, LaBarbera 1984, Riisgård 1988.…”