The feeding mechanism of the oyster. II. On the gills and palps of Ostrea edulis, Crassostrea virginica and C. angulata

205

179

A large number of suspension-feeding aquatic animals (e.g. bivalves, polychaetes, ascidians, bryozoans, crustaceans, sponges, echinoderms, cnidarians) have specialized in grazing on not only the 2 to 200 µm phytoplankton but frequently also the 0.5 to 2 µm free-living bacteria, or they have specialized in capturing larger prey, e.g. zooplankton organisms. We review the different particle capture mechanisms in order to illustrate the many solutions to the common problem of obtaining nourishment from a dilute suspension of microscopic food particles. Despite the many differences in morphology and living conditions, particle capture mechanisms may be divided into 2 main types. (1) Filtering or sieving (e.g. through mucus nets, stiff cilia, filter setae), which is found in passive suspension feeders that rely on external currents to bring suspended particles to the filter, and in active suspension feeders that themselves produce a feeding flow by a variety of pump systems. Here the inventiveness of nature does not lie in the capture mechanism but in the type of pump system and filter pore-size. (2) A paddle-like flow manipulating system (e.g. cilia, cirri, tentacles, hair-bearing appendages) that acts to redirect an approaching suspended particle, often along with a surrounding 'fluid parcel', to a strategic location for arrest or further transport. Examples include (1) sieving (e.g. by microvilli in sponge choanocytes, mucus nets in polychaetes, acidians, and salps among others), filter setae in crustaceans, 'ciliary sieving' by stiff laterofrontal cilia in bryozoans and phoronids; and (2) 'cirri trapping' in mussels and other bivalves with eu-laterofrontal cirri, ciliary 'catch-up' in bivalve and gastropod veliger larvae, some polychaetes, entroprocts, and cycliophores. These capture mechanisms may involve contact with a particle, and possibly mechanoreception or chemoreception, or may include redirection of particles by the interaction of multiple currents (e.g. in scallops and other bivalves without eu-laterofrontal cirri). Based on the review, we discuss the current physical and biological understanding of the capture process and suggest a number of specific problems related to particle capture, which may be solved in the future using advanced theoretical, computational and experimental techniques.

Section: Suspension-feeding Without Laterofrontal Cirrimentioning

confidence: 99%

Particle capture mechanisms in suspension-feeding invertebrates

Riisgård¹,

Larsen²

2010

205

179

“…1 & 3). This median ridge, depicted in Nelson (1960), is formed by the contraction of muscles beneath the epithelium of the PF trough (Fig. 1).…”

Section: Zone Lmentioning

confidence: 99%

“…A detailed endoscopic study of particle transport in the heterorhabdic pseudolamellibranch Crassostrea virginica was performed by Ward et al (1994) et al (1993) "Gill types for which both endoscopic and rnucocyte distribution data are available '"'Gill types for which endoscopic data only are available the performance of which functions, nor can it identify the sites of such secretion and the relative importance of these secretions in specific areas of the gill. Aiiiiuuyh some qualitative information exists concerning the relative abundances of mucocytes in the gills of Crassostrea virgjnjca (Ribelin & Collier 1977) and the European oyster Ostrea edulis (Owen 1978), kkLc q,,.,-+.+ uuti,ii.aLJ.vc +;..-data are the results of Nelson (1960) indicating 'average' mucocyte numbers for the entire gill in histological sections for 3 oyster species. A thorough understanding of the mechanism of particle transport in the heterorhabdic pseudolamellibranch gill of the Ostreidae requires a more detailed and quantitative approach to mucocyte distribution and secretion type.…”

Section: Introductionmentioning

confidence: 99%

Mucocyte distribution and relationship to particle transport on the pseudolamellibranch gill of Crassostrea virginica (Bivalvia:Ostreidae)

Pg¹,

Sc²

1996

To investigate particle transport mechanisms on the bivalve pseudolamellibranch gill, the mucocyte secretion types and distribution were determined for this organ in the eastern oyster Crassostrea virginica, and related to previous endoscopic data. Three adult oysters were collected from Shediac Bay (New Brunswick, Canada) in July 1994, immediately fixed, then dissected and processed for histology and whole mount rnucocyte mapplng uslng a modification of the penodic acidSchiff-alcian blue protocol. One type of mucocyte contained acid-secretion rnucopolysaccharides (AMPS), while the other type contained neutral rnucopolysaccharldes (NhIPS). A clear grad~ent in nlucocyte density was observed from the plical crest to the trough; for all but the anteriorn~ost 15 plicae the proportions of each mucocyte type remained constant; the 15 anteriormost plicae presented an increased proportion of AMPS. These proportions would produce a relahvely viscous acid-dominant mucus after mixing on the c~liated gill surfacr. The principal filament troughs contained relatively few Inucocytes, aligned on the median ndge This arrangement could account for the observed range of partlcle velocities in these filaments. The results of the present study conform to a pattern of specialization of nlucus types and functions on the diverse types of bivalve gill, depending on particle trajectory, transporting surface architecture, and dominant current flow.

“…Earlier authors have pointed to the labial palps as the site of particle selection (e. g. Owen, 1966;Purchon, 1968), and indicated that the size of the palps is an adaptation to the particle concentrations encountered by the bivalves in their natural habitats (e. g. Nelson, 1960;Ansell, 1961;Theisen, 1977). We have therefore compared the measured selection efficiencies with the size of the palps, both within and between species.…”

Section: Introductionmentioning

confidence: 99%

Particle Selection in Suspension-Feeding Bivalves

Kiørboe¹,

Møhlenberg²

1981

246

Particle selection was studied in 10 species of suspension-feeding bivalves by comparing the proportion of algae in the pseudofaeces with that in the surrounding water. All species examined exhibited particle selection, but with different efficiencies. Spisula subtruncata was most efficient, followed, in decreasing order of efficiency, by Corbula gibba, Mytilus edulis (from Wadden Sea), Acanthocardia echjnata, Aequipecten opercularis, Musculus niger, Crassostrea gigas, Mya arenaria, Cerastoderrna edule, Mytilus e d u l~s (from Qresund), and Arctjca ~slandica. Selection efficiency correlated with the size of the labial palps. Particles rejected as pseudofaeces were embedded in mucus, whereas ingested particles were always in free suspension in M. edulis. Apparently, then, different particles have different probabilities of being trapped in mucus, and thus rejected as pseudofaeces. The properties which determine this probability are unknown.