Ctenidia


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Ctenidia

 

the primary gills of mollusks. Each ctenidium is a bipinnate projection in the mantle cavity; it consists of an axial plate or lamella from the flat sides of which project numerous filaments covered with ciliated epithelium. Along one narrow side of the plate there is a blood vessel that brings venous blood, and on the other side there is a blood vessel that carries away oxygenated arterial blood. The number of ctenidia ranges from many pairs (in Amphineura) to a single pair (in Gastropoda and Cephalopoda), and even a single ctenidium (in many Gastropoda). The lamellar gills of bivalve mollusks are a pair of modified ctenidia.

References in periodicals archive ?
The ctenidia in combination with ventral stylets or valvulae, assist in moving the egg in the basal section of the ovipositor shaft while the valvili help in moving the egg in the terminal part of it using hydrostatic pressure for a speedy delivery of the egg into the host.
One is located at the junction of the ascending lamella of the outer demibranch (1); one runs along the axis of the ctenidia, between the outer and inner demibranchs (2); and another in the ventral groove of the inner demibranch (3).
Two long ctenidia extending length of succeeding sternite, palpus with no spine-like setae on ventral side.
The most common geoduck parasites observed on histological examination included an RLO in the ctenidia (39%; Fig.
The four trowel-shaped ctenidia as well as the combination of coloration and "crimped" male fixed finger distinguishes it from other members of the Eremobates scaber group.
In contrast, the ctenidia of marine mussels (subclass Pteriomorphia; filibranch, homorhabdic, nonplicate gills) play little role in particle selection.
pansa is an antero-posteriorly elongated organ located on the internal surface area of the mantle, that folds on its posterior side near the rectum, right of the ctenidia and anterior to the kidney.
While host worms were retracted into their tubes, snails used their ctenidia to suspension feed.
Tissues containing mantle, ctenidia, labial palps and digestive system infected with sporocysts was immediately fixed in Davidson fixative prepared with seawater.
Rather, there is growing support for viewing limpets as a divergent group (Ponder and Lindberg, 1996) whose ancestors may have had internal fertilization with introsperm, a helicoid larval shell (Page, 1994), and primitive ctenidia.
Concerning the mechanisms underlying the increased presence of dinoflagellates and chloropyta within the stomach contents of mussels from both populations, two hypothesis are at least possible: (1) these microalgae could be ingested in preference to diatoms through the differential retention in the ctenidia and/or selection during the pseudofeces forming process; (2) they would be far more resistant to extracellular digestion remaining longer within the gut and being preferentially voided with the feces.