Velum


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Related to Velum: velum interpositum

velum

[′vē·ləm]
(biology)
A veil- or curtainlike membrane.
(invertebrate zoology)
A swimming organ on the larva of certain marine gastropod mollusks that develops as a contractile ciliated collar-shaped ridge. Also known as veil.
(meteorology)
An accessory cloud veil of great horizontal extent draped over or penetrated by cumuliform clouds; velum occurs with cumulus and cumulonimbus.

Velum

 

(1) An organ of locomotion and seizing food in medusae, siphonophores, and the larvae of many marine mollusks (veligers). In medusae and in the floating bells of the siphonophores, the velum is an overhanging border edging of the umbrella. Because of contraction of the circularly placed epithelial-muscle (in medusae) or muscle (in siphonophores) cells, the velum is pressed against the interior surface of the umbrella and, by expelling water from under it, causes locomotion of the animal. In veligers the velum, located at the front end of the body, resembles a fringed disk, often of complex form and covered with cilia.

(2) A fold of the mucous membrane in the lancelet that divides the preoral hood from the pharyngeal cavity.

velum

Same asVelarium.
References in periodicals archive ?
velum that are as young as 11 days postfertilization and which are still developing inside the egg capsule.
The use of PCR in combination with primers identical to the Solemya velum symbiont RubisCO gene made it possible to establish the presence or absence of symbionts in host tissues and thereby test for vertical transmission of symbionts in this clam.
velum symbiont RubisCO gene was consistently amplified from DNA extracted from female clam ovarian tissue collected throughout the year, but no product was ever amplified with the same assay on samples of S.
Table I Detection of bacterial symbionts in DNA extracted from Solemya velum gonad tissue collected near Woods Hole, Massachusetts, between September 1992 and October 1993 using PCR with primers specific for the S.
velum symbionts are metabolically active, oxidizing sulfide (Chen et al., 1987) and fixing C[O.sub.2] (Cavanaugh, 1983; Cavanaugh et al., 1988) into organic carbon for the whole organism.