Dorsal

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Definition

  • according to Hottinger (2006):

DORSAL - the side of a free, flattened organism turned away from its substrate, as opposed to ventral.

Remarks: Revets (1994) rightly points out that the terms dorsal and ventral, beyond their specific meaning in the architecture of vertebrates, refer to the orientation of a flattened organism in respect to its substrate. In foraminifera, benthic, free shells live with their apertural face on their substrate in order to gather food. Permanently attached shells, usually filter feeders, are living with their apertures turned away from the substrate. They must have free apertures in order to add new chambers during growth. In most free, trochospiral forms, the spiral side is in a dorsal, the umbilical side in a ventral position. Nepionic, spiral stages in permanently attached forms (Planogypsina (Cibicididae) for instance) show by the position of their foramina in the early spiral whorl that their surface of attachment is on their spiral (dorsal) side. However, in current usage the terms dorsal-ventral and spiral-umbilical respectively may not always be synonymous.

See also

References

Hottinger (2006), Illustrated glossary of terms used in foraminiferal research. Carnets de Géologie, Memoir 2, ISSN 1634-0744

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