Search results
Results from the WOW.Com Content Network
The mantle cavity is a central feature of molluscan biology. This cavity is formed by the mantle skirt, a double fold of mantle which encloses a water space. This space contains the mollusk's gills, anus, osphradium, nephridiopores, and gonopores. The mantle cavity functions as a respiratory chamber in most mollusks. In bivalves it is usually ...
The mantle cavity, a fold in the mantle, encloses a significant amount of space. It is lined with epidermis, and is exposed, according to habitat , to sea, fresh water or air. The cavity was at the rear in the earliest molluscs, but its position now varies from group to group.
Siphons in molluscs are tube-like structures in which water (or, more rarely, air) flows. The water flow is used for one or more purposes such as locomotion, feeding, respiration, and reproduction. The siphon is part of the mantle of the mollusc, and the water flow is directed to (or from) the mantle cavity. A single siphon occurs in some ...
Water enters the mantle cavity through the apical aperture, and is wafted along the body surface by cilia. There are no gills; the entire surface of the mantle cavity absorbs oxygen from the water. Unlike most other molluscs, there is no continuous flow of water with a separate exhalant stream.
The males release their spermatozoa from their mantle cavity in the form of sperm balls. These balls dissolve in the water into free floating sperm. The female's eggs are fertilized in the mantle cavity (brooding chamber) when spermatozoa are filtered into her gill slits from the surrounding water.
In some nudibranchs, the mantle cavity and the original gill have disappeared altogether. Instead, the upper surface of the body has numerous club-shaped or branched projections called cerata that function as secondary gills. Secondary gills are also present in the unrelated genus Patella, in which they are found as folds within the mantle cavity.
Many marine gastropods are burrowers, and have a siphon that extends out from the mantle edge. Sometimes the shell has a siphonal canal to accommodate this structure. A siphon enables the animal to draw water into their mantle cavity and over the gill. They use the siphon primarily to "taste" the water to detect prey from a distance.
Although chitons lack osphradia, statocysts, and other sensory organs common to other molluscs, they do have numerous tactile nerve endings, especially on the girdle and within the mantle cavity. The order Lepidopleurida also have a pigmented sensory organ called the Schwabe organ. [26]