wear your heart on your sleeve. to make your feelings and opinions obvious to other people John's always worn his heart on his sleeve, so there's no doubt who he'll be supporting. See also: heart, on, sleeve, wear. Related vocabulary: wear something on your sleeve.
In many bivalves and snails, and in cephalopods, part of the mantle is modified into a siphon, which can be used to pump water through the mantle cavity for respiration, feeding and/or jet propulsion. Freshwater and marine mollusks have gills (called ctenidia) for respiration, located in the mantle cavity. In most bivalves, these are enlarged and serve to trap food particles as well (Morton 1983).
The mantle covers the body organs, which are located in the visceral mass. Between the soft body and the mantle is a space called the mantle cavity. Mollusks contain gills. Gills are organs in which carbon dioxide from the mollusk is exchanged for oxygen in the water.