One important concept is that typically used reinforcing (post-tensioning tendons and shrinkage-compensating concrete reinforcement are the exceptions) will not prevent the concrete from cracking. The reason for this is that the reinforcing cannot begin to start resisting significant tension until the concrete cracks.
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.he mantle also secretes the shell, in those mollusks that have one. In many gastropods and cephalopods, the mantle is brightly colored and important for communication. In giant clams, the outer mantle tissue is colonized by symbiotic algae that provide their host with food energy in exchange for shelter.
Mollusca Worksheet 1. For what purpose do mollusks use their muscular foot? 2. How is the muscular foot of a squid different from that of clams and snails? 3. What is a mantle and where is it located in most mollusks? 4. What is contained in the visceral mass? 5. How do most sessile and burrowing mollusks obtain food? 6. What kind of digestive tract do mollusks have? 7. How do the nervous systems of clams and octopuses differ? 8. How do mollusks reproduce; sexually, asexually, or both? 9. Where does fertilization take place in mollusks?