Office of Training & Education 2. Â§1926.450 - SUBPART L. âUpdates the existing standard to include types of. scaffolds such as catenary and step and trestle. âAllows flexibility in the use of fall protection. systems to protect employees. âSimplifies language, eliminates duplicative, outdated provisions, consolidates overlapping. requirements.
Two whole shells, one closed and one open, of the marine bivalve Abra alba. Live marine venerid cockles, Austrovenus stutchburyi from New Zealand. A bivalve shell is part of the body, the exoskeleton or shell, of a bivalve mollusk.In life, the shell of this class of mollusks is composed of two hinged parts or valves. Bivalves are very common in essentially all aquatic locales, including saltwater, brackish water, and freshwater.wo whole shells, one closed and one open, of the marine bivalve Abra alba. Live marine venerid cockles, Austrovenus stutchburyi from New Zealand. A bivalve shell is part of the body, the exoskeleton or shell, of a bivalve mollusk.
The main muscle of a bivalve is called the adductor muscle, and is also used to hold the shell halves together. When the bivalve s adductor muscles relax, the ligament causes the valves to open. Most species are also equipped with locking teeth or sockets beneath the ligament to prevent lateral slippage.ther ancient bivalves appear to have a double set of gills. The second sets of gills actually arise from a folding of the single gill. This is the case in the Filibranchia and Eulamellibranchia, where the gills have also taken over the function of obtaining food.