calcareous shell造句

• Most reptiles lay amniotic eggs covered with leathery or calcareous shells.
• Their coiled, calcareous shell has a diameter of less than 1 cm.
• These semi-rigid structures are part of the periostracum, a thin protein layer ( conchiolin ) secreted by the snail to cover the calcareous shell.
• The "'Articulata "'is a class of brachiopods which comprises those with hinged, calcareous shells that generally bear well developed teeth and sockets and a simple muscle system.
• Calcium carbonate becomes more soluble at lower pH, so ocean acidification is likely to affect marine organisms with calcareous shells, such as oysters, clams, sea urchins and corals, and the carbonate compensation depth will rise closer to the sea surface.
• Many benthic mollusks have planktonic larvae called veligers that have calcareous shells, and these larvae are particularly vulnerable to changes in water chemistry; their shells are so thin that small changes in pH can have a large impact on their ability to survive.
• In 2011, researchers suggested that " extant marine invertebrates face the same synergistic effects of multiple stressors " that occurred during the end-Permian extinction, and that genera " with poorly buffered respiratory physiology and calcareous shells ", such as corals, were particularly vulnerable.
• The shell-less aplacophora have a chitinous cuticle that has been likened to the shell framework; it has been suggested that tanning of this cuticle, in conjunction with the expression of additional proteins, could have set the evolutionary stage for the secretion of a calcareous shell in an aplacophoran-like ancestral mollusc.
• As small organisms with hard, calcareous shells have trouble growing at extreme depths because of the high solubility of calcium carbonate in the pressurized water, scientists theorize that the preponderance of soft-shelled organisms in the Challenger Deep may have resulted from the typical biosphere present when the Challenger Deep was shallower than it is now.
• "H . pomatia " eggs measure about 3 mm in diameter and have a calcareous shell and a high yolk content . " H . pomatia " lays the eggs in July or August, 2 to 8 weeks after mating, in holes dug out in the ground . ( Data varies widely on how long after mating snails lay eggs . ) The snail puts its head into the hole or may crawl in until only the top of the shell is visible; then it deposits eggs from the genital opening just behind the head.