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 11 hard defenses DHJanzen100250.jpg high resolution
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| Clams, snails, oysters, scallops, limpets, barnacles, nautilus, brachiopods - they have all gone the way of the turtle. While many do have their behavioral escapes as well (hiding, swimming, squirting away, crypsis, etc.), in contrast to terrestrial animals they have incorporated a hard case in their defense repertoire in a major way. And, they have become (or were to begin with) highly sessile - again, like plants. This pearl oyster, as everyone knows who has eaten a raw oyster, has essentially no defenses other than its hard container. I should note that while such edibility is commonplace for animals in hard containers (and, may I add, seeds in hard nuts as well), it is not universal. There are a few chemically defended marine molluscs (though such defense may well have begun as part of its predation tools, such as cone snails). But, in general, the marine molluscs that are aposematic or otherwise suspected of being inedible have also dropped or reduced their shell production as a defense. | ||
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