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Walking on penguin1 eggshells on this Moment of Science. Yael: Today, we're talking penguin eggs.
Don: Why?
Y: Penguins2 lay their eggs on hard surfaces near coastlines, or they might dig burrows3 if the soil permits. And because they're optimized4 for swimming rather than walking, it's difficult for penguins to gather a lot of soft nesting material. See the problem?
D: Hmm! the penguin lifestyle isn't exactly eggshell-friendly.
Y: And that's not counting the nasty fights penguins can get into over things like space for their nests or burrows, and the stones that some species pile up around their nests if they're in the open.
D: I bet all that hubbub5 isn't very good for eggs either. So do penguins lose more eggs than other species?
Y: Actually, according to one study, only 2.6 percent of penguin eggs break from causes other than human interference or predators6. That rate is similar to the rate in the rest of the bird world, even including those birds that have cushy nests and never fight near their eggs.
D: So how do they do it? By producing thicker shells?
Y: Yep. Penguin eggshells are fifty percent thicker than expected for their size. But it isn't easy to produce thick egg shells. It requires a lot of calcium7, more than female penguins normally get in their diets.
D: And they can't just run to the store for a supplement.
Y: Nope. So in the period right before they lay eggs, female penguins eat a lot of mollusks. The clam8 and mussel shells in their stomachs slowly leach9 calcium which is then used to form eggshells. Incidentally, thicker shells also help prevent breakage for birds that lay eggs on rocks, and for ostriches10 and rheas.
D: I always did wonder about those ostriches.
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1 penguin | |
n.企鹅 | |
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2 penguins | |
n.企鹅( penguin的名词复数 ) | |
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3 burrows | |
n.地洞( burrow的名词复数 )v.挖掘(洞穴),挖洞( burrow的第三人称单数 );翻寻 | |
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4 optimized | |
adj.最佳化的,(使)最优化的v.使最优化,使尽可能有效( optimize的过去式和过去分词 ) | |
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5 hubbub | |
n.嘈杂;骚乱 | |
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6 predators | |
n.食肉动物( predator的名词复数 );奴役他人者(尤指在财务或性关系方面) | |
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7 calcium | |
n.钙(化学符号Ca) | |
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8 clam | |
n.蛤,蛤肉 | |
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9 leach | |
v.分离,过滤掉;n.过滤;过滤器 | |
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10 ostriches | |
n.鸵鸟( ostrich的名词复数 );逃避现实的人,不愿正视现实者 | |
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