This is because they're ectotherms, meaning their bodies rely on external things for heat.

这是因为乌龟属于变温动物，也就是说，它们的身体依靠外部环境获取热量。

Is this turtle an ectotherm, or an endotherm?

这只乌龟是变温动物还是恒温动物？

By contrast, the bones of ectotherms grow more slowly and have fewer of these canals.

相比之下，变温动物的骨骼生长得更慢，而且这些骨沟更少。

This sets them apart from ectotherms, or so-called cold-blooded animals – like most fish, reptiles, amphibians, and invertebrates.

这使它们有别于变温动物，或所谓的冷血动物——就像大多数鱼类、爬行动物、两栖动物和无脊椎动物一样。

In the end the answer whether dinosaurs were ectotherms or endotherms is much more complicated than it seems.

最后，恐龙是变温动物还是恒温动物的答案比看起来要复杂得多。

Archaeopteryx, on the other hand, did have rings, indicating that it was slow-growing and was probably more of an ectotherm.

另一方面，始祖鸟确实有环，表明它生长缓慢，可能更像是一种变温动物。

This difference in temperature-regulation means that endotherms can live in more variable environments and are usually more active than ectotherms.

这种温度调节的差异意味着吸热动物可以生活在更多变的环境中，并且通常比外温动物更活跃。

As head of ectotherms, he is in charge of almost 60% of the animals in the entire zoo, but often creatures that have almost zero scientific information known about them.

作为变温动物的负责人，他管理着整个动物园近 60% 的动物，但这些动物的科学信息几乎为零。

They found that, in all cases, the nasal passages were too narrow to have respiratory turbinates and instead they more closely resembled those of ectotherms.

他们发现，在所有情况下，鼻道都太窄而没有呼吸鼻甲，相反，它们更像外温动物的鼻甲。

It turns out that this turtle is more endotherm like than ectotherm like, and is able to maintain a relatively stable internal body temperature.

事实证明，这只乌龟更像是恒温动物，而不是外恒温动物，能够保持相对稳定的体内温度。

Thanks to extensive studies on modern animals, we know that these bone cells or Osteons, are laid down in distinctive and different ways by endotherms and ectotherms.

由于对现代动物的广泛研究，我们知道这些骨细胞或骨细胞是由吸热动物和变温动物以独特和不同的方式产生的。