Saz H J
Annu Rev Physiol. 1981;43:323-41. doi: 10.1146/annurev.ph.43.030181.001543.
Many metazoans, and particularly the parasitic forms, have adapted well to their environments. This is particularly obvious in organisms that reside in anoxic surroundings, such as the large lumen-dwelling intestinal parasites. However, anaerobic energy metabolisms are not confined to parasites in microaerophilic environments. Some that reside in highly aerobic surroundings (e.g. blood or lungs) also have lost much or all of their aerobic capabilities for energy generation. Adaptations toward anaerobiosis are many and varied: homolactate fermentation (schistosomes and filarial worms), heterolacate fermentations (H. diminuta), and succinate and heterosuccinate fermentations (Ascaris). Even helminths that are obligate aerobes are not complete oxidizers. All accumulate aerobic fermentation products, indicating at best a limited terminal respiration. Some worms, particularly some of the larval stages, retain their ability to survive anaerobically but require the presence of oxygen for motility. Regardless of the type of oxygen requirement, all parasitic helminths examined are dramatically different from their mammalian hosts in regard to their energy metabolisms. Many similar adaptations have been shown to occur in nonparasitic organisms ranging from metazoans, through fish and mammals. There is much room for additional studies of these biochemical adaptations.
许多后生动物，尤其是寄生形式的动物，已经很好地适应了它们的环境。这在生活在缺氧环境中的生物中尤为明显，比如寄居于肠道大管腔中的寄生虫。然而，无氧能量代谢并不局限于微需氧环境中的寄生虫。一些生活在高度需氧环境（如血液或肺部）中的寄生虫也已经丧失了大部分或全部的有氧能量生成能力。对无氧生活的适应方式多种多样：同型乳酸发酵（血吸虫和丝虫）、异型乳酸发酵（微小膜壳绦虫）以及琥珀酸和异琥珀酸发酵（蛔虫）。即使是专性需氧的蠕虫也不是完全的氧化者。它们都会积累有氧发酵产物，这表明它们的末端呼吸能力充其量是有限的。一些蠕虫，特别是某些幼虫阶段，保留了无氧生存的能力，但运动需要氧气。无论对氧气的需求类型如何，所有被研究的寄生蠕虫在能量代谢方面都与它们的哺乳动物宿主有显著差异。从后生动物到鱼类和哺乳动物等非寄生生物中也已发现许多类似的适应性变化。对这些生化适应性的进一步研究还有很大空间。
