Takemae Nobuhiro, Nakaya Fumio, Motokawa Tatsuo
W3-42, Department of Biological Sciences, Graduate School of Bioscience & Biotechnology, Tokyo Institute of Technology. O-okayama 2-12-1, Meguro, Tokyo 152-8551, Japan.
Biol Bull. 2009 Feb;216(1):45-54. doi: 10.1086/BBLv216n1p45.
The energy consumption of echinoderms is low in comparison with that of other invertebrates. We demonstrated this by measuring the oxygen consumption rate per unit of body weight (VO2) of the sea cucumber Actinopyga mauritiana: VO2 was 1/8 that of the "standard" invertebrates. Low energy consumption in echinoderms has been attributed to their high skeletal content and to catch connective tissues (CCTs) that maintain body posture by altering their mechanical properties with little energy expenditure. The former is not applicable to holothurians, and the latter has not been proven experimentally. We postulated that the large content of dermal connective tissue, which maintaines posture economically, contributes to the low energy consumption in holothurians. Body-wall dermis occupied 53.5% of wet body weight, whereas body-wall muscles, including those of tube feet, occupied 5.1%. VO2 of the dermis in the stiff state (2.45 microl x g(-1) x h(-1)) was 1/10 that of the longitudinal body-wall muscle in contraction. the mechanical tests revealed that the stress at an imposed strain of 2% strain was 7 times greater in CCT than in muscles. These results showed that CCT could maintain posture more economically than muscles could. We concluded that the high content of connective tissue with energy-saving posture-maintenance activities contributed to the low energy consumption of holothurians.
与其他无脊椎动物相比，棘皮动物的能量消耗较低。我们通过测量糙海参单位体重的耗氧率（VO2）来证明这一点：VO2是“标准”无脊椎动物的1/8。棘皮动物的低能量消耗归因于其高骨骼含量以及捕捉结缔组织（CCTs），后者通过很少的能量消耗改变其机械性能来维持身体姿势。前者不适用于海参，而后者尚未得到实验证明。我们推测，大量能经济地维持姿势的真皮结缔组织有助于海参的低能量消耗。体壁真皮占湿体重的53.5%，而包括管足肌肉在内的体壁肌肉占5.1%。处于僵硬状态的真皮的VO2（2.45微升×克-1×小时-1）是收缩状态下纵向体壁肌肉的1/10。力学测试表明，在施加2%应变时，CCT的应力比肌肉大7倍。这些结果表明，CCT比肌肉能更经济地维持姿势。我们得出结论，具有节能姿势维持活动的结缔组织含量高有助于海参的低能量消耗。
