Oxygen limitation has been proposed as one of the key factors that limits body size at high temperatures (the oxygen-temperature hypothesis). Geographic patterns in body size are thought to be driven in part by the effects of temperature on oxygen supply and demand, particularly when the increased oxygen demand of tissues at higher temperatures outpaces the ability of large organisms to supply internal tissues with oxygen. We tested the effects of temperature on the rate of oxygen consumption of two temperate sea spider (Pycnogonida) species, Achelia chelata and Achelia gracilipes, across a range of body sizes. We measured oxygen consumption at 5 temperatures: 12, 16, 20, 24, and 28 °C. Oxygen consumption of both species increased significantly with temperature, but the effect did not depend on body size; thus, we found no evidence to support the oxygen-temperature hypothesis. While previous interspecific studies on Antarctic pycnogonids have found that larger-bodied animals have more porous cuticles, thus potentially offsetting their higher aerobic metabolic demand by increasing oxygen diffusivity, the pore area of the cuticle of the two temperate species did not change with body size. This suggests that the generally small size of warm-water sea spiders may be due to selective factors other than oxygen limitation.

中文翻译：

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温带海蜘蛛的体型：没有氧气温度限制的证据

氧气限制被认为是在高温下限制身体大小的关键因素之一（氧气温度假设）。体型的地理分布被认为部分是由温度对氧气供应和需求的影响驱动的，特别是当组织在较高温度下增加的氧气需求超过大型生物为内部组织供应氧气的能力时。我们测试了温度对两种温带海蜘蛛 (Pycnogonida) 物种 Achelia chelata 和 Achelia gracilipes 在不同体型的耗氧率的影响。我们测量了 5 个温度下的耗氧量：12、16、20、24 和 28 °C。两种物种的耗氧量均随温度显着增加，但其影响与体型无关；因此，我们没有发现支持氧气温度假说的证据。虽然之前对南极 pycnogonids 的种间研究发现，体型较大的动物具有更多多孔的角质层，因此可能通过增加氧气扩散率来抵消它们更高的有氧代谢需求，但这两种温带物种的角质层的孔隙面积并未随体型变化而变化。这表明温水海蜘蛛的体型通常较小，可能是由于氧气限制以外的选择性因素造成的。