Division of Biological Sciences, University of Montana, Missoula, MT, USA.
Division of Biological Sciences, University of Montana, Missoula, MT, USA.
Curr Biol. 2017 Jul 10;27(13):R638-R639. doi: 10.1016/j.cub.2017.05.062.
The fundamental constraint shaping animal systems for internal gas transport is the slow pace of diffusion [1]. In response, most macroscopic animals have evolved systems for driving internal flows using muscular pumps or cilia. In arthropods, aside from terrestrial lineages that exchange gases via tracheal systems, most taxa have a dorsal heart that drives O-carrying hemolymph through peripheral vessels and an open hemocoel [2], with O often bound to respiratory proteins. Here we show that pycnogonids (sea spiders), a basal group of marine arthropods [3], use a previously undescribed mechanism of internal O transport: flows of gut fluids and hemolymph driven by peristaltic contractions of a space-filling system of gut diverticula. This observation fundamentally expands the known range of gas-transport systems in extant arthropods.
塑造动物内部气体运输系统的基本限制因素是扩散的缓慢速度[1]。为了应对这一挑战，大多数大型动物已经进化出了使用肌肉泵或纤毛来驱动内部流动的系统。在节肢动物中，除了通过气管系统进行气体交换的陆生谱系外，大多数类群都有一个背侧心脏，它通过外周血管驱动携带 O 的血淋巴，并具有一个开放的血腔[2]，其中 O 通常与呼吸蛋白结合。在这里，我们展示了 pycnogonids（海蜘蛛），一种海洋节肢动物的基础群体[3]，使用了一种以前未被描述的内部 O 运输机制：由充满肠道憩室的空间填充系统的蠕动收缩驱动的肠道液和血淋巴的流动。这一观察结果从根本上扩大了现存节肢动物中气体运输系统的已知范围。
