Schmitz A, Perry S F
Institut für Zoologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Poppelsdorfer Schloss, 53115 Bonn, Germany.
J Exp Biol. 2001 Dec;204(Pt 24):4321-34. doi: 10.1242/jeb.204.24.4321.
In jumping spiders, both the book lungs and the tracheal system are well-developed. The tracheal system consists of four thick primary tracheae that branch into small secondary tracheae, some of them ending in the opisthosoma and others entering the prosoma. We used stereological morphometric methods to investigate the morphological diffusing capacity of the lungs and of the walls of the secondary tracheae ('lateral diffusing capacity') of two groups of Salticus scenicus with mean body masses of 2.69 mg (group A) and 5.28 mg (group B). The thickness of the gas-exchange epithelium of the lungs was 0.164 microm (group A) and 0.186 microm (group B) for the total diffusion barrier. The secondary tracheae were divided arbitrarily into seven classes according to their inner diameter (1-7 microm). The diffusion barriers of the tracheal walls tend to be thinnest (0.17 and 0.18 microm) for the smallest tracheae, the walls of the other tracheal classes having approximately the same thickness of diffusion barrier (0.24-0.32 microm). The calculated oxygen-diffusing capacity (D(O(2))) for the lungs was 16.4 microl min(-1) g(-1) kPa(-1) for group A and 12 microl min(-1) g(-1) kPa(-1) for group B; the D(O(2)) of the walls of all secondary tracheae was 5.91 microl min(-1) g(-1) kPa(-1) for group A animals and 6.63 microl min(-1) g(-1) kPa(-1) for group B animals. Our results are consistent with the hypothesis that the tracheal system plays an important role in gas exchange in jumping spiders. Resting and low-activity oxygen consumption rates can be met by the lungs or the tracheae alone, while high oxygen demands can be met only if both respiratory systems are working together. Tracheae entering the prosoma have only 4-10 % of the total tracheal diffusing capacity, thus providing sufficient oxygen for the nervous system but not being able to prevent muscle fatigue. The similar thickness of the walls of all tracheal classes is consistent with the hypothesis that the secondary tube tracheae function as 'tracheal lungs', supplying the haemolymph and organs by lateral diffusion.
在跳蛛中，书肺和气管系统都很发达。气管系统由四条粗大的初级气管组成，这些初级气管分支形成细小的次级气管，其中一些次级气管终止于腹部，另一些进入头胸部。我们使用体视学形态计量学方法，研究了两组平均体重分别为2.69毫克（A组）和5.28毫克（B组）的孔雀跳蛛的肺以及次级气管壁的形态扩散能力（“侧向扩散能力”）。肺的气体交换上皮的厚度，对于总扩散屏障而言，A组为0.164微米，B组为0.186微米。次级气管根据其内径（1 - 7微米）被任意分为七类。气管壁的扩散屏障对于最细的气管往往最薄（0.17和0.18微米），其他气管类别的壁具有大致相同厚度的扩散屏障（0.24 - 0.32微米）。计算得出，A组肺的氧扩散能力（D(O₂)）为16.4微升·分钟⁻¹·克⁻¹·千帕⁻¹，B组为12微升·分钟⁻¹·克⁻¹·千帕⁻¹；A组动物所有次级气管壁的D(O₂)为5.91微升·分钟⁻¹·克⁻¹·千帕⁻¹，B组动物为6.63微升·分钟⁻¹·克⁻¹·千帕⁻¹。我们的结果与以下假设一致：气管系统在跳蛛的气体交换中起重要作用。静息和低活动状态下的耗氧率仅靠肺或气管就能满足，而高氧需求只有在两个呼吸系统共同工作时才能满足。进入头胸部的气管仅占气管总扩散能力的4 - 10%，因此能为神经系统提供足够的氧气，但无法防止肌肉疲劳。所有气管类别的壁厚度相似，这与以下假设一致：次级管状气管起到“气管肺”的作用，通过侧向扩散为血淋巴和器官供氧。
