Neue Kantonsschule Aarau, Biology Department, Electron Microscopy Unit, Schanzmättelistr. 32, CH-5000 Aarau, Switzerland.
Arthropod Struct Dev. 2013 May;42(3):209-17. doi: 10.1016/j.asd.2013.02.005. Epub 2013 Mar 7.
Several studies on tarantulas have claimed that their tarsi could secrete fine silk threads which would provide additional safety lines for maintaining a secure foot-hold on smooth vertical surfaces. This interpretation was seriously questioned by behavioral experiments, and more recently morphological evidence indicated that the alleged spigots ("ribbed hairs") were not secretory but most likely sensory hairs (chemoreceptors). However, since fine structural studies were lacking, the sensory nature was not proven convincingly. By using transmission electron microscopy we here present clear evidence that these "ribbed hairs" contain many dendrites inside the hair lumen - as is the case in the well-known contact chemoreceptors of spiders and insects. For comparison, we also studied the fine structure of regular silk spigots on the spinnerets and found them distinctly different from sensory hairs. Finally, histological studies of a tarantula tarsus did not reveal any silk glands, which, by contrast, are easily found within the spinnerets. In conclusion, the alleged presence of silk spigots on tarantula feet is refuted.
有几项关于狼蛛的研究声称，它们的跗节可以分泌细丝线，为在光滑的垂直表面上保持稳固的立足点提供额外的安全线。这种解释受到了行为实验的严重质疑，最近的形态学证据表明，所谓的喷口（“有肋毛发”）不是分泌性的，而很可能是感觉性毛发（化学感受器）。然而，由于缺乏精细结构研究，感觉性并没有得到令人信服的证明。通过使用透射电子显微镜，我们在这里提供了明确的证据，证明这些“有肋毛发”在毛腔内部含有许多树突——就像蜘蛛和昆虫中著名的接触化学感受器一样。作为比较，我们还研究了纺器上的常规丝喷口的精细结构，发现它们与感觉毛明显不同。最后，对狼蛛跗骨的组织学研究没有发现任何丝腺，而丝腺在纺器内很容易找到。总之，狼蛛足部存在丝喷口的说法被否定了。
