Optimization of cylindrical pressure vessels with respect to weight

Рач, В.А.

doi:10.1007/bf00613116

Cited by 2 publications

(1 citation statement)

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“…The shank itself is adapted so it will not be crushed when the spider walks or collapse during silk extrusion and it can bear the tension of the silken tether anchoring the tarantula tarsus to the glass. The linked, angled annular thickenings, offset across the width of the shank are similar to the reinforcements seen in pressure vessels (Karam, 2005;Wigglesworth, 1965;Rach, 1990) and suggest the spigot's role as a silk delivery and anchoring device. Can we explain why no tarsal silk deposits were found by Pérez-Miles and colleagues (Pérez-Miles et al, 2009) when they blocked the spinnerets of the zebra tarantula and allowed it to roam in a shallow tank?…”

Section: Discussionmentioning

confidence: 54%

Tarantulas cling to smooth vertical surfaces by secreting silk from their feet

Rind

Birkett

Duncan

et al. 2011

Journal of Experimental Biology

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SUMMARYLike all spiders, tarantulas (family Theraphosidae) synthesize silk in specialized glands and extrude it from spinnerets on their abdomen. In one species of large tarantula, Aphonopelma seemanni, it has been suggested that silk can also be secreted from the tarsi but this claim was later refuted. We provide evidence of silk secretion directly from spigots (nozzles) on the tarsi of three distantly related tarantula species: the Chilean rose, Grammostola rosea; the Indian ornamental, Poecilotheria regalis; and the Mexican flame knee, Brachypelma auratum, suggesting tarsal silk secretion is widespread among tarantulas. We demonstrate that multiple strands of silk are produced as a footprint when the spider begins to slip down a smooth vertical surface. The nozzle-like setae on the tarsi responsible for silk deposition have shanks reinforced by cuticular thickenings, which serve to prevent the shanks' internal collapse while still maintaining their flexibility. This is important as the spigots occur on the ventral surface of the tarsus, projecting beyond the finely divided setae of the dry attachment pads. We also reveal the structure and disposition of the silk-secreting spigots on the abdominal spinnerets of the three tarantula species and find they are very similar to those from the earliest known proto-spider spinneret from the Devonian period, giving another indication that silk secretion in tarantulas is close to the ancestral condition.

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Section: Discussionmentioning

confidence: 54%