Chemosensitive hairs in spiders
01 Nov 1970-Journal of Morphology (Wiley Subscription Services, Inc., A Wiley Company)-Vol. 132, Iss: 3, pp 313-333
TL;DR: Multiple innervation and an open tip give strong evidence for a chemoreceptive function in spiders, and from their position and distribution on the distal leg parts, a contact chemoreception is tentatively proposed.
Abstract: Spiders possess curved, blunt-tipped hairs on all legs and palps, which differ in many details from the straight, sharp-pointed, tactile hairs: (1) the blunt tip is open to the outside, which can be demonstrated by high resolution microscopy and by the penetration of dyes; (2) the hair shaft has a double lumen which consists of a circular (tube) and a crescent shaped lumen; (3) this hair is innervated by two to three bipolar neurons whose dendrites enter the small tube, where they arborize into 16–20 branches. Multiple innervation and an open tip give strong evidence for a chemoreceptive function. Concluding from their position and distribution on the distal leg parts, a contact chemoreception is tentatively proposed. This interpretation is supported by the close structural analogy to the known contact chemoreceptors in insects. Observation of behavior indicates the importance of a contact chemoreceptor on spider legs. Other possible chemoreceptors in spiders which have been described previously by other authors are discussed.
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TL;DR: In insects, chemo-, thermo-, and hygroreceptive sensory cells are located exclusively in sensilla, which are organelles built up by a definite number of characteristic cells.
Abstract: Publisher Summary Chemo-, thermo-, and hygroreceptors are primary sensory cells, which bear one or several modified cilia whose membranes are specialized to take part in the transduction process. These membranes must be exposed to the stimuli but also be protected against desiccation, mechanical, and other injury. Hence, a variety of structural specializations is found that serves these functions. In insects, chemo-, thermo-, and hygroreceptive sensory cells are located exclusively in sensilla, which are organelles built up by a definite number of characteristic cells. During development, the innermost enveloping cell produces a cuticular sheath (scolopale), which envelops the dendritic processes for varying distances along their course through the receptor lymph cavity. This sheath producing cell is surrounded by the trichogen cell, which is itself surrounded by the trichogen cell. These cells build up shaft and socket, respectively, of the cuticular outer structures during development. The perikarya of all cells of the sensillum are enclosed within the epidermis.
651 citations
TL;DR: The comparative study of the phylogeny of social behavior in both families uncovers remarkable convergences of patterns from asocial to permanent-social via periodical-social species of spiders.
Abstract: Whereas most spiders are asocial, species in eight families are known to live all their life in communities and are thus “permanent-social.” Their special attributes are: tolerance, interattraction, and cooperation. These peculiarities must have been achieved step by step several times independently. Periodic-social spiders have been studied as a link between asocial and permanent-social spiders. In two families—the cribellate Eresidae and ecribellate Theridiidae—different steps of periodic sociality have been discovered, from brood-care to feeding by regurgitation. The comparative study of the phylogeny of social behavior in both families uncovers remarkable convergences of patterns from asocial to permanent-social via periodical-social species of spiders.
213 citations
TL;DR: A phylogenetic analysis of the two-clawed spiders grouped in Dionycha is presented, with 166 representative species of 49 araneomorph families, scored for 393 characters documented through standardized imaging protocols, and a revision of the main morphological character systems.
Abstract: A phylogenetic analysis of the two-clawed spiders grouped in Dionycha is presented, with 166 representative species of 49 araneomorph families, scored for 393 characters documented through standardized imaging protocols. The study includes 44 outgroup representatives of the main clades of Araneomorphae, and a revision of the main morphological character systems. Novel terminology is proposed for stereotyped structures on the chelicerae, and the main types of setae and silk spigots are reviewed, summarizing their characteristics. Clear homologs of posterior book lungs are described for early instars of Filistatidae, and a novel type of respiratory structure, the epigastric median tracheae, is described for some terminals probably related with Anyphaenidae or Eutichuridae. A new type of crypsis mechanism is described for a clade of thomisids, which in addition to retaining soil particles, grow fungi on their cuticle. Generalized patterns of cheliceral setae and macrosetae are proposed as synapomorp...
208 citations
TL;DR: Fishing spiders (Pisauridae) frequent the surfaces of ponds and streams and thereby expose themselves to predation by a variety of aquatic and semi-aquatic vertebrates, and responded to mock-attacks just as they had to attacks by live frogs.
Abstract: Fishing spiders (Pisauridae) frequent the surfaces of ponds and streams and thereby expose themselves to predation by a variety of aquatic and semi-aquatic vertebrates. To assess the possibility that the impressive jumps of fishing spiders from the water surface function in evading attacks by frogs, attacks by bullfrogs (Rana catesbiana) and green frogs (R. clamitans) on Dolomedes triton were studied. Both the attack dynamics of the frogs and the evasive behaviors of the spiders were recorded at 250 frames per second. A freeze-dried bullfrog, propelled toward spiders with acceleration, posture, and position that approximated the natural attack posture and dynamics, was used to assess the spiders' behavior. Qualitatively, the spiders responded to these mock-attacks just as they had to attacks by live frogs: jumping (N=29 jumps, 56.9% of instances), rearing the legs nearest the attacking frog (N=15, 29.4%), or showing no visible response (N=7, 13.7%). Spiders that jumped always did so away (in the vertical plane) from the attack (mean =137 degrees vs. vertical at 90 degrees or horizontally toward the frog at 0 degrees ). The involvement of the trichobothria (leg hairs sensitive to air movements), and the eyes as sensory mediators of the evasion response was assessed. Spiders with deactivated trichobothria were significantly impaired relative to intact and sham-deactivated spiders, and relative to spiders in total darkness. Thus, functional trichobothria, unlike the eyes, are both necessary and sufficient mediators of the evasion response. Measurements of air flow during frog attacks suggest that an exponential rise in flow velocity is the airborne signature of an attack.
163 citations
References
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TL;DR: A postfixation in osmium tetroxide, even after long periods of storage, developed an image that—notable in the case of glutaraldehyde—was largely indistinguishable from that of tissues fixed under optimal conditions with osmia tetroxides alone.
Abstract: The aldehydes introduced in this paper and the more appropriate concentrations for their general use as fixatives are: 4 to 6.5 per cent glutaraldehyde, 4 per cent glyoxal, 12.5 per cent hydroxyadipaldehyde, 10 per cent crotonaldehyde, 5 per cent pyruvic aldehyde, 10 per cent acetaldehyde, and 5 per cent methacrolein. These were prepared as cacodylate- or phosphate-buffered solutions (0.1 to 0.2 M, pH 6.5 to 7.6) that, with the exception of glutaraldehyde, contained sucrose (0.22 to 0.55 M). After fixation of from 0.5 hour to 24 hours, the blocks were stored in cold (4°C) buffer (0.1 M) plus sucrose (0.22 M). This material was used for enzyme histochemistry, for electron microscopy (both with and without a second fixation with 1 or 2 per cent osmium tetroxide) after Epon embedding, and for the combination of the two techniques. After fixation in aldehyde, membranous differentiations of the cell were not apparent and the nuclear structure differed from that commonly observed with osmium tetroxide. A postfixation in osmium tetroxide, even after long periods of storage, developed an image that—notable in the case of glutaraldehyde—was largely indistinguishable from that of tissues fixed under optimal conditions with osmium tetroxide alone. Aliesterase, acetylcholinesterase, alkaline phosphatase, acid phosphatase, 5-nucleotidase, adenosine triphosphatase, and DPNH and TPNH diaphorase activities were demonstrable histochemically after most of the fixatives. Cytochrome oxidase, succinic dehydrogenase, and glucose-6-phosphatase were retained after hydroxyaldipaldehyde and, to a lesser extent, after glyoxal fixation. The final product of the activity of several of the above-mentioned enzymes was localized in relation to the fine structure. For this purpose the double fixation procedure was used, selecting in each case the appropriate aldehyde.
3,914 citations
TL;DR: More rapid than previous techniques, this method gives blocks which do not fracture unduly on trimming and provides sections of soft tissues at 1 μ for phase contrast microscopy, as well as ultrathin sections which cut as easily with glass knives as sections of methacrylate.
Abstract: Fixed tissue is dehydrated with tertiary butyl alcohol overnight. The following day it is cleared in toluene, infiltrated and embedded in Araldite resin-hardener-accelerator mixture without dibutyl...
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