Semi-aquatic spider silks: transcripts, proteins, and silk fibres of the fishing spider, Dolomedes triton (Pisauridae).

To survive in terrestrial and aquatic environments, spiders often rely heavily on their silk. The vast majority of silks that have been studied are from orb-web or cob-web weaving species, leaving the silks of water-associated spiders largely undescribed. We characterize transcripts, proteins, and silk fibres from the semi-aquatic spider Dolomedes triton. From silk gland RNAseq libraries, we report 18 silk transcripts representing four categories of known silk protein types: aciniform, ampullate, pyriform, and tubuliform. Proteomic and structural analyses (scanning electron microscopy, energy dispersive X-ray spectrometry, contact angle) of the D. triton submersible egg sac reveal similarities to silks from aquatic caddisfly larvae. We identified two layers in D. triton egg sacs, notably a highly hydrophobic outer layer with a different elemental composition compared to egg sacs of terrestrial spiders. These features may provide D. triton egg sacs with their water repellent properties.

Spatial and Seasonal Changes in Microbial Community of Hynobius amjiensis Breeding Pools in a Sphagnum-Dominated Peatland.

Peatlands deliver a variety of beneficial ecosystem services, particularly serving as habitats for a diverse array of species. Hynobius amjiensis is a critically endangered amphibian initially discovered in a Sphagnum-dominated peatland in Anji, China. The unique habitat requirements of H. amjiensis make it highly vulnerable to environmental changes. Here, we investigated the different breeding pools of H. amjiensis in the Sphagnum-dominated peatland (the type locality) for a one-year period to evaluate the interactions among the egg sacs present, water quality, and microbial communities (16S and 18S rRNA gene amplicon). The numbers of egg sacs were higher in the breeding pools located at the marginal area than those at the core area of the peatland. Similarly, the α-diversity of bacteria, fungi, and protists were lower in the core region compared to those at the edge of the peatland, perhaps due to water eutrophication. The microbial communities and water quality differed significantly among breeding pools and sampling months. The simpler microbial networks of the breeding pools in the core wetland may impact the numbers and health of the egg sacs. This study contributes to a better understanding of the effect of water quality on biodiversity in peatlands, and it can also guide regulations for wetland conservation and the protection of endangered species.

An arboreal spider protects its offspring by diving into the water of tank bromeliads.

Cupiennius salei (Ctenidae) individuals frequently live in association with tank bromeliads, including Aechmea bracteata, in Quintana Roo (Mexico). Whereas C. salei females without egg sacs hunt over their entire host plant, females carrying egg sacs settle above the A. bracteata reservoirs they have partially sealed with silk. There they avoid predators that use sight to detect their prey, as is known for many bird species. Furthermore, if a danger is more acute, these females dive with their egg sacs into the bromeliad reservoir. An experiment showed that this is not the case for males or females without egg sacs. In addition to the likely abundance of prey found therein, the potential of diving into the tank to protect offspring may explain the close association of this spider with bromeliads. These results show that, although arboreal, C. salei evolved a protective behavior using the water of tank bromeliads to protect offspring.