Water Webbing: Long-Jawed Spider (Araneae, Tetragnathidae) Produces Webs That Touch the Surface of Ephemeral Waterbodies

Few spiders are known to construct silk webs that physically contact water, despite it being both a surface and medium that can be exploited for web construction. Herein, we report on an Australian long-jawed spider from the Tetragnatha genus (Tetragnatha cf. nitens) that frequently produces aerial webs that touch the surface of ephemeral waterbodies. Field observations revealed webs that were built by these spiders at varying heights above water in emergent vegetation stands around the edge of ephemeral waterbodies. Approximately, 15 of the 100 webs recorded were constructed immediately above the water with their lower sections making physical contact with the water's surface. We observed water striders becoming stuck within these low-lying webs, suggesting that associating webs with surface water allows the spiders to exploit prey types that cannot be passively filtered from the environment in purely aerial webs. This could suggest that some species of long-jawed spider select the positioning of their webs above water, which would be adaptive if it allows them to target different and possibly multiple prey communities.