Dangerous mating systems: signal complexity, signal content and neural capacity in spiders.

Spiders are highly efficient predators in possession of exquisite sensory capacities for ambushing prey, combined with machinery for launching rapid and determined attacks. As a consequence, any sexually motivated approach carries a risk of ending up as prey rather than as a mate. Sexual selection has shaped courtship to effectively communicate the presence, identity, motivation and/or quality of potential mates, which help ameliorate these risks. Spiders communicate this information via several sensory channels, including mechanical (e.g. vibrational), visual and/or chemical, with examples of multimodal signalling beginning to emerge in the literature. The diverse environments that spiders inhabit have further shaped courtship content and form. While our understanding of spider neurobiology remains in its infancy, recent studies are highlighting the unique and considerable capacities of spiders to process and respond to complex sexual signals. As a result, the dangerous mating systems of spiders are providing important insights into how ecology shapes the evolution of communication systems, with future work offering the potential to link this complex communication with its neural processes.

Surviving the flood: plastron respiration in the non-tracheate arthropod Phrynus marginemaculatus (Amblypygi: Arachnida).

Specimens of Phrynus marginemaculatus can remain responsive when submerged in water for more than 24 hours. Behavioral data indicate that P. marginemaculatus utilizes dissolved oxygen from the surrounding water. Scanning electron miscroscopy and light microscope sections show cuticular modifications for plastron respiration. All previous examples of plastron respiration have involved animals with tracheal systems, but amblypygids respire through the use of two pairs of book lungs. This study provides the first example of plastron respiration not only in the order Amblypygi, but also, in any non-tracheate arthropod.