crustacean metagenome Metagenome. crustacean metagenome

Transparent species are nearly invisible when viewed under ambient light in the pelagic zone; however, at shallow depths (where light is more directional and thus more likely to cause reflections), and under the bioluminescent searchlights of potential predators, transparent species may be revealed by reflections from their body [1 - 7]. We investigated the surfaces of transparent hyperiid amphipods using SEM and found two undocumented features that minimize these reflections. We found that the appendages of Cystisoma spp. (n=5) are covered with an ordered array of nanoprotuberances 204 ± 3 nm in height that function optically as a gradient refractive index material [6, 8, 9]. Additionally, in an unexpected discovery, we observed that the dorsal surfaces of Cystisoma spp. (n=5) as well as six other transparent species of hyperiids are covered with a dense biofilm composed of what appear to be homogenous spheres (diameters ranging from 52 ± 1 nm to 317 ± 3 nm). Exposure of artificial seawater to Phronima sp. changed the local microbial biodiversity of the water and identified candidate species. Optical modeling demonstrates that both the nanoprotuberances and the spherical bacteria reduce reflectance of blue-green bioluminescence and ambient light by as much as 100-fold. These findings expand our understanding of anti-reflective structures and of the diversity and possible associations of picobacteria with zooplankton.