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Interstitial annelids in the family Saccocirridae live in the extremely turbulent and dynamic swash zone of exposed sandy beaches. We examine herein the relationship between distribution patterns of Saccocirrus pussicus du Bois-Reymond Marcus 1948 and morphodynamics, hydrodynamic zones, and environmental variables at beaches sampled along the Brazilian Atlantic coast. The occurrence and the abundance of S. pussicus at regional scale were positively correlated with the presence of a steep slope, large waves and coarse sand, which are characteristic of reflective beaches. On a local scale, S. pussicus occurred at the swash zone and breaking surf zone of reflective beaches. On a microscale, it preferred the upper 20 cm of the swash zone sediment. Saccocirrus pussicus prefers hydrodynamic zones, which change temporally, suggesting dependence with the dynamics of the surging and plunging waves. The coupling of morphological and behavioral adaptations of S. pussicus to beach morphodynamics is crucial for understanding its surfing life strategies within turbulent environments. [ABSTRACT FROM AUTHOR]

After the deployment of several whale carcasses in Monterey Bay, California, a time-series analysis revealed the presence of a new species of Osedax, a genus of bone-eating siboglinid annelids. That species is described here as Osedax roseus n. sp. It is the fifth species described since the erection of this genus and, like its congeners, uses a ramifying network of "roots" to house symbiotic bacteria. In less than 2 months, Osedax roseus n. sp. colonized the exposed bones of a whale carcass deposited at 1018-m depth, and many of the females were fecund in about 3 months post-deployment. As with other Osedax spp., the females have dwarf males in their tube lumens. The males accrue over time until the sex ratio is markedly male-biased. This pattern of initial female settlement followed by gradual male accumulation is consistent with the hypothesis that male sex may be environmentally determined in Osedax. Of the previously described species in this genus, Osedax roseus n. sp. is most similar to O. rubiplumus, but it has several anatomical differences, as well as much smaller females, dwarf males, and eggs. Osedax roseus n. sp. is markedly divergent (minimally 16.6%) for mitochondrial cytochrome oxidase subunit I (mtCOI) sequences from any other Osedax species. [ABSTRACT FROM AUTHOR]