Fig. 2

Images of Oligobrachia worms and the focus of this study. A: In situ image of tufts of Oligobrachia worms (image courtesy of the Arctic SGD project). The black hair like extrusions from the sediment surface are the anterior ends of the worms within their brown-black tubes. B: The anterior part and tentacles of an Oligobrachia sp. CPL-clade worm within its tube. In this part, the tube is translucent and the animal within is visible. Note the pointed head/frenulum (bottom arrow) and the red tentacles extending from it (top arrow). C: Anterior of an Oligobrachia sp. CPL-clade worm after extraction from its tube, showing several red tentacles attached anteriorly to the pointed frenulum (arrow). D: The opisthosome (posterior most end) of an Oligobrachia sp. CPL-clade worm extracted from its tube, showing its segmentation (arrow). E: Larvae within the tube of an individual worm (upwards pointing bottom arrows). These were present in the transparent, anterior end of the tube, anterior to the worm and its tentacles. On the outside of the tube, note the presence of white, filamentous bacteria (slanted top arrows)