Fig. 1

Osedax japonicus general and chaetal morphology. a Adult female Osedax japonicus with four elongate palps (pa) and root tissue (ro) dissected out of the bone. b Mature dwarf male with vital sperm (sp) within the body cavity. The position of posteriorly located chaetae are marked with arrowheads. c 5-day old competent trochophora larva, with 3 rows of ciliary bands in the prototroch (pt) and a single ciliary band in the posterior telotroch (tt). d Scanning electron microscopic (SEM) image of the posterior end of a late larva with hooked shaped chaetae (ch), arranged in pairs e SEM showing detail of the hooked chaetae, each with ca. 10 teeth (te). f Schematic drawing of a chaetal follicle with three follicle cells (fc) and the basal most chaetoblast (cb) with an apical array of dynamic microvilli. Abbreviations: cb chaetoblast, ch chaetae, fc follicle cell, pa palps, pt prototroch, ro root tissue, sp sperm, te teeth, tt telotroch. Scale bars: a 2 mm, b 50 µm, c 25 µm, d 10 µm, and e 2 µm