Cryptic frenulates are the dominant chemosymbiotrophic fauna at Arctic and high latitude Atlantic cold seeps
Fig 5
Morphology of the pingo-crater worms and O. haakonmosbiensis.
A: Live profile view of one of the pingo and crater worms (individual #1078–1 from the pingo site). The different body parts are shown (most of the trophosome and the opisthosome are missing). The head is anterior to the frenulum. The forepart is anterior to the diaphragm. The pre-annular trunk is anteriorly limited by the diaphragm, and posteriorly by the two girdles. The post-annular trunk starts with a narrowing behind the girdles and posteriorly contains the black trophosome. B: Close up view of the head and forepart of O. haakonmosbiensis (Storegga) showing the bridle keels of the frenulum. C: Close up view of the head and forepart of a pingo-crater worm (individual # 1125–7 from the crater site) showing the bridle keels of the frenulum.