Fig. 1.

Xenoturbella morphology and collections. a External morphology of Xenoturbella bocki. Side furrows (black arrow) are present on the lateral sides from the anterior tip (a), but these do not reach the posterior end (p). The mouth (black arrowhead) is situated on the ventral side anterior to the circumferential furrow (white arrowhead). Scale bar: 1 cm. b Xenoturbella is collected at Gullmarsfjord, Sweden, using a Warén’s dredge and the research vessel Oscar von Sydow, Sven Lovén Centre- Kristineberg, Gothenburg University. Mud is brought up from the sea bottom with the dredge, and is sieved to search for the animal. c Statocyst of an animal pressed between cover and slide glasses. Round cells are observed within the organ. Scale bar: 50 μm