Fig. 1.

Morphology of H. hongkongensis (H13), viewed from the upper (a) and lower (b) sides. Note that the animals were fixed, while they were not adhering to a substrate, thereby showing great variability in body shapes, as they can form invaginations, ripples, curls, and can variably stretch and contract. c Ciliated epithelia in H. hongkongensis (H13). The lower surface (le) is more densely ciliated than the upper surface (ue). Scale bar 50 μm in a, b; 8 μm in c