Fig. 3

S. alveolata. Tentacular filaments. a-d SEMs, e-h Anti-acetylated α-tubulin-like immuno-reactivity, cLSM z-stacks, a Tentacular filaments (tf) situated ventrally on the operculum, b Tentacular filament carrying a strong ciliary band (cb) on the frontal side (fs) and a few groups of cilia (boxed) on the abfrontal side (afs), c Enlargement of boxed ciliary group from b presumably belonging to receptor cells, d Tentacular filament with short transverse rows of long cilia (arrows) regularly arranged on each side of the frontal ciliary band (cb), e Lateral view of filament, strong ciliary band (cb) and groups of long cilia, tufts of sensory cilia (sc) on the abfrontal side, f Two nerves (n) running along abfrontal side of tentacular filament, frontal view, selected z-stack projection to eliminate the strong signal of the ciliary band, g Tip of filament with groups of sensory cilia on the very top (arrow), abfrontal nerves (n) branch and their processes giving rise to sensory cilia, h Enlargement of the middle part of a tentacular filament, lateral view, each sensory ciliary bundle (sc) connected via a single neurite to the ventrally running nerves, from the same nerve neurites approach transverse groups of long cilia. Abbreviations: afs - abfrontal side, cb - ciliary band, cg - group of long cilia, fs - frontal side, mo - mouth, n - nerve, neu - neuropodium, not - notopodium, op - opercular papilla, pa - opercular palaea, sc - sensory cilium, tf - tentacular filament