Mjf. Blumer et al., OCELLI IN A CNIDARIA POLYP - THE ULTRASTRUCTURE OF THE PIGMENT SPOTS IN STYLOCORONELLA-RIEDLI (SCYPHOZOA, STAUROMEDUSAE), Zoomorphology, 115(4), 1995, pp. 221-227
Within the Cnidaria, the occurrence of oceili at the polyp stage is on
ly known in the species of Stylocoronella (Scyphozoa, Stauromedusae).
The light-sensitive organs of S, riedli are ultrastructurally investig
ated. In this interstitial-living species, each of the up to 24 ocelli
is composed of between seven and nine monociliary sensory cells and b
etween one and four pigment cells. A striking feature of the photorece
ptive cilia is their peculiar axonemal pattern. This is expressed (a)
by the presence of a third central microtubule at a certain point and
(b) by the balloon-like swelling of the distal portion of the cilium,
with clearly scattered microtubules in this area. Although the polyps
of S. riedli show no distinct reaction to light stimuli, the ultrastru
ctural results corroborate the hypothesis that these organs are light-
sensitive organs. The possible function of the pigment granules is dis
cussed.