Measurements of isolated statocysts
in slices prepared in the sagittal plane (n = 11) or in the tentacular plane (n = 9) show that the mean statolith displacement from the midline at 90[degrees] is similar to that at 270[degrees] in either body plane.
appear in the proximal region of the antennular peduncle from stage VII onward.
sinuosa On proximal Linear, 4 Lin, Xu, Huang portion of longitudinally & Wang, 2009 manubrium divided Species Number of Number of Number of Number of statocysts
marginal marginal cirri vesicles bulbs L.
Eyes absent, no nuchal organs, no so-called statocysts
dorso-anteriorly; salivary glands inconspicuous; thick, double-circular band of cilia around mouth, which continues as a ventral ciliary band to the last segment, male paired, separated lateral organs in segments 6-11.
Aboral observations of statocysts
in Mnemiopsis of various sizes show no consistent spatial pattern of release of lithocytes with respect to individual balancers.
The fixed statocysts
were then rinsed three times for 5 min in PBS (0.1 mol [l.sup.-1] phosphate buffered saline; Sigma Aldrich, St.
Scyphozoans, unlike several hydrozoan medusae, do not have true statocysts
. The terminal end of each rhopalium contains a statolith, but it is covered with a tightly adhering epithelium.
As both phototactic and geotactic behaviors are commonly reported for cercariae (Fingerut et al, 2003b; reviewed in Sukhdeo and Sukhdeo, 2004), subsequent ultrastructural studies on photoreceptors and statocysts
, and neural mechanisms for their integration, are warranted.
2C), where it passed between the two statocysts
and beneath the cerebral commissure of the nervous system.
By day 3, the foot, velum, and shell had each enlarged, and additional features included statocysts
, lightly pigmented eyes, and a small operculum.
The sensory structures stimulated by the US are the two central gravity-detecting statocysts
(Alkon and Bak, 1973; Detwiler and Alkon, 1973; Detwiler and Fuortes, 1973; Alkon, 1975).
In some cases, systems emerged that are unique to modern cephalopods (e.g., the chromatophore system; for review see Packard et al., 1988; Demski, 1992), while other systems evolved analogous in structure and function to those of vertebrates (e.g., camera eyes and statocysts
; see also Hochner, 2004).