. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. LUMINESCENCE IN H1PPOPODWS 475 Nutrients are conveyed to them by a canal from the stem which splits into branches upon entering the subumbrella. One of these, the ventral canal, is the site of an epithelial gland, the rete mirabilis or rete. Nectophores can swim using their circular, striated muscle, or roll up the margin (involution), using the radial system of smooth muscle fibers. Marginal nerve rings are present as in hydromedusae, but there is no general nerve plexus over the sub- or ex-umbrella and there are no nervous
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. LUMINESCENCE IN H1PPOPODWS 475 Nutrients are conveyed to them by a canal from the stem which splits into branches upon entering the subumbrella. One of these, the ventral canal, is the site of an epithelial gland, the rete mirabilis or rete. Nectophores can swim using their circular, striated muscle, or roll up the margin (involution), using the radial system of smooth muscle fibers. Marginal nerve rings are present as in hydromedusae, but there is no general nerve plexus over the sub- or ex-umbrella and there are no nervous connections between the marginal nerve centers of the different nectophores in the colony ( Mackie, 1965). Considered as a medusoid, the nectophore is highly asymmetrical compared with free medusae (Figs. 1, 2, 14). The mesogloea is concentrated dorsally, while the subumbrella cavity is displaced ventrally. The outer or dorsal surface is a convex dome, the inner, ventral side being more concave. These features allow the nectophores to fit together into an interlocking structure with smooth sides and with the swimming jets directed backward. The exumbrella surface is generally. sub FIGURE 2. Internal morphology (after Chun, 1897). The "axis" of the colony is defined by the stem(s) which hangs in a central space surrounded by nectophores. Branched stem processes join the nectophores together, attaching to their axial surfaces. "Top" and "bottom"' refer to aspects of the colony seen in its normal orientation, as shown here. "Dorsal" and "ventral" poles of the nectophore are indicated for the bottom nectophore on the left (d, v) ; the exumbrellar surface (ex) is the entire outer surface of the nectophore; the subumbrellar cavity (sub) is the inner chamber whose muscular walls produce the locomotory water jet. Other symbols : mes = mesogloea ; pv = pseudovelum : vel = velum. Scale is 1 Please note that these images are extracte
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
