. The biology of marine animals. Marine animals; Physiology, Comparative. EFFECTOR MECHANISMS 373 filament which in some species reaches a length fifty times that of the spore (Fig. ). Exposure to the digestive fluids of the host causes the contained thread to unroll and shoot out. The discharged threads serve temporarily to anchor the parasite to the gut wall of the host (27, 30, 49, 56, 59, 101). Nematocysts and Colloblasts Nematocysts or stinging cells are found in coelenterates. Colloblasts or adhesive cells occur in ctenophores. The nematocysts of coelenterates are small capsules lying
. The biology of marine animals. Marine animals; Physiology, Comparative. EFFECTOR MECHANISMS 373 filament which in some species reaches a length fifty times that of the spore (Fig. ). Exposure to the digestive fluids of the host causes the contained thread to unroll and shoot out. The discharged threads serve temporarily to anchor the parasite to the gut wall of the host (27, 30, 49, 56, 59, 101). Nematocysts and Colloblasts Nematocysts or stinging cells are found in coelenterates. Colloblasts or adhesive cells occur in ctenophores. The nematocysts of coelenterates are small capsules lying in cells known as nematocytes or cnidoblasts. The capsules are minute structures, usually. Fig. Nematocysts (Holotrichous Isorhizas) of Corynactis a, capsule and base of shaft after discharge (fresh smear in distilled water), b, nemato- cyst before discharge (dried smear in distilled water), c, shaft of an incompletely dis- charged nematocyst, showing the tip; a-d, focused in different planes (dried smear in distilled water). (From Robson (107).) some 5-50 jli in length, and fusiform to spherical in shape. Within the capsule lies coiled a hollow thread which can be everted (Fig. ). An operculum caps the nematocyst and there is often a bristle-like cnidocil on the outer surface of the cell. Other structures frequently present are supporting rods about the periphery of the cnidoblast, and a fibrillar network associated with the capsule. There are two main types of nematocysts; the spirocysts of Zoantharia, and nematocysts proper found in all groups of coelenterates. The spiro- cysts have thin-walled capsules permeable to water, and they discharge unarmed adhesive threads. The nematocysts proper comprise a large variety of forms, distinguishable by characters of their discharged threads. All of them have thick-walled capsules impermeable to water except at discharge, and containing threads that are usually armed with spines. Please note that these images are extracted fro
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Keywords: ., bookcentury1900, booksubjectmarineanimals, booksubjectphysiology
