. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ACTINULAR BEHAVIOR AND NEMATOCYTES 265. Figure 7. Atrichous isorhiza (AD nematocytes discharged from the aboral tentacle tips during nematocyte- printing behavior. (A and B) Nomarski micrographs: many AIs (arrows) were discharged from the tentacle tip. resulting in "printing" around the settlement site. (C) Scanning electron micrograph: different phases from AI nematocyst discharge (1) to nematocyte exclusion (4) from the epithelial tissues of the tentacle tip (at about same phase as in A). (Dl AI nematocytes print
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ACTINULAR BEHAVIOR AND NEMATOCYTES 265. Figure 7. Atrichous isorhiza (AD nematocytes discharged from the aboral tentacle tips during nematocyte- printing behavior. (A and B) Nomarski micrographs: many AIs (arrows) were discharged from the tentacle tip. resulting in "printing" around the settlement site. (C) Scanning electron micrograph: different phases from AI nematocyst discharge (1) to nematocyte exclusion (4) from the epithelial tissues of the tentacle tip (at about same phase as in A). (Dl AI nematocytes printed on glass surface, nc = nematocyst capsule, nf = nematocyte filament, nt = nematocyst tubule. A and B are same magnification. Bar = 50 (A, B) and 10 jiim (Dl. was followed by temporary attachment and larval settle- ment. In contrast, when the tentacle tips of the juvenile polyps were cut off, regeneration and deployment of Ss occurred in the aboral tentacles. Discussion Seasonal variation of colonies and liberation of actinulae Field observations showed that both asexual and sexual reproduction of Tubularia mesembryanthemum continue in a wide range of water temperatures (surface water temper- atures ranged from 12 to 26 °C) from October to July in the vicinity of Nagai coast. Supplies of larvae seemed to be most abundant in the range from 18 to 22 °C. Mature colonies were most dense from June to July, and appeared to degenerate within 1 or 2 months on certain substrata. Colonies appeared from late September to October, possibly regenerating from the once-degenerated stolons. Frequent appearance of colonies on the shadowed surfaces of artifi- cial substrata outside the harbor suggests the importance of certain kinds of microbial films and of water currents in actinulur settlement followed by colony growth. Defining the reproductive cycle of T. mesembryanthemum, which is beyond the scope of this paper, would require tracking the progression of individual colonies, as Hug
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
