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The Biological bulletin (20379800335)


The Biological bulletin (20379800335)



Title: The Biological bulletin
Identifier: biologicalbullet204mari (find matches)
Year: [1] (s)
Authors: Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-1983
Subjects: Biology; Zoology; Biology; Marine Biology
Publisher: Woods Hole, Mass. : Marine Biological Laboratory
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

Text Appearing Before Image:
ACTINULAR BEHAVIOR AND NEMATOCYTES 263 of 3-week-old films. Thus, microbial films significantly (P < 0.0001) promoted actinular settlement. These larval responses did not occur without direct contact of the aboral tentacles to the microbial-filmed surface. Three days after liberation, juvenile polyps showed the following characteristics: aboral tentacle length, 600-1300 jum (mean ± standard deviation = 800.8 ± 187.2); oral tentacle length, 73-120 /urn (89.0 ± 17.3); body length, 433-968 /Ltm (660.9 ± 186.6); body width, 130-200 /urn (170.9 ± 23.4). Discharge and printing of the tentacular nematoc\tes during larval settlement Large numbers of atrichous isorhizus (Als) were ob- served at the tips of the aboral tentacles in the pre-attach- ment stage (Fig. 5 A, C). With time following larval liber- ation, the knobs of the aboral tentacle tips gradually became indistinct, and so sticky that repeated pipetting could not tear the tips from the substrata. These changes were accom- panied by the transformation of the knob surfaces (the number of cnidocils decreased and the number of dis- charged tubes increased. Fig. 5B). Temporary attachment was achieved by anchoring with the tubes of the discharged Als to the substrata surface. Observations with the inverted and scanning electron microscopes showed that the settling larvae discharged many AI nematocytes from the aboral tentacle tips in con- cert with their sinuous movement, active rubbing of the tentacles, and body-swaying on the glass surfaces during settlement. As a result, the discharged nematocytes were stuck around the settlement site (Figs. 6. 7). In contrast, temporary attachment was achieved by one or two tubes of the discharged Als from a rigid tentacle; the sinuous tenta- clar behavior and the AI discharge and sticking (more than 50 from a tentacle) were peculiar to larval settlement (Figs. 6. 7) and thus were termed "nematocyte-printing behavior." D\namic chunges in nematoc\te composition during larval settlement Figure 8 shows the changes in nematocyte composition of the aboral tentacles during larval development and behav- ior. No nematocytes were observed in the aboral tentacle rudiments of the star-shaped embryos. The preactinula had only small numbers of atrichous isorhizas (Als) (20.5 ±
Text Appearing After Image:
Figure 5. Scanning electron micrographs of aboral tentacle tip*, of actinula larvae, and Nomarski interfer- ence micrographs of nematocysts in the tentacle tip and body wall. (A) 2-4-h-old larva: (B) 1-day-old larva: (C) atrichous isorhiza nematocysts in the tentacle tip: (D) small stenotele nematocysts in the body wall (2-4-h-old larva). C and D are same magnification. Bar = 5 /am.





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