. The Biological bulletin. Biology; Zoology; Marine biology. 212 KOMATSU ET Figure 11. Skeletal plates of juvenile specimens of Astcrina minor, treated with KOII. A) Oral skeletal plates in one arm in the specimen shown in Figure 9. a, ambulacral plate; ad, adambulacral plate; im, inferomarginal plate; o, oral plate; os, oral spine; vl, ventro-lateral plate. Scale = 200 ,um. B) Aboral skeletal plates of a specimen having seven pairs of tube- feet in each arm, hatched portions show papular area, m, interradial plate with a rudiment of madreporite. Scale = 450 /xm. C) Skeletal plates in the
. The Biological bulletin. Biology; Zoology; Marine biology. 212 KOMATSU ET Figure 11. Skeletal plates of juvenile specimens of Astcrina minor, treated with KOII. A) Oral skeletal plates in one arm in the specimen shown in Figure 9. a, ambulacral plate; ad, adambulacral plate; im, inferomarginal plate; o, oral plate; os, oral spine; vl, ventro-lateral plate. Scale = 200 ,um. B) Aboral skeletal plates of a specimen having seven pairs of tube- feet in each arm, hatched portions show papular area, m, interradial plate with a rudiment of madreporite. Scale = 450 /xm. C) Skeletal plates in the oral side of one arm in the specimen shown in Figure B. ad, adambulacral plate; im, inferomarginal plate; o, oral plate; vl, ventro-lateral plate. Scale 500 = /im. Discussion A. minor lacks the bipinnaria stage and develops without pelagic life as known in A. gibbosa and A. exigna (Ludwig, 1882; MacBride, 1896; Mortensen, 1921). In general, asteroids whose development is direct have pear-shaped brachiolaria with three brachiolar arms. In species belonging to Astcrina, the brachiolar arms of A. batheri and A. coronata japonica are short and blunt (Komatsu, 1975; Kano and Komatsu, 1978). The brachiolariae of these species have pelagic life. On the other hand, the brachiolar arms of A. minor are well developed and resemble those of A. gibbosa and A. , and yet these brachiolariae spend benthonic life creeping on the substratum before metamorphosis. It is likely, therefore, that well-developed brachiolar arms are one of the adaptive characters of the benthonic Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-; Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass.
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