Contribution to the Knowledge of the Nudibranchiate Mollusk, Melibe Leonina (Gould)

H. P. Von W. Kjerschow-Agersborg
The American Naturalist
Vol. 55, No. 638 (May - Jun., 1921), pp. 222-253
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Page Count: 32
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Contribution to the Knowledge of the Nudibranchiate Mollusk, Melibe Leonina (Gould)


1. Melibe leonina is a large carnivorous Nudibranch reaching sometimes 14 centimeters in total length; it is an actively predaceous animal; it practically gorges itself, feeding mainly on small Crustacea; it is gregarious. 2. It seems to live more than one year; its recurrence is spasmodic. 3. It swims freely in the water, backward, upward or downward; it crawls on the surface by the surface tension, and on sea-weeds, by the help of its highly ciliated foot. 4. Its defensive means are an offensive odor and death feigning. 5. It drops to deeper water by relaxation of its muscles. 6. It collects in groups among sea-weeds, where copulation takes place. 7. Mutual insemination does not seem to be simultaneous. 8. It spawns as early as March and as late as July; sexual maturity is reached quite early, as young ones two centimeters long were found with ripe spermatozoa. 9. Spermatozoa from another individual are stored in the ovo-spermatotheca but wander up the uterus as far as the prostate. 10. Eggs are also stored in the spermatotheca, hence the name ovo-spermatotheca. 11. Copulating individuals are of the same relative size. 12. The same individual deposits more than one nidosome, after insemination; spermatozoa may be carried over in the ovo-spermatotheca at least two weeks. 13. The eggs are deposited in capsules, normally containing from 15 to 22 eggs. The capsules are arranged in rows within a gelatinous mass, sometimes quite regularly; the gelatinous mass is formed into a belt from 3 to 5 cm. wide; the mucous flow is greater in one side of the belt than in the other, so that one side of the belt is shorter than the other, and the belt curves into a funnel-shaped mass, the apex adhering to some sea-weed, near the surface of the water. 14. Eggs may become incapsulated without being fertilized; no cleavage of such eggs follows. 15. Normally the embryo develops within two weeks.