The reproductive cycle of Gorgonocephalus caryi (Echinodermata; Ophiuroidea).

Abstract

1. Samples of gonads from Gorgonocephalus caryi collected monthly over a 13-month period were examined histologically to determine the course of the reproductive cycle.2. The reproductive cycle of both sexes was divided into 5 stages: Post-spawning, Early Growth, Resting, Late Growth, and Spawning. The Maturity Index (Yoshida, 1952) was calculated separately for males and females for each month.3. The histology of the ovaries in the various stages is described.4. Maturation divisions in females probably occur on the day of spawning and proceed very much as in the crinoid, Comanthus japonica (Dan, 1952).5. Gorgonocephalus has an annual reproductive cycle and spawns for six months of the year, from June through November in the population studied in 1965-1966. In the winter of 1966-1967, animals collected from a different location spawned in the laboratory from November through March.6. Each animal spawns more than once during the spawning season.7. Gonad development is arrested after the initial stages of gametogenesis have commenced rather than immediately after spawning, as occurs in most other echinoderms.8. The curve for growth of the largest oocytes corresponds well with the female Maturity Index, indicating that oocyte size is a good measure of gonadal maturity.9. The male and female Maturity Indices correspond well, and the differences between them can be explained by differences between oogenesis and spermatogenesis.