Publication Date:
2020-07-16
Description:
Precocious maturation of male and female I. illecebrosus , induced in the laboratory in about 50 days, was followed by mating and spawning and yielded jelly-like egg masses up to 1 m in diameter containing 100,000 eggs. Fully mature males contained several hundred spermatophores, generally more than were implanted in the mantle of a female. The jelly released by the nidamental glands appears to trigger sperm release from implanted spermatophores. More than one egg mass was produced by single females and eggs remained in the ovary when the females died after spawning. The egg masses were neutrally buoyant and tended to drift with the weak current present in the pool. Larvae hatched in 6-7 days after spawning at about 13 C with mantle length of 1.1 mm. Eight days after hatching (maximum survival time), they had a mantle length of 1.25 mm and were similar to, but younger than, specimens found in plankton collections in late winter. All stages in the life cycle of I. illecebrosus have now been characterized, and the available information is consistent with the hypothesis of a 1-year life cycle with spawning possibly occurring in February. Major gaps in knowledge at present are the spawning time and location. Identification of egg masses and larvae may be useful in determining the time of spawning but the capture of mated females may be the best indicator of spawning sites.
Type:
Article
,
PeerReviewed
Format:
text
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