Invertebrate Department

Reproduction

 

The reproductional cycle in L. maerski is only scarcely known. Even though the type locality on Disko Island has been sampled every summer since 1994 and the collected animals afterwards have been cultured in the laboratory, only specimens with female organs have been recorded. Based on this it has been concluded that L. maerski most of the time reproduce by parthenogenesis, which means that the females produce offspring without initial fertilization from a male. In other words, the maternal individuals are able to clone themselves.

However, there are indices that males could be present in a short period. We know that L. maerski is capable of producing two kinds of eggs. A thick-shelled, ornamented type (see the pictures) and a more thin-shelled, smooth type. The thin-shelled type is a summer egg that quickly will hatch, whereas the thick-shelled type probably is a winter egg that are able to withstand freezing in the cold season. A similar reproductional cycle, with two kinds of eggs, is known from the group Rotifera (wheel animals) and in this group we know that the thick-shelled eggs only are produced after male fertilization. Hence, it has been proposed that L. maerski, like rotifers, is dioecious but only with males in a very short period.

However, this theory was recently revised. The newest investigations have shown that very young individuals might have male organs, thus we now believe that L. maerski is a protandrous hermaphrodite, which means that the individuals hatch as males and then become females when they grow older.

 

 

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Last update: 30 maj 2007

 

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