. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. HERMAPHRODITISM IN ECHINOIDS 329 At Pacific Grove, although the use of sea urchins has gone on for many years, only one bisexual individual each of .S". pnrpitnitus and .S". franciscanus has heen detected. In all these cases the selfed eggs gave normal plutei. In the specimen of .V. pnrpnratns opened at Pacific Grove in December, 1950 (), the gonads were swollen with ripe products and easily broken. There were three ovaries, one testis and one ovotestis. None of the eggs could have been fertilized in corf>
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. HERMAPHRODITISM IN ECHINOIDS 329 At Pacific Grove, although the use of sea urchins has gone on for many years, only one bisexual individual each of .S". pnrpitnitus and .S". franciscanus has heen detected. In all these cases the selfed eggs gave normal plutei. In the specimen of .V. pnrpnratns opened at Pacific Grove in December, 1950 (), the gonads were swollen with ripe products and easily broken. There were three ovaries, one testis and one ovotestis. None of the eggs could have been fertilized in corf>orc, since no fertilized or segmenting eggs or embryos were seen at the time the animal was opened. However, as soon as the eggs and sperm were free in the sea water, fertilization took place. Development of the selfed eggs was entirely normal, the plutei differing in no way from Fn;ri<K 1. Topographical scheme showing details of female and male gonad elements of S. franciscanus, viewed from the aboral surface. In March, 1955, a bisexual individual .S. franciscanus was found (R. A. B.) at Pacific Grove. This was the first such individual of this species to be discovered. The gonads were separate as to sex, four ovaries, one testis, and no ovotestis. The distribution of the gonads is shown in Figure 1. The selfed eggs produced normal plutei as did the outcrossing of both eggs and sperm. It is to be noted that this is the first case of bisexuality found in this species. The very short breeding season may be a factor. In addition to these examples of sea urchins, several hermaphroditic individuals of Dendrastcr have been found at Pacific Grove. The first was in (Needham and Moore, 192()), when hundreds of the animals were being used to obtain ma- terial for chemical work. In every case the entire gonadal disk was removed and any disk containing white sperm and red eggs would have been detected at once. Since only one was found, it may be assumed that the inciden
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
