Brooding behavior in the shallow‐water brittle star Ophioderma wahlbergii

Brooding behavior and the brooded young of Ophioderma wahlbergii, a common, large, shallow‐water brittle star from South Africa, are described for the first time. Monthly samples of 20 specimens were collected from June 2013 to May 2014 (n=240 in total). The species was shown to be gonochoric. Females reached maturity at 17 mm disc diameter (dd), and their ovaries contained 5±3 yolky eggs of mean diameter 0.25±0.1 mm. No seasonal trends in reproduction were found, and >50% of females examined in each month were brooding. Brooding individuals contained an average of 7±6 and up to 33 developing young. Small stages were more frequent than larger young, suggesting that juveniles either emerge at different sizes, or more likely suffer mortality during development. Young within individual adults were of different clutches, but those within individual bursae were all of the same stage. No signs of larval stages were found, indicating that development is direct. Given the large size of emerging juveniles, the species is likely to be matrotrophic and hence truly viviparous. Brooding is a recent discovery in Ophioderma and, so far, the only known brooder has about 1000 small embryos. This study shows quite a different reproductive strategy within the genus, with few, large eggs developing into the largest brooded young known from any species of ophiuroid.