Sexual reproduction involves the liberation of sperm and eggs into the sea and the development and eventual settlement of planktonic larvae. Asexual reproduction is by fragmentation, each portion being the same sex as its parent. Small, immature individuals (disc diameter under ) usually have six arms and can split themselves in two and then regenerate the missing parts of the disc and arms, often ending up with five arms. Most larger individuals have five arms and can also undergo fragmentation. The larger males do so more often than do the females, and this may account for the fact that there is an excess of males in the population. After splitting, the brittle star may still be able to reproduce sexually but some fragments of the disc may have no gonads and thus be unable to spawn until regeneration is complete. In Taiwan, mature gametes occur at any time from March to December, but most of the population of "O. savignyi" spawn during May and June. Fission takes place at any time of year but mostly occurs between July and December. Sampling the brittle stars throughout the year resulted in finding that 48% of the individuals inspected were in the process of regeneration. The sex ratio in this locality is twenty-four males for every one female. In Hawaii, this brittle star is often to be found living in association with a sponge such as "Lissodendoryx schmidti" (previously "Damiriana hawaiiana"). Up to twenty individuals can be found clumped together in cavities in the base of the sponge, the area being so filled with the slime secreted by the sponge that the brittle stars can hardly move their arms. These brittle stars often seem to have broken or partly regenerated arms. It is not clear how they enter the sponge, nor how they feed or reproduce.