Due to the small size of the adults (only 3-5 mm), they utilize a different reproductive strategy than larger sea stars. Instead of investing energy in producing large numbers of small eggs to free-spawn into the water column (and allow them to develop into feeding ophiopluteus larvae - as pictured in the next post), these small animals produce only a few small eggs (about 100 μm) in each gonad, and invest energy in brooding them internally until they are large enough to crawl away. Although it is a larger investment per egg, this direct development strategy ensures that the young develop to the juvenile stage. Amphipholis squamata can brood multiple cohorts simultaneously, and in our dissections we found brooded young in multiple stages of development within the same adult brittle star.
Amphipholis squamata is also interesting because it is a simultaneous hermaphrodite and appears to be capable of self-fertilization. The grey colored adult brittle stars feed on diatoms and detritus, and can be found under small rocks on sand or gravel in intertidal zones worldwide (Kozloff 1974).
Kozloff, E.N. 1974. Seashore Life of the Northern Pacific Coast; an illustrated guide to northern California, Oregon, Washington and British Columbia. U of Washington P: Seattle.