This video is nothing short of incredible – the lifecycle of a sea biscuit filmed entirely under a microscope (more).
We collected adults from sand beds of São Sebastião Channel (São Sebastião, SP, Brazil) and induced gamete release (eggs and sperm). We did the fertilization in vitro and followed the embryonic development in the laboratory, under light microscopy. Embryos become swimming larvae, approximately 0.2 mm wide, which we fed with microalgae until metamorphosis. A diminute sea biscuit grows inside the larva. When the minuscule podia and spines are formed the larva sinks and undergoes metamorphosis. The juvenile sea biscuit resorbs the larval tissue and begins to explore its new habitat, between sand grains.