Watch the Life Cycle of a Sea Biscuit
Monday, 14 July 2025
This amazing video presents the life cycle of the sea biscuit Clypeaster subdepressus, as part of a master's thesis project conducted at the Biosciences Institute of the University of São Paulo.
Adult specimens were collected from sand beds in the São Sebastião Channel (São Sebastião, SP, Brazil). Researchers then induced gamete release (eggs and sperm), followed by in vitro fertilisation. The resulting embryonic development was observed under light microscopy in a controlled laboratory setting.
As development progressed, embryos transformed into free-swimming larvae approximately 0.2 mm in width. These larvae were sustained on a diet of microalgae until they reached the stage of metamorphosis. During this stage, a juvenile sea biscuit began forming within the larval body. Once the tiny podia (tube feet) and spines developed, the larva sank and underwent metamorphosis, resorbing its larval tissues in the process.
The juvenile then began life among sand grains, exploring its new benthic environment.
The video footage was captured at the University of São Paulo’s Marine Biology Center (CEBIMar-USP), located in São Sebastião, on the northern coast of São Paulo State, Brazil.
Here's the video - enjoy!
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