In situ sperm release of the sea cucumber Pearsonothuria graeffei (Semper, 1868) in the southern Philippines

In situ spawning observations are important in understanding the reproductive ecology of marine organisms. Here, we report an opportunistic observation of the male spawning of the sea cucumber Pearsonothuria graeffei (Semper, 1868) on the coral reefs in southern Philippines. In situ sperm release was observed at 13:00 h (n = 1) and at 16:30–17:00 h (n = 3), 3 and 11 days after the full moon of May 2025, at two separate locations. These observations provide insights into the reproductive timing of the commercially and ecologically important sea cucumber species from the Philippines.