Hong Kong conservationists on Wednesday began underwater tracking of endangered horseshoe crabs, which date back to before the dinosaurs, in a bid to help them survive the perils of modern life. Of four species worldwide, the Chinese horseshoe crab (tachypleus tridentatus) and the mangrove horseshoe crab (carcinoscorpis rotundicauda) are found in Hong Kong coastal waters. The Ocean Park Conservation Foundation (OPCFHK) said it had initiated the first underwater automated acoustic "telemetry system" for a pilot tracking study.