Those who have observed the languid pace of seahorses or seadragons swimming might think these fish only hunt slow prey. In fact, the tiny crustaceans on which they feed are extremely quick, capable of velocities over 500 body lengths per second. Instead of speed, the seahorse relies on stealth to capture its prey, as shown in the holographic video above. Seahorses use a pivot method to feed, simultaneously shifting their snouts up and sucking water in to catch their target. But this method of feeding only works for distances of about 1 mm. To get that close in the first place, the seahorse must approach its prey without alerting it. Researchers found that both the seahorse’s head shape and its natural posture create a hydrodynamic quiet zone just off the seahorse’s snout, directly in its strike zone. Fluid velocity and deformation rates in this region are significantly lower than those around the rest of the seahorse’s face when it moves, allowing the fish to sneak up on its prey. These adaptations are remarkably effective, too; the researchers observed that the seahorses were able to position themselves within 1mm of their prey without alerting them 84% of the time. (Video credit: B. Gemmell et al.; via Discover)
Seahorse Hunting
