Horse-eye jack

Photo: Dan Schofield · CC BY

Horse-eye jacks school at Radar Reef in characteristically tight, rotating cylinders of silver and black bodies, using the spur-and-groove structure to ambush baitfish driven over the reef by tidal flow. Their oversized eyes — the feature that gives them their common name — provide exceptional low-light vision, allowing the school to hunt into the dusk period when prey visibility for reef fish is declining. They are highly mobile predators that may cover significant distances between reef systems in a single tidal cycle.