In addition to defense, the nematocysts are used to catch prey. During feeding, the tentacles may be draped onto the sand, where they passively capture small fish and crustaceans. When the prey is entangled, the tentacles contract and shorten, and then through muscular and ciliated action, the prey is brought inside the bell and eaten. They may also actively pursue prey. They are capable of directed swimming, and are among the fastest jellies, clocking in at speeds of four knots. These jellies also possess a true eye, including a retina, cornea and lens, which allows them to recognize specific points of light.
Box jelly "invasions" have been on the rise in O'ahu for the past twenty or so years. To learn more, local lifeguards teamed up with a marine scientist, and with help from the aquarium, they were able to collect data to determine that the invasions are linked to a lunar and tidal pattern. Expect a visit from Carybdea alata about ten days after the full moon each month. And have some vinegar on hand just in case.