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Hawaiian Spotted Eagle Ray, Bonnet Ray, Duck Bill Ray

Hihimanu

The Hawaiian spotted eagle ray is also known as the bonnet ray, duck bill ray, or spotted duck billed ray, but perhaps no other name than hihimanu describes them so perfectly. This Hawaiian name means “magnificent” or “elegant bird.” With the grace of an eagle, this cartilaginous fish can be found gliding in shallow coastal waters ranging throughout the Hawaiian island chain to at least the Midway Atoll. The maximum span of their “wings,” or pectoral fins, is six feet from tip to tip, and their coloration is stunning. White spots adorn a solid black background creating a dramatic topside pattern. Their bellies are a brilliant white with a black, geometric maze pattern on the underside of each wing. Their wing tips can be observed breaking the water’s surface as the prelude to a breathtaking skyward launch, followed by an end-over-end mid-air cartwheel display.

Although the spotted eagle ray has a long whip-like tail with one or more barbed spines at the base, it is not classified as a true stingray. Hawaiʻi’s three species of stingrays display venomous spines much further down the length of their tail. Hawaiian eagle rays are considered to be very docile and will often swim away when approached by divers. However, their barbed spines can be extremely painful if touched.

Did You Know...
The hihimanu feed in soft sand sediments, using their fleshy, shovel-shaped snout to dig up clams and oysters.

 

The same electroreceptor system found in sharks and other rays, the ampullae of Lorenzini, works similar to a metal detector and assists in locating electrical fields given off by their often buried prey. These sensory pores, located under the jaw and snout, also enable them to sense the earth’s magnetic field and aid in navigation. Another sense that sharks and rays share is a water-motion detector system called the lateral line. Located in the lateral line canal, this system consists of a series of canals running along the side of the animal’s body. A series of cells called neuromasts interpret information through vibrational changes in the water, allowing the ray to feel not only nearby prey but approaching predators and their own movements as well.

Spotted eagle rays feed on snails, shrimp, crabs, and sea urchins. Their flat, hard teeth plates are specially equipped to crush the shells of their prey. The shells are then spat out, and the remaining meat is swallowed. Researchers have observed that male teeth plates are slightly more pointed than the females, which may lend itself to the mating ritual in which the male bites the trailing edge of the female’s wing and holds on during mating (which lasts approximately one minute).

These rays reach reproductive maturity at four to six years of age. Embryos develop only in the left uterus of female rays, where they are nourished by uterine milk. Hihimanu give live birth to a litter of one to four pups, each displaying a 10-20 inch wingspan. Exciting aerial displays have been associated with the birthing process, in which the mother leaps out of the water and expels the pups in mid-air. The newborns arrive into the world with their wings wrapped bat-like around their bodies, which they quickly unfold and use to begin to swim to avoid their main predators; sharks.

In addition to sharks (primarily the tiger shark in Hawaii), their main threats are fishing, accidental by-catch, and entanglement. Although their flesh is edible, it is not desirable, and they are more often sought after for oil or fishmeal.

*Due to the constant rotation of animals back to the ocean, we cannot guarantee the presence of any specific animal.

Hawaiian Name:
Hihimanu
Scientific Name:
Aetobatus narinari
Where to See:
Open Ocean*
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