Opahs and Relatives: Lampridiformes

Physical characteristics: Oarfish are spectacular animals with long, slender, usually silver bodies, brilliant red fins, a large plume of dorsal fin rays on the head, and long pelvic or back fins. Often attaining a length of 26–33 feet (8–10 meters), oarfish are the longest of all bony fishes. The pelvic fin ray has a large red swelling at its tip that looks like the blade of an oar. The tail fin is tiny, but it has very long rays that are covered in small spines. Oarfish have about four hundred dorsal (DOOR-suhl) fin rays and 150 vertebrae (ver-teh-BREE), which are the small bones that make up the spinal column. The dorsal fin is the fin along the midline of the back. The pelvic fins are the rear pair, corresponding to the rear legs of four-footed animals. Rays are the supporting rods in fins.

Geographic range: Oarfish live in all oceans, including the Mediterranean Sea, but not in polar seas.

Oarfish are spectacular animals with long, slender, usually silver bodies, brilliant red fins, a large plume of dorsal fin rays on the head, and long pelvic or back fins. (Illustration by Wendy Baker. Reproduced by permission.)

Habitat: Oarfish live in open water near the surface to depths of about 656 feet (200 meters).

Diet: Oarfish eat crustacean plankton and small fishes.

Behavior and reproduction: Oarfish move by wavy movement of the dorsal fin. The natural body position is head up with the dorsal fin rays and pelvic rays extended outward; the fish swim up and down in the water this way. The pelvic fin may allow oarfish to "taste" the surrounding habitat. Scientists know little about the reproduction of oarfish. The eggs drift in open water and have been found in plankton collections. Researchers report that eggs can take up to three weeks to hatch and that the larvae are close to their adult form at hatching.

Oarfish and people: Sightings of oarfish usually stir considerable public attention, but the species has no commercial value, and its meat is reported to be inedible.

Conservation status: Oarfish are not threatened or endangered. ∎