Would the sea robin eat the ophiuroid? The story of the brittle star and the sea robin

In undersea exploration, you never know when you might witness a moment of unusual creature interaction

While conducting the an expedition in Puerto Rico, NOAA’s research vessel, Okeanos Explorer, performed exploratory dives with its remotely operated vehicles – Deep Discoverer and Seirios. Scientists from all over were able to watch via telepresence technology direct from their site.

The sixth dive was east of the island, just off the continental coast, at an approximate depth of 600 meters. The priority of this dive was to image a platform carbonate sequence and fault scarp, during which remarkable biota was documented as well. One momentous occasion occurred not long into the dive between two different species of marine life.

At a depth of 576 meters, NOAA’s skilled ROV pilots maneuvered the vehicles to gain a better view of an armored sea robin. As the videographer zoomed in we also noticed an ophiuroid laying nearby. While science lead Andrea Quattrini touched on some of the known facts about armored sea robins, the brittle star began to move onto the front barbels of the fish’s face. The fish responded by opening its mouth and raising itself up on its feelers. With a question of predation on our minds, we watched as the sea robin hastily shook the brittle star from his barbels and moved away. As the sea robin began anew to nestle into the sediment, the brittle star lumbered close and once again climbed on. This time with less hesitation, the sea robin freed itself and left the brittle star in the dust. After a few seconds passed, the D2 and Seirios moved on. (Watch the video below)

The first question to ask is, naturally, “Would the sea robin eat the ophiuroid?” Since sea robins are only known to feed on crustaceans the chance of it finding the spindly and meatless brittle star delectable is obviously very small. Some suggest the sea robin’s actions were attempts to frighten the bothersome creature away.

But another question might be to ask what the brittle star’s intentions were. Dr. Christopher Mah, an Echinoderm expert, notes the irregularity in the ophiuroids behavior in raising itself up on its arms, which they do customarily to feed or in spawning. But he concludes that the whole incident was most likely coincidental.

Whatever reason the two may have had in being in the same place, it was an incredible opportunity to observe nature in situ, and will no doubt aid in furthering our understanding of the two very different species.