This ghostly giant is a rare sight.

Out of the darkness of the ocean’s midnight zone, MBARI’s remotely operated vehicle (ROV) Doc Ricketts spots a billowing crimson curtain. Moving in for a closer look, the submersible’s lights reveal the giant phantom jelly (Stygiomedusa gigantea). The bell of this deep-sea denizen is more than one meter (3.3 feet) across and trails four ribbon-like oral (or mouth) arms that can grow to more than 10 meters (33 feet) in length. MBARI’s ROVs have logged thousands of dives, yet we have only seen this spectacular species nine times.

The first specimen of the giant phantom jelly was collected in 1899, but it was not until 60 years later that scientists recognized this as a new species. Even now, scientists still know very little about this animal.

MBARI’s observations of Stygiomedusa gigantea have helped illuminate its ecological role in the ocean’s depths. During an expedition to the Gulf of California, MBARI’s ROV Tiburon recorded a fish—the pelagic brotula (Thalassobathia pelagica)—alongside a giant phantom jelly. Researchers watched the brotula hover above the bell of its host and swim in and out of the jelly’s voluminous oral arms. The wide-open waters of the midnight zone offer little shelter, so many creatures find refuge in the gelatinous animals that are abundant in this environment.