Why a shark sighting near Tonga just rewrote the depth record for an entire shark order

A single shark sighting near the Tonga Trench has just rewritten what scientists thought they knew about how deep an entire order of sharks can live. The animal in question was a goblin shark, one of the ocean’s rarest and strangest-looking predators, filmed alive and healthy far below its previously known range.

The discovery, published in the Journal of Fish Biology by a team from the University of Hawai’i at Mānoa, found the goblin shark nearly 700 metres deeper than the species was ever documented before. According to lead author Aaron Judah, a doctoral candidate at UH Mānoa’s Deep-Sea Animal Research Center, the observation also set a new depth record for the entire order of Lamniformes, commonly known as mackerel sharks — a group that includes the great white shark, basking shark and mako shark.

Goblin sharks (Mitsukurina owstoni) are considered living fossils, the only surviving members of a shark lineage stretching back roughly 125 million years, recognisable by their long, flattened snout and protruding jaws. Until this study, no one had ever filmed one alive in its natural habitat; every previous sighting came from sharks accidentally caught in fishing gear, which usually died shortly after being brought to the surface.

The Tonga Trench shark was one of two documented in the study. The other was spotted near a seamount close to Jarvis Island in the Central Pacific, in footage that had gone unrecognised in an archive for years before researchers realised what they were looking at.

Judah said seeing the species alive and healthy in the wild was “a unique honor,” and that the two sightings, hundreds of kilometres apart, suggest goblin sharks occupy a much wider range across the Pacific than scientists had previously believed.