The animal came up from about 165 metres with its jaws full of parachute fabric. Nothing about it fitted: a broad, blunt head, a mouth over a metre wide lined with tiny hooked teeth, soft flabby musculature and a body more than four metres long. Taxonomists erected Megachasma pelagios and the family Megachasmidae to hold it.
It is the third of the three filter-feeding sharks, alongside whale and basking sharks, and takes euphausiid krill and small fish. The mouth interior is pale and reflective, and a luminous or reflective band along the upper jaw has been suggested as a lure, though this is speculative.
Sightings remain rare. Fewer than three hundred records exist worldwide after nearly fifty years, and only a handful have been observed alive and free-swimming. Its distribution, breeding and true abundance are essentially unknown, which is why the Least Concern listing reflects a lack of documented threat rather than a measured healthy population.