Netted daggertooth specimens are rarely identifiable, mostly because of their soft bodies, which are easily torn or flattened.

In fact, the bodies are so soft, when pushed against the back of a trawl net, they often die because their organs are crushed and they rip.

The species undergoes metamorphosis, whereupon they become black in colour, become toothless, stop feeding, develop very large gonads and the gastrointestinal tract atrophies.

This was discovered in 1971, after German ichthyologist Günther Maul caught such a specimen off Madeira that measured 75.9 cm.

The apparent rarity of specimens caught during this last stage of life may be a result of the combination of the cessation of feeding and the migration to deeper depths, making them difficult to catch.