Taillight Gulper, Saccopharynx ampullaceus

The latin name for this species is very descriptive. Sacco, means "to strain through a bag", pharynx is "mouth", and ampullaceus means "big-bellied". These terms aptly portray the appearance of the taillight gulper, which is dominated by an enormous mouth, and a large sac-like abdomen. This fish is very long, growing to 1.6 m in length, most of which is taken up by its long, whip-like tail. It is black in colour, has small eyes, and a single light organ on its tail – hence its common name. It is easily distinguished from the related pelican gulper by the curved teeth that line its jaws, and the filaments of skin that extend in varying lengths from its upper body.

Living at depths of 2000 m or more, this deep-sea fish is one predator that is able to tackle fishes that are bigger in size than itself! However, once in the hunt for a mate, sexually mature taillight gulpers no longer feed. They lose their teeth, and their abdomen and jaws shrink in size, as valuable nutrients are absorbed. The sensory organs that detect smell greatly enlarge in males, an indication that mate location in this species is likely precipitated by the release of pheromones by females. The larvae are perhaps more readily encountered than the odd-looking adults, as the leaf-shaped immature stage occupies shallower waters before descending to the depths.