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Marine Animal Encyclopedia

Pacific Blackdragon Idiacanthus antrostomus

The Pacific Blackdragon is a deep-sea predator that lives in the deep waters of the eastern Pacific Ocean from about 700 to 3300 feet (200-1000 m) deep. Though they spend most of their time in these deep waters, Pacific Blackdragons are known to migrate toward the surface, at night following their preferred prey of small crustaceans and other fishes.

As they are ambush predators, their bodies are dark black, and even their stomachs are coated with black tissue to block out any light that might be produced by bioluminescent (light producing) animals that they eat. Along their dark bodies, Pacific Blackdragons have several rows of specialized light cells, called photophores that are probably used to attract mates. They have a separate light organ at the end of the long barbel that hangs down from the chin. This organ is used as a lure to attract prey toward their teeth-filled mouths. Adults reach approximately two feet (60 cm) in length and are skinny and eel-like, though these fish are not closely related to true eels. Even though it lives in deep waters, the preferred depths of the Pacific Blackdragon receive some sunlight during the day, so the eyes are large and well developed.

Interestingly, most of the above characteristics of the Pacific Blackdragon only apply to the females. The males are much smaller; have no teeth, stomach, or barbel; and are unable to feed. They never really leave the larval stage of development, and all of their energy comes from the egg yolk. Males only live long enough to mate, soon after which they die. This extreme difference in the sexes has been documented in other deep-sea species as well and may be a means to reduce competition for limited resources while preserving the importance of mixing genes through sexual reproduction. Larvae of both sexes have extraordinary, stalked eyes that they absorb as they mature into young juveniles.

Pacific Blackdragons are not eaten by people, and there is no evidence to suggest that people have any negative affects on their populations. They are likely naturally rare, however, and any changes to the deep-sea environment could threaten this interesting species.

Pacific Blackdragonzoom image
  • Distribution eastern Pacific Ocean from California to Chile
  • Ecosystem/Habitat deep sea/open ocean (mesopelagic)
  • Feeding Habits ambush predator
  • Conservation Status unknown but likely stable
  • Taxonomy Order Stomiiformes (dragonfishes and relatives), Family Stomiidae (barbeled dragonfishes)
Pacific Blackdragon habitat mapzoom image