Stoplight Loosejaw - Oceana

Ocean Fishes

Stoplight Loosejaw

Idiacanthus antrostomus


Worldwide in tropical to sub-polar latitudes


Deep sea/open ocean (mesopelagic to bathypelagic)

Feeding Habits

Ambush predator


Order Stomiiformes (dragonfishes and relatives), Family Stomiidae (barbeled dragonfishes)


The stoplight loosejaw is named for the two specialized light-producing organs that are located below each eye. One is green and one is red. Producing light in these two colors increases the ability of the stoplight loosejaw to see and attack its prey. There is very little light at the stoplight loosejaw’s preferred depth – 1700 to 13,000 feet (500-4000 m) below the sea surface. This species likely utilizes its light organs to visually locate prey. The red organ, in particular, is valuable because most species at those depths cannot see red light. A red crustacean, for example, would be easy to see in red light, even if the crustacean cannot sense the light itself. Adult stoplight loosejaws are less than one foot (30 cm) long and eat small fishes and crustaceans. The stoplight loosejaw uses its long, needle-like teeth and unique jaws to ensure that no passing meal is too big to miss. Unlike some closely related fishes that migrate toward the surface each night, scientists believe that the stoplight loosejaw stays in the deep.

Like most species in the deep sea, the stoplight loosejaw is very difficult to study and is only known from specimens that are brought up from deep nets. Stoplight loosejaws are not eaten by people, and there is no evidence to suggest that people have any negative affects on their populations. However, the deep sea is known to be a changing environment, so it is important for scientists to continue monitoring this large marine habitat.

Engage Youth with Sailors for the Sea

Oceana joined forces with Sailors for the Sea, an ocean conservation organization dedicated to educating and engaging the world’s boating community. Sailors for the Sea developed the KELP (Kids Environmental Lesson Plans) program to create the next generation of ocean stewards. Click here or below to download hands-on marine science activities for kids.

Kids Environmental Lesson Plans

Additional Resources:

IUCN Red List