Stoplight Loosejaw: The Bottom-Dwelling Dragonfish

selim12 December 28, 2023 0 Comments

The stoplight loosejaw is a small, deep-sea dragonfish of the genus Malacosteus. This fish has the great advantage of hunting in deep with invisible light as prey is almost blind in those remote depths.

Table of Contents

Where Do They Live:

They are found worldwide starting from 500 meters depth; outside of the Arctic and Subantarctic, in the mesopelagic zone.

Appearance and Size Of The Stoplight Loosejaw:

They have a long body with short snouts and large eyes facing forward. They can produce red bioluminescence. They have a very elongated lower jaw measuring one-quarter of the fish’s length.It has fang-like teeth in the front of the jaws. The pectoral and pelvic fins are moderately long, containing 3–4 and 6 fin rays respectively. It has three bioluminescent photophores near the eyes. They also have a photophore emitting green light in depths to attract prey and mates. This fish can see red color thanks to a specific photophore on the head. It has lower mandible making the quarter length of the body.

Stoplight Loosejaw Diet:

They eat zooplankton, chiefly large calanoid copepods, with smaller numbers of krill, shrimps, and fish. In-depth, every meal counts as food is less frequent.

LifeSpan And Behaviour:

This fish doesn’t migrate vertically into more productive waters like other stomids. It’s favorite snack is copepods. They can emit far-red light at 708 nm, making it essentially invisible to its prey(the red light is absorbed by the ocean’s photic zone,plus the prey is blind when it comes to red light). The red photophore of Malacosteus consists of a pigmented sac with a reflective inner lining and an internal mass of gland cells. They can live up to 20 years.

Biology and Ecology:

The red photophore allows the spotlight loosejaw to detect prey in silence. The lower open jaws help to swing the entire head of the prey forward reducing water resistance with recurved teeth assuring the grab on the victim.No way out of that deadly mouth. It has outside gills to ensure respiration while feeding. The pectoral and pelvic fins are moderately long, containing 3–4 and 6 fin rays respectively. The photophores are larger in males than females. They rely on chemosynthesis.

Reproduction & LifeCycle:

After fertilization, the fertilized eggs develop into larvae. These larvae may undergo a planktonic stage, drifting in the ocean currents, before eventually developing into juvenile dragonfish.

Research and Discoveries:

Research has discovered that the red photophore of Malacosteus consists of a pigmented sac with a reflective inner lining and an internal mass of gland cells with blue light in gland cells. Another name for this fish is rat-trap fish due to their unusual open jaws.

Conservation Status:

This fish is far from threatened as it’s in the deep ocean and away from human interaction(sometimes, it’s caught in deep-sea fishing nets.

Cool Facts About The Stoplight Loosejaw:

-They spent most of their lives in the darkness of the deep.

-This fish doesn’t migrate to shallower waters spending almost all her lifecycle in deep waters.

-The genus Malacosteus contains two species M. niger and the new M. australis.

-The larger recorded specimen is 25 cm length.

This fish is a master of camouflage in the depths and is considered one of the deadliest deep sea fish as it devours it’s prey with no chance of survival thanks to its quickness.