Stoplight Loosejaw
Overview
The stoplight loosejaws are deep-sea fish belonging to the genus Malacosteus, part of the subfamily Malacosteinae within the family Stomiidae, or in some classifications, the separate family Malacosteidae.
- Habitat: Found worldwide (except Arctic and Subantarctic regions) in mesopelagic and bathypelagic zones, usually below 500 meters.
- Species: Originally three species, now revised to two: M. niger and M. australis.
Taxonomy
- Domain: Eukaryota
- Kingdom: Animalia
- Phylum: Chordata
- Class: Actinopterygii
- Order: Stomiiformes
- Family: Stomiidae
- Subfamily: Malacosteinae
- Genus: Malacosteus (established by Ayres in 1848)
Distribution and Habitat
- M. niger: Found between 66°N and 33°S, absent in the Mediterranean Sea.
- M. australis: Resides in the southern transition zone (25° to 45°S) near the Antarctic Circumpolar Current.
- Found as deep as 3886 meters and do not migrate vertically.
Physical Characteristics
- Body Structure: Elongated body, large eyes for binocular vision, one nostril per side.
- Jaw: Wide gape with fang-like teeth, aids in catching prey.
- Fins: Moderately long pectoral and pelvic fins, dorsal and anal fins placed far back.
Bioluminescence
- Unique in producing red bioluminescence, invisible to most prey.
- Uses a chlorophyll derivative to perceive red light, unique among animals.
- Photophore arrangement: Red, green, and blue photophores resembling traffic lights.
Feeding and Behavior
- Diet: Primarily zooplankton (copepods, krill, shrimps, fish).
- Hunting Strategy: Uses red light to illuminate prey undetected.
- Jaw Mechanism: Allows quick, wide gape for capturing prey.
Unique Adaptations
- Visual System: Uses a chlorophyll-derived photosensitizer for long-wave light.
- Feeding Mechanism: Adapted to snatch prey with minimal resistance.
- Respiration: Exposed gills allow respiration while swallowing large prey.
Research and Studies
- Kenaley's 2007 study revised the genus classification to two species.
- Studies indicate the dietary origin of Malacosteus' visual system and bioluminescence.
These notes provide a comprehensive overview of the stoplight loosejaw, highlighting its habitat, taxonomy, physical and behavioral characteristics, and unique adaptations that allow it to thrive in deep-sea environments.