Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some bioluminescent bacteria, and terrestrial arthropods such as fireflies. In some animals, the light is bacteriogenic, produced by symbiotic bacteria such as those from the genus Vibrio; in others, it is autogenic, produced by the animals themselves.
The Squaliformes are an order of sharks that includes about 126 species in seven families.
Luciferin is a generic term for the light-emitting compound found in organisms that generate bioluminescence. Luciferins typically undergo an enzyme-catalyzed reaction with molecular oxygen. The resulting transformation, which usually involves breaking off a molecular fragment, produces an excited state intermediate that emits light upon decaying to its ground state. The term may refer to molecules that are substrates for both luciferases and photoproteins.
The bareskin dogfish is a little-known, deepwater dogfish shark of the family Etmopteridae. This species is found in the western Pacific from southern Japan to western and southeastern Australia as well as in New Zealand waters.
The blackbelly lanternshark or lucifer shark is a shark of the family Etmopteridae found around the world in tropical and temperate seas at depths between 150 and 1,250 meters. Compared to other mesopelagic fish predators and invertebrates, the blackbelly lanternshark is thought to reside in shallower, more southern waters. E. lucifer can reach up to 47 centimeters in length and consumes mesopelagic cephalopods, fish, and crustaceans. Blackbelly lanternsharks are bioluminescent, using hormone controlled mechanisms to emit light through ventral photogenic organs called photophores and are presumed to be ovoviviparous. The blackbelly lanternshark has been classified as "Not Threatened" within the New Zealand Threat Classification System.
Etmopterus is a genus of lantern sharks in the squaliform family Etmopteridae. They are found in deep sea ecosystems of the Atlantic, Indian and Pacific Oceans.
The blurred lanternshark is a little-known species of dogfish shark in the family Etmopteridae, found around the world in benthic and pelagic habitats from a depth of 110 m (360 ft) to over 1 km (0.62 mi) down. This shark forms the E. pusillus species group with the smooth lanternshark, which are distinguished from other members of its family by having irregularly arranged, flat-topped dermal denticles that give them a "smooth" appearance. Both species are slender-bodied with long heads, two dorsal fins bearing spines, no anal fins, and light-emitting photophores. The blurred lanternshark is larger, reaching 67 cm (26 in) or more in length. This species feeds on small squid, fishes, and fish eggs, and is ovoviviparous. It has been assessed as of Least Concern by the International Union for Conservation of Nature, because of its wide distribution and lack of threat from fishing pressure.
The smooth lanternshark or slender lanternshark is a species of dogfish shark in the family Etmopteridae, found widely in the Atlantic and Pacific Oceans. It inhabits benthic environments at a depth of 274–1,000 m (899–3,281 ft), and pelagic environments at a depth of 0–708 m (0–2,323 ft). The smooth lanternshark forms a species group with the larger blurred lanternshark, both of which are distinguished from other members of their family by small, irregularly arranged dermal denticles with a truncated shape. This species has a slender, dark brown body with an indistinct black band on the sides over the pelvic fins, and reaches 50 cm (20 in) in length. This slow-growing, ovoviviparous shark feeds on smaller squid, fishes, and fish eggs. Smooth lanternsharks are often caught as bycatch in eastern Atlantic and Japanese commercial fisheries. The International Union for Conservation of Nature (IUCN) has evaluated this species as of Least Concern because of its wide distribution and limited threats.
The velvet belly lanternshark is a species of dogfish shark in the family Etmopteridae. One of the most common deepwater sharks in the northeastern Atlantic Ocean, the velvet belly is found from Iceland and Norway to Gabon and South Africa at a depth of 20–2,490 m (66–8,169 ft). A small shark generally no more than 45 cm (18 in) long, the velvet belly is so named because its black underside is abruptly distinct from the brown coloration on the rest of its body. The body of this species is fairly stout, with a moderately long snout and tail, and very small gill slits. Like other lanternsharks, the velvet belly is bioluminescent, with light-emitting photophores forming a species-specific pattern over its flanks and abdomen. The ventral photophores are thought to function in counter-illumination, which camouflages the shark against predators and prey. The bioluminescent flank markings may play a role in intraspecific communication.
The green lanternshark is a species of dogfish shark in the family Etmopteridae, found in the western central Atlantic Ocean. This species usually occurs on the upper continental slope below a depth of 350 m (1,150 ft). Reaching 26 cm (10 in) in length, the green lanternshark has a slender body with a long, thin tail and low, conical dermal denticles on its flanks. It is dark brown or gray with ventral black coloration, which contain light-emitting photophores that may serve a cryptic and/or social function. Green lanternsharks are thought to be gregarious and may attack their prey, squid and octopus often larger than themselves, in packs. Reproduction is aplacental viviparous, with females giving birth to litters of one to three young. This relatively common shark is an occasional, valueless bycatch of commercial fisheries; currently it does not appear to be significantly threatened by human activities.
The Hawaiian Lanternshark is a species of small squaliform shark in the family Etmopteridae.
The dwarf lanternshark is a species of dogfish shark in the family Etmopteridae and is the smallest shark in the world, reaching a maximum known length of 20 cm (8 in). It is known to be present only on the upper continental slopes off Colombia and Venezuela, at a depth of 283–439 m (928–1,440 ft). This species can be identified by its small size at maturity, long flattened head, and pattern of black ventral markings and a mid-dorsal line. Like other members of its genus, it is capable of producing light from a distinctive array of photophores. Reproduction is aplacental viviparous, with females gestating two or three young at a time. The dwarf lanternshark is not significant to commercial fisheries, but could be threatened by mortality from bycatch; the degree of impact from human activities on its population is unknown.
The fringefin lanternshark is a shark of the family Etmopteridae found in the western central Atlantic from Texas to Florida, northern Gulf of Mexico, and Mexico. It is endemic to this area. It is a deep water shark and is found about 220 to 915 meters below the surface, on the upper continental slopes of the Gulf. E. schultzi is a small shark, about 27–30 cm long and feeds on squid. It is also bioluminescent, which counter-illuminates it and helps with intraspecific interaction. Due to its limited range and the difficulty of collecting deep water species, it has not been evaluated by the IUCN Red List, but due to recent oil spills in the Gulf of Mexico, it is likely that fringefin lanternsharks have decreased in population.
The slendertail lanternshark or Moller's lanternshark is a shark of the family Etmopteridae found in the western Indian Ocean between latitudes 34°N and 46°S at depths between 250 and 860 m. It can grow up to 46 cm in length.
The great lanternshark is a shark of the family Etmopteridae found in the northeast and northwest Atlantic. Its name was given because, at the time of its discovery, it was thought to be bioluminescent, but this has been challenged.
The brown lanternshark or bristled lanternshark is a little-known species of deep-sea dogfish shark in the family Etmopteridae. It is found off Japan and New Zealand, and possibly also South Africa and Australia, typically deeper than 300 m (980 ft). This species can be distinguished from other lanternsharks by its coloration, which is a uniform dark gray or brown without the ventral surface being much darker and clearly delineated from the rest of the body. The brown lanternshark feeds on small bony fishes, cephalopods, and crustaceans. Reproduction is ovoviviparous, with females giving birth to 9–18 young. An unusually high proportion of individuals in Suruga Bay are hermaphrodites, with both male and female characteristics.
The blackmouth lanternshark is a species of dogfish shark within the family Etmopteridae. This species is part of a subgroup that includes one other species from within the family. It is known to inhabit the benthic zones of the Eastern Indian Ocean and the Arafura Sea. These sharks were first described in a 2002 issue of Cybium: International Journal of Ichthyology, and there is still much unknown about the species.
Counter-illumination is a method of active camouflage seen in marine animals such as firefly squid and midshipman fish, and in military prototypes, producing light to match their backgrounds in both brightness and wavelength.
Eukrohnia fowleri is a deep-sea marine arrow worm. It is the only known bioluminescent member of the genus Eukrohnia, and one of the two known species of bioluminescent arrow worms, the other being the distantly related Caecosagitta macrocephala. The bioluminescent organ of Eukrohnia fowleri is found along the center of its tail fin on both its dorsal and ventral side. It has a secreted bioluminescence that is thought to be coelenterazine based. While both species use luciferases in conjunction with coelenterazine for light emission, the luciferase of Eukrohnia fowleri is highly stable after 30 minutes while the luciferase of Caecosagitta macrocephala becomes inactive. So far, there is no other bioluminescent organism that uses hexagonal packing in order to hold bioluminescent materials/ E. fowleri evolved through the adaptation to hypoxic water and due to the recent oxygenation of water they have been experiencing bottleneck events. These events have been seen as one of the reasons that E. fowleri have such low biodiversity.
Caecosagitta macrocephala is a deep sea marine chaetognath that is distributed in meso- and bathypelagic layers. It has a very wide distribution that ranges from the Subantarctic to Subarctic Ocean. Cecosagitta macrocephalas have large heads, hence their name “macro-cephala”. Within their eyes are photoreceptive regions that allow them to catch weak light at bathypelagic depths. Along with their eyes, their gut or intestine has orange pigmentation and a luminous organ that gleams due to bioluminescence unlike some other species of Sagittidae. To be more precise, the luminescent organ is located on the ventral edge of each anterior lateral fin. It is the only member of the genus Caecosagitta, and only one of the two known species of bioluminescent chaetognath, the other being the distantly related Eukrohnia fowleri. C. macrocephala has a secreted bioluminescence that is thought to be coelenterazine based. The luciferase is highly unstable, being unable to survive a single freeze-thaw, and is rapidly inactivated at ice-cold temperatures.
