Photoblepharon palpebratum

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Photoblepharon palpebratum
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Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Trachichthyiformes
Family: Anomalopidae
Genus: Photoblepharon
Species:
P. palpebratum
Binomial name
Photoblepharon palpebratum
(Boddaert, 1781)
Synonyms
  • Photoblepharon palpebratus(Boddaert, 1781)
  • Sparus palpebratusBoddaert, 1781 [2]

Photoblepharon palpebratum (Syn. P. palpebratus), the eyelight fish or one-fin flashlightfish, is a species of saltwater anomalopid fish of the order Beryciformes. It is native to the western and central Pacific Ocean where it is found along seaward reefs close to the ocean floor, usually near rocks and corals it can use as cover. At only 12.0 cm (4.7 in) in length, it is a small fish, and more stout than other members of its family. Its body is mostly black, with a line of reflective scales running the length of its body and a distinguishing white spot at the upper corner of its preopercle. Its most notable features are its subocular bioluminescent organs which it likely uses to attract and find prey, confuse predators, and communicate with other fish. These organs are blinked on and off by the fish using a dark lid that slides up to cover them.

Contents

The eyelight fish is a nocturnal predator, spending the day hidden in caves and crevices in the rock, and emerging at night to search for food. It generally hunts in large groups away from the reef. Like other members of Animalopidae, reproduction is oviparous. Mated pairs spawn near the ocean surface and females can produce as many as 1,000 eggs per cycle. It is of little commercial value, its only real use being as bait for local fishermen. The eyelight fish has been displayed in public aquariums. It is listed as Least Concern by the International Union for Conservation of Nature (IUCN) due to an extensive range and lack of threats.

Taxonomy and phylogeny

The first scientific description of the eyelight fish was authored by Dutch naturalist Pieter Boddaert in his 1781 piece, Beschreibung zweier merkwürdiger Fische, part of the larger volume Neue Nordische Beyträge zur physikalischen und geographischen Erd- und Völkerbeschreibung, Naturgeschichte und Oekonomie, 2 by German zoologist Peter Simon Pallas. [3] He named the species Sparus palpebratus, its generic name being the Latin word "sparus" meaning "a fish with a golden head." It was later assigned to the genus "Photoblepharon" by German-Dutch zoologist Max Carl Wilhelm Weber in 1902. Its current genus name derives from Greek: "photo" meaning "light" and "blepharon" meaning "eyelash." Its congener, P. steinitzi , was originally classified as a subspecies of this fish, P. palpebratus steinitzi. It was reclassified as its own species in 1987 by ichthyologists John E. McCosker and Richard H. Rosenblatt. [2] [4]

Anomalops

Phthanophaneron

Kryptophanaron

Photoblepharon palpebratum

Photoblepharon steinitzi

Phylogenetic tree of Anomalopidae. [5]

The eyelight fish is considered one of the more derived members of Anomalopidae, most closely related to Krypotophaneron with the exception of P. steinitzi. Its reflective lateral-line scales are shared by Kryptophaneron and Phthanophaneron, but are enlarged for only Kryptophanaraon and Photoblepharon, indicating that they are a unique trait of the two. Refinement of the shutter mechanism down the cladogram is further confirmation of its placement of genera. [5]

Description

Photoblepharon palpebratum in the dark. Photoblepharonpalpebratum (cropped).JPG
Photoblepharon palpebratum in the dark.

The eyelight fish is a small, dark fish, with a relatively stout body for an anomalopid. It has a blunt snout, large eyes, and prominent subocular light organs. It has a single dorsal fin and no adipose fins. It has 2–3 dorsal spines, 16–20 dorsal rays, 2 anal spines, and 13–15 anal soft rays. Most of its body is black, but it is marked by a distinct white spot at the upper corner of its preopercle, as well as by a lateral line of reflective scales and white scales in front of its pectoral fins. Its maximum length is 12.0 cm (4.7 in), making it one of the smaller members of its family. [2]

It is distinguished from its congener, P. steinitzi, in a number of ways, one indicator being the white spot on its preopercle. P. steinitzi has either no white spot or a smaller, darker spot, as well as more ornamented head bones. [4]

Its most distinguishing features are the cream-colored light organs underneath its eyes, which produce blue-green light likely used by the fish to attract prey, communicate with other fish, and frighten and confuse predators. These organs contain bioluminescent bacteria, fed by oxygen and nutrients from the fish's bloodstream, [6] which emit a constant light. The eyelight fish uses a black lid to cover the organs when it does not want to emit light. [5]

Distribution and habitat

The eyelight fish has a wide range in the western and central Pacific Ocean, from the Philippines in the west to the Society Islands in the east, as well as south to New Caledonia. Its latitudinal range is between 19°N and 24°S. [2] It was originally thought to be found only in Indonesia, but has since been seen near Guam and caught off the coasts of Australia, the Marshall Islands, the Caroline Islands, the Cook Islands, and Papua New Guinea. Because its nocturnal habits make sightings and collections uncommon, the extent of its range is not fully understood, and likely contains other localities. [4]

It lives in or near seaward reefs with steep drop-offs and caves, [2] and is generally found alone or in pairs. [7] When hunting it remains close to the ocean floor. [5] Its preferred water temperatures are between 18 and 29 °C (64 and 84 °F). [8] It is usually seen by humans no deeper than 15 m (49 ft), but its depth range extends as far as 50 m (160 ft) below the surface. [2]

Biology and ecology

The eyelight fish spends the day hidden in caves and crevices and emerges at night to feed, generally in large groups away from the reef. [2] Its primary food source is likely crustaceans it finds or attracts with its light organs. [9] Like other anomalopids, the eyelight fish's reproduction is oviparous. Mated pairs spawn near the water's surface. Each female can lay up to around 1,000 eggs per spawning. These eggs go through a brief planktonic phase before attaching to a nearby surface. Within a day, eggs turn milky white and sink to the substrate. Spawning has been documented in the early months of April and May, though it is likely the fish spawns at other times during the year as well. [10]

The symbiotic bacteria in its light organs differ substantially from the bacteria found in other anomalopids. [11] Some bacteria are released from its light organs and remain viable after being discharged, but cease to emit light shortly thereafter. [12] To shut off the light, the eyelight fish uses black lids that slide up to cover the light organs. Use of only a black lid is unique to Photoblepharon; the other members of its family either rotate the organ into a pouch or employ a pouch-and-shutter method. [5]

Human interactions

The eyelight fish has little interaction with humans. Besides being harmless, it spends the day hidden in rock crevices and so is rarely encountered by divers. [2] It has little commercial value, its primary use being as bait for local fisheries, which will cut out the light organs and attach them to hooks. [13] Previously listed as Data Deficient by the IUCN, in 2020 the eyelight fish was updated to Least Concern because of its extensive distribution and lack of major threats. [1]

Related Research Articles

<span class="mw-page-title-main">Anomalopidae</span> Family of fish (Anomalopidae)

Anomalopidae are a family of fish distinguished by bioluminescent organs located underneath their eyes, for which they are named. These light organs contain luminous bacteria and can be "shut off" by the fish using either a dark lid or by being drawn into a pouch. They are used to communicate, attract prey, and evade predators.

<span class="mw-page-title-main">Beryciformes</span> Order of fishes

The Beryciformes are a poorly-understood order of carnivorous ray-finned fishes consisting of 7 families, 30 genera, and 161 species. They feed on small fish and invertebrates. Beyond this, little is known about the biology of most member species because of their nocturnal habits and deepwater habitats. All beryciform species are marine and most live in tropical to temperate, deepwater environments. Most live on the continental shelf and continental slope, with some species being found as deep as 2,000 m (6,600 ft). Some species move closer to the surface at night, while others live entirely in shallow water and are nocturnal, hiding in rock crevices and caves during the day. Several species are mesopelagic and bathypelagic. Beryciformes' bodies are deep and mildly compressed, typically with large eyes that help them see in darker waters. Colors range from red to yellow and brown to black, and sizes range from 8–61 cm (3.1–24.0 in). Member genera include the alfonsinos, squirrelfishes, flashlight fishes, fangtooth fishes, spinyfins, pineconefishes, redfishes, roughies, and slimeheads. A number of member species are caught commercially, including the alfonsino, the splendid alfonsino, and the orange roughy, the latter being much more economically important. Some species have bioluminescent bacteria contained in pockets of skin or in light organs near the eyes, including the anomalopids and monocentrids.

<span class="mw-page-title-main">Holocentridae</span> Family of fishes

Holocentridae is a family of ray-finned fish, the only family of the order Holocentriformes. The members of the subfamily Holocentrinae are typically known as squirrelfish, while the members of Myripristinae typically are known as soldierfish. In Hawaii, they are known by the Japanese name mempachi/menpachi (メンパチ) or the Hawaiian ʻūʻū.

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<span class="mw-page-title-main">Hong Kong grouper</span> Species of fish

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<span class="mw-page-title-main">Camouflage grouper</span> Species of fish

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<i>Serranus tigrinus</i> Species of fish

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<i>Plectropomus laevis</i> Species of fish

Plectropomus laevis, known commonly as the black-saddled coral grouper, cluespotted coral trout, blacksaddled coral trout, blue-spot trout, Chinese footballer, footballer cod, footballer coral trout, oceanic coral trout or tiger trout, is a species of marine ray-finned fish, a grouper from the subfamily Epinephelinae which is part of the family Serranidae, which also includes the anthias and sea basses. It is found in the Indo-Pacific region.

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<span class="mw-page-title-main">Splitfin flashlightfish</span> Species of fish

The splitfin flashlightfish or two-fin flashlightfish is a species of beryciform fish in the family Anomalopidae. It is found in warm waters in the central and western Pacific Ocean near shallow reefs 200–400 m (660–1,300 ft) in depth. It can grow to a length of 35 cm (14 in) TL. It is the only known member of its genus.

The Atlantic flashlightfish is a species of flashlight fish native to the western Atlantic Ocean. During the day, it is found in waters as deep as 200 metres (660 ft). On moonless nights, it ascends to shallow waters around 25 metres (82 ft) in depth where it feeds on small shrimp and copepods as it swims over the ocean floor. This species grows to a length of 12.5 centimetres (4.9 in) TL. This species is the only known member of its genus and can be found in the aquarium trade.

Photoblepharon is a genus of poorly understood flashlight fishes found around reefs in the western Pacific Ocean (P. palpebratum) and in the western Indian Ocean (P. steinitzi). Both of its species are nocturnal predators, hiding in caves and crevices during the day and emerging at night to feed. They are small fish, 11.0–12.0 cm (4.3–4.7 in) maximum length, and of little commercial value, although fishermen have been known to use their light organs as bait. Like other anomalopids, they are notable for the white organs containing bioluminescent bacteria underneath their eyes, which, by emitting a blue-green light, allow the fish to search for food, evade predators, and communicate with other fish. Both species have black lids that slide up to cover the organ when the fish does not want to emit light. Although similar in appearance, they can be easily distinguished by the preopercle, which has a medium-sized white spot in P. palpebratum, whereas in P. steinitzi, it is much smaller and much darker, or not present at all. Neither species has been evaluated by the International Union for Conservation of Nature (IUCN) and their nocturnal natures make collection difficult and sightings uncommon.

The Gulf flashlightfish is a species of saltwater fish of the family Anomalopidae, also known as lanterneye fish, of the order Beryciformes. It is endemic to the Gulf of California. This cryptic fish is the only known member of its genus. It was first reported in the Pacific Ocean in 1976 and is extremely rare.

Flashlight fish is a common name for several fish and may refer to:

Parmops coruscans is a species of flashlight fish, order Beryciformes, native to the Pacific Ocean off the coast of Tahiti and from Fiji to French Polynesia. It is one of two species of Parmops along with P. echinatus, which was discovered off the coast of Fiji. Like other anomalopids, it is notable for the light organs underneath its eyes, which contain bioluminescent bacteria. To cover the organs, it rotates them down while sliding a black lid upward over each eye. The lack of development in its shutter mechanism helps place it between Anomalops and Phthanophaneron on the evolutionary tree.

The flashlight fish is a species of anomalopid fish of the order Beryciformes. It is native to the western Indian Ocean and the Red Sea where it is found near coral reefs. It is a nocturnal predator, hiding in crevices and caves by day and emerging to feed at night. At 11.0 cm (4.3 in) in length, it is small and relatively stout. Its body is mostly solid black, with the exception of white discoloration around its pectoral fins and a lateral line of reflective scales. It is most notable for the bioluminescent organs located underneath its eyes, which it uses to find prey, evade predators, and communicate with other members of its species. Like other Beryciformes, its reproduction is oviparous. It has no commercial value, and this combined with its timid, nocturnal nature makes population sizes and trends unknown. It is listed as Least Concern by the International Union for Conservation of Nature (IUCN) due to a wide distribution and lack of known threats.

Protoblepharon rosenblatti, the Cook Islands flashlightfish, is a species of flashlight fish found in the waters surrounding the Cook Islands. It can reach lengths of up to 22.0 cm (9 in) and can be found as deep as 274 m (900 ft).

References

  1. 1 2 Moore, J. (2020). "Photoblepharon palpebratum". IUCN Red List of Threatened Species . 2020: e.T123356060A123356182. doi: 10.2305/IUCN.UK.2020-1.RLTS.T123356060A123356182.en . Retrieved 20 November 2021.
  2. 1 2 3 4 5 6 7 8 Froese, Rainer; Pauly, Daniel (eds.) (2017). "Photoblepharon palpebratum" in FishBase. January 2017 version.
  3. ↑ Boddaert, Peter (1781). "Beschreibung zweier merkwürdiger Fische". Neue Nordische Beyträge zur Physikalischen und Geographischen Erd- und Völkerbeschreibung, Naturgeschichte und Oekonomie. 2: 55–57. doi:10.5962/bhl.title.48400. ISBN   0665382766.
  4. 1 2 3 McCosker, John E.; et al. (1987). "Notes on the Biology, Taxonomy, and Distribution of Flashlight Fishes (Beryciformes: Anomalopidae)". Japanese Journal of Ichthyology. 34 (2): 157–164. doi:10.1007/BF02912410. S2CID   81261778.
  5. 1 2 3 4 5 Johnson, G. David; et al. (1988). "Mechanisms of light organ occlusion in flashlight fishes, family Anomalopidae (Teleostei:Beryciformes), and the evolution of the group". Zoological Journal of the Linnean Society. 94: 65–96. doi:10.1111/j.1096-3642.1988.tb00882.x.
  6. ↑ Bray, Dianne J. "Onefin Flashlightfish, Photoblepharon palpebratum (Boddaert 1781)". Fishes of Australia. Museums Victoria. Retrieved 3 January 2017.
  7. ↑ Haneda, Yata; et al. (1971). "Light Production in the Luminous Fishes Photoblepharon and Anomalops from the Banda Islands". Science. 173 (3992): 143–145. doi:10.1126/science.173.3992.143. PMID   5581906. S2CID   1233880.
  8. ↑ "Photoblepharon palpebratum". eol.org. Encyclopedia of Life. Retrieved 8 January 2017.
  9. ↑ Morin, James G.; et al. (1975). "Light for All Reasons: Versatility in the Behavioral Repertoire of the Flashlight Fish". Science. 190 (4209): 74–76. doi:10.1126/science.190.4209.74. S2CID   83905458.
  10. ↑ Meyer-Rochow, V. B. (1976). "Some Observations on Spawning and Fecundity in the Luminescent Fish Photoblepharon palpebratus". Marine Biology. 37 (4): 325–328. doi:10.1007/BF00387487. S2CID   84779819.
  11. ↑ Wolfe, Connie J.; et al. (1991). "Restriction Fragment Length Polymorphism Analysis Reveals High Levels of Genetic Divergence among the Light Organ Symbionts of Flashlight Fish". Biological Bulletin. 181 (1): 135–143. doi:10.2307/1542496. JSTOR   1542496. PMID   29303659.
  12. ↑ Haygood, M. G.; et al. (1984). "Luminous bacteria of a monocentrid fish (Monocentris japonicus) and two anomalopid fishes (Photoblepharon palpebratus and Kryptophanaron alfredi): population sizes and growth within the light organs, and rates of release into the seawater". Marine Biology. 78 (3): 249–254. doi:10.1007/bf00393010. S2CID   84148478.
  13. ↑ Harvey, E. Newton (1922). "The production of light by the fishes Photoblepharon and Anomalops". Carnegie Institute Washington D.C. Publication. 312: 45–60.
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