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Benthosema pterotumOpaline lanternfish(Also: Skinnycheek lanternfish; Spinycheek lanternfish)

By Sarah Sabbagh

Geographic Range

Skinnycheek lanternfish (Benthosema pterotum) are myctophid fish that are abundant in the coastal waters of the Indian and Pacific Oceans. Specifically, their range extends along the African coast from southern Mozambique and follows the coast northward to the Arabian Sea and the Gulf of Aden. Their range includes the southern coast of the Arabian Peninsula and continues westward through the Gulf of Oman, along the coasts of Pakistan and India. Their continuous range extends eastward through the Bay of Bengal and includes the waters around the Philippines, Indonesia, the Koreas, and Japan. From there, the range includes the northern coast of southern Russia. From Indonesia, these lanternfish inhabit the waters around Papua New Guinea, continuing southward to the western Australian coast. The species is prevalent in the East China Sea, the tropic zones of the Indian Ocean, the north Arabian Sea, the Red Sea, and into the Gulf of Oman. (Catul, et al., 2011; Gj∅saeter, 1984; Paxton, 2010; Sassa, et al., 2010)

Habitat

Skinnycheek lanternfish are oceanic fish that are found in both pelagic and coastal regions. Like other members of the same family, these lanternfish thrive in poorly oxygenated waters. One adaptation that allows lanternfish to survive low-oxygen zones is the performance of diel vertical migration (DVM). Lanternfish migrate upwards into the epipelagic zone during the night and back downwards into the mesopelagic zone during the day. This way, they travel to nutrient-high waters while maintaining a lower metabolic rate. The range of this migration, including both zones, is 10m-2000m in myctophid fish. During the day, skinnycheek lanternfish forage between the depths of 200m-400m. (Catul, et al., 2011; Dalpadado and Gjøsæter, 1988)

  • Range depth
    10 to 2000 m
    32.81 to 6561.68 ft

Physical Description

Myctophids have a distinguishing adaptation in the form of photophore organs. Through oxidation and enzymatic activity, these organs produce and manipulate the intensity of blue, green, and yellow-colored light that camouflage fish from predators and improve sight in the dark. The photophores line the ventral side of lanternfish with patterns that are unique to each species of lanternfish. With round heads, lanternfish have thin bodies that can reach 70 mm long. Females tend to be notably larger than males. Sassa et al. (2014) reported that in a sample of >3000 specimens, the range in standard length was 10.7–54.8 mm, but no males were greater than 46 mm in length.

The average body mass of skinnycheek lanternfish is 0.25g, and the average length is 19.4 mm. Their mouths extend beyond their large, round eyes. Melanophores encasing melanin provide pigment in areas on the body including the snout, jaw, and gut. They are equipped with a set of fins including a caudal fin, a pair of pectoral fins, a pelvic fin, an anal fin, and an adipose fin. The dorsal fin has 13-14 soft rays, while the anal fin has 17-22.

Eggs are around 0.80 mm in diameter. After hatching, larvae more than double their size and can reach 2 mm. Most hatch at 1.4-1.6 mm in length. (Catul, et al., 2011; Dalpadado and Gjøsæter, 1988; Dypvik and Kaartvedt, 2013; Froese and Pauly, 2021; Olivar, et al., 1999; Sassa, et al., 2014)

  • Sexual Dimorphism
  • female larger
  • Average mass
    0.25 g
    0.01 oz
  • Range length
    10.7 to 54.8 mm
    0.42 to 2.16 in
  • Average length
    19.4 mm
    0.76 in

Development

Skinnycheek lanternfish, like all fish, exhibit indeterminate growth. Colder environments may delay hatching and development for members of this family, but lower salinity may allow for faster development. It is suspected that skinnycheek lanternfish follow the same developmental trends. Generation length is reported as 0.5 years.

Skinnycheek lanternfish hatch when they are around 1.4-1.6 mm. At hatching, larvae lack eyes and pigmentation. As they develop, skinnycheek lanternfish undergo changes in pigmentation. Melanophores around the jaw and gut disappear when the fish grows larger than 10mm. Stages of development have not been fully described for skinnycheek lanternfish. However, Sassa et al. (2015) reported larval growth rates of 0.26 mm per day for length and increases in mass of 18.8% of their body mass per day. This is a relatively high growth rate as compared to other species in the family, and the authors attributed these rates to plentiful food sources.

Sassa et al. (2015) also reported clusters of larvae at depths of 60-80m below the surface. Juveniles can inhabit depths closer to the surface because of the buoyancy their swim bladders provide. (Catul, et al., 2011; Dalpadado, 1988; Dypvik and Kaartvedt, 2013; Gilles and Payan, 2001; Gjøsæter and Tilseth, 1988; Nafpaktitis, et al., 1977; Olivar, et al., 1999; Paxton, 2010; Sassa, et al., 2015; Wang and Lee, 2020)

Reproduction

Mating systems are not well studied for skinnycheek lanternfish. Females release their eggs and don’t show any guarding behavior. The males externally fertilize the eggs afterward. This suggests a polygynandrous mating system, as no pair-bonds form.

Sassa et al. (2015) examined patterns in larval presence and growth in the East China Sea, where these lanternfish are common. They suggested that skinnycheek lanternfish spawn twice in the late summer/early fall months, approximately once a month apart, and that spawning is driven by moon phases. Spawning likely coincided with a new moon phase. (Gjøsæter and Kawaguchi, 1980; Sassa, et al., 2015)

Sassa et al. (2015) studied skinnycheek lanternfish in the East China Sea and reported that these fish may spawn twice in the autumn months, about a month between events. They suggested that spawning coincided with the new moon. It is also reported that spawning occurs at dusk. Fertilization is external. Because eggs and newly-hatched larvae have been found at depths of 200-300m below the surface, it is thought that spawning occurs here, as well.

Dates of hatching were noted in two bouts: one from late August until early September, and another from mid-September until late September. Time to hatching is about 12 hours when the water temperature is 21°C. Hatching can occur at 200 m, but certainly before they rise in the column (the eggs are buoyant) to within 50 m of the surface. Independence is immediate, as these fish provide no parental care for the fertilized eggs.

The number of eggs per spawning event is unrecorded, but females examined during the spawning season held 253-1942 eggs; the number of eggs per female was greater with greater total lengths (Sassa et al. 2014).

Sassa et al. (2014) reported maturity measures by length. They found that females reach maturity at body lengths at 28 mm and males do so at 24 mm standard length. Generation length is reported as 0.5 years; this may be age at sexual maturity, but these fish only reproduce in August-September of each year. (Gjøsæter and Tilseth, 1988; Paxton, 2010; Sassa, et al., 2014; Sassa, et al., 2015)

  • Breeding interval
    Breed twice, one month apart, in the autumn months
  • Breeding season
    August - September in line with the new moon, at dusk
  • Range number of offspring
    253 to 1942
  • Average time to hatching
    12 hours
  • Average time to independence
    0 minutes
  • Average age at sexual or reproductive maturity (female)
    0.5 years
  • Average age at sexual or reproductive maturity (male)
    0.5 years

Beyond mating, there is not any parental investment by skinnycheek lanternfish. They young are independent upon hatching. (Gjøsæter and Kawaguchi, 1980)

  • Parental Investment
  • no parental involvement

Lifespan/Longevity

Myctophids tend to live for 1-5 years, a shorter lifespan than that of Glacier lanternfish Benthosema glaciale (8 years). Mortality rates are high in myctophids, especially right after hatching. Sassa et al. (2015) reported that in the first 14 d post-hatching, the rate of mortality was 24.7% per day. Salinity also impacts the mortality rates of myctophid larvae. Skinnycheek lanternfish have larvae that require high levels of salinity. These lanternfish have to eat more frequently to survive low levels of salinity.

The concentration of dissolved oxygen in water also impacts the mortality rate for myctophids. Similar to low temperatures, low oxygen levels decrease the rate of metabolism. A rise in oxygen levels leads to increased metabolic activity and a shorter lifespan. In contrast, lanternfish larvae tend to survive better in higher temperatures (around 24 °C). The optimum habitat for skinnycheek lanternfish is low temperatures in deep waters.

Skinnycheek lanternfish are not kept in captivity. (Catul, et al., 2011; Froese and Pauly, 2021; Sassa, et al., 2015; Wang and Lee, 2020)

  • Typical lifespan
    Status: wild
    1 to 5 years

Behavior

Skinnycheek lanternfish perform vertical migration together, as echosounder records show, in densely packed groups an hour before the sun sets. Their journey to the epipelagic zone is complete an hour after sunset. This suggests major crepuscular movements. This movement allows nutrients to drift between the mesopelagic zones and epipelagic zones. Normal diel vertical migrations (NDVM) provide the lanternfish with refuge from predators that reside in the depths. Additionally, the lanternfish feed on the abundance of zooplankton and crustaceans in the epipelagic zone after migrating. Skinnycheek lanternfish densely pack together for safety reasons and to benefit from group hunting.

Photophores aid in lanternfish sight and communication with potential mates. (Bleckmann and Zelick, 2009; Catul, et al., 2011; Dypvik and Kaartvedt, 2013)

Home Range

While skinnycheek lanternfish do perform diel vertical migration, the volume they encompass has not been quantified. They also do not defend a territory nor do they maintain a specific home range.

Communication and Perception

Photophores aid lanternfish in improving sight and gaining attention from potential mates. Photophore arrangements vary based on lanternfish species and sex, allowing for communication between males and females. Skinnycheek lanternfish densely pack together for safety reasons and to benefit from group hunting. Their nervous system is also connected to a lateral line system that runs through the length of the fish and sends impulses to the brain. This system has many purposes such as pressure perception and detection of objects (predators, prey) in their surroundings.

Like most fish, they use tactile senses to feed and to spawn. Their chemical communication and use of pheromones have not been studied. (Bleckmann and Zelick, 2009; Catul, et al., 2011)

Food Habits

Myctophids feed on various types of zooplankton organisms, which they normally do during the nighttime. Though skinnycheek lanternfish occasionally feed during the day, they typically forage at night. Vertical diel migration is essential in allowing myctophids to locate prey such as krill, copepods, and fish eggs in the epipelagic layer. Skinnycheek lanternfish feed on many different kinds of shrimp and other crustaceans, and they don’t typically eat more food than one-third of their body weight.

With the ability to make up over half of their diet, copepods are the most common food item for this species. Hobano et al. (2021) investigated the feeding habits of skinnycheek lanternfish along the coast of Japan. During April (spring) and July (summer) surveys, they found that these fish consumed primarily copepods during morning and evening hours with those in the genus Oncae comprising as much as a third of all items. They occasionally consumed amphipods, mysids (opossum shrimp), and ostracods in small (less than 3%) proportions. (Catul, et al., 2011; Dalpadado and Gjøsæter, 1988; Dypvik and Kaartvedt, 2013; Habano, et al., 2021)

  • Animal Foods
  • fish
  • eggs
  • aquatic crustaceans
  • zooplankton

Predation

In the Arabian Sea, predators such as Alcock's boafish (Stomias nebulosus), Sloane's viperfish (Chauliodus sloani), and viperfish lacking a common name (Chauliodus pammelas) are known to prey on myctophids primarily. Additional predators include penguins, non-mesopelagic fish, and other lanternfish in Family Myctophidae.

In search of zooplankton, skinnycheek lanternfish are able to hide from predators while migrating vertically. They are able to camouflage themselves and appearing as a mere shadow. (Butler, et al., 2001; Catul, et al., 2011)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Skinnycheek lanternfish consume zooplankton and crustaceans. Their predators include viperfish, penguins, non-mesopelagic fish, and other lanternfish.

Parasites such as copepods (Cardiodectes medusaeus) and nematode larvae use myctophids as hosts.

Lanternfish maintain an important position in the food web between primary and tertiary consumers. Their predators derive a lot of energy from consuming them due to their high lipid content. Skinnycheek lanternfish also make a contribution to their ecosystem by dropping their waste. Simply by dying and decomposing, lanternfish improve the nutrient flow in the benthic zone. Through diel vertical migration, lanternfish act as vessels transporting carbon from the surface layer to deeper waters. (Catul, et al., 2011; Dalpadado and Gjøsæter, 1988)

Commensal/Parasitic Species

Economic Importance for Humans: Positive

Skinnycheek lanternfish are rich in nutrients, making them suitable for animal feed, poultry feed, crop fertilizer, and potential use in the fishmeal industry. In general, myctophids require processing before being served to people. They are not often used for human consumption due to their high content of wax esters. (Catul, et al., 2011)

  • Positive Impacts
  • food

Economic Importance for Humans: Negative

There are no known adverse economic effects of skinnycheek lanternfish on humans.

Conservation Status

Skinnycheek lanternfish are listed as a species of "Least Concern" on the IUCN Red List. They have no special status on the US federal list, CITES, or the state of Michigan list.

Trawling has the potential to threaten this species, particularly the larvae and juveniles because they are captured most easily. They have been suggested as a source for fish meal. By eliminating this benthic species, the commercial use of myctophids can permanently alter the organization of the food web. The low fecundity rate of myctophids suggests that commercial fishing may have a substantial impact.

There are no known conservation efforts to try and protect this species beyond researchers attempting to quantify the harvesting of skinnycheek lanternfish. However, trawling efforts to capture these lanternfish are not deemed economically viable. (Catul, et al., 2011; Paxton, 2010)

Contributors

Sarah Sabbagh (author), Radford University, Karen Powers (editor), Radford University, Victoria Raulerson (editor), Radford University, Christopher Wozniak (editor), Radford University, Genevieve Barnett (editor), Colorado State University.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

crepuscular

active at dawn and dusk

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diurnal
  1. active during the day, 2. lasting for one day.
ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body

fertilization

union of egg and spermatozoan

food

A substance that provides both nutrients and energy to a living thing.

indeterminate growth

Animals with indeterminate growth continue to grow throughout their lives.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

migratory

makes seasonal movements between breeding and wintering grounds

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pelagic

An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).

photic/bioluminescent

generates and uses light to communicate

piscivore

an animal that mainly eats fish

planktivore

an animal that mainly eats plankton

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

zooplankton

animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)

References

Bleckmann, H., R. Zelick. 2009. Lateral line system of fish. Integrative Zoology, 4/1: 13-25.

Butler, M., S. Bollens, B. Burkhalter, B, L. Madin, L, E. Horgan. 2001. Mesopelagic fishes of the Arabian Sea: Distribution, abundance and diet of Chauliodus pammelas, Chauliodus sloani, Stomias affinis, and Stomias nebulosus. Deep Sea Research Part II: Topical Studies in Oceanography, 48/6: 1369-1383. Accessed November 22, 2021 at 10.1016/S0967-0645(00)00143-0.

Catul, V., M. Gauns, P. Karuppasamy. 2011. A Review on Mesopelagic Fishes Belonging to Family Myctophidae. Reviews in Fish Biology and Fisheries, 21/3: 339-354.

Chiou, W., C. Chen, C. Wang, C. Chen. 2006. Food and feeding habits of ribbonfish Trichiurus lepturus in coastal waters of south-western Taiwan. Fisheries Science, 72/2: 373-381.

Dalpadado, P. 1988. Reproductive biology of the lanternfish Benthosema pterotum from the Indian Ocean. Marine Biology, 98/3: 307-316.

Dalpadado, P., J. Gjøsæter. 1988. Feeding ecology of the lanternfish Benthosema pterotum from the Indian Ocean. Marine Biology, 99/4: 555-567.

Dypvik, E., S. Kaartvedt. 2013. Vertical migration and diel feeding periodicity of the skinnycheek lanternfish (Benthosema pterotum) in the Red Sea. Oceanographic Research Papers, 72: 9-16.

Froese, R., D. Pauly. 2021. "Benthosema pterotum" (On-line). Fishbase. Accessed November 22, 2021 at https://www.fishbase.se/summary/Benthosema-pterotum.html.

Gilles, B., P. Payan. 2001. How should salinity influence fish growth. Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 130/4: 411-423.

Gjøsæter, J., S. Tilseth. 1988. Spawning behaviour, egg and larval development of the myctophid fish Benthosema pterotum. Marine Biology, 98/1: 1-6.

Gjøsæter, J., K. Kawaguchi. 1980. A Review of the World Resources of Mesopelagic Fish. Rome, Italy: Food and Agriculture Organization of the United Nations.

Gj∅saeter, J. 1984. Mesopelagic fish, a large potential resource in the Arabian Sea. Oceanographic Research Papers, 31/6: 1019-1035.

Habano, A., T. Kobari, W. Ohbayashi, G. Kume. 2021. Feeding habits of the skinnycheek lanternfish [Benthosema pterotum (Alcock, 1890)] in Kagoshima Bay, southern Japan. Ichthyological Research, 68/1: 164-170.

Hosseini-Shekarabi, S., T. Valinassab, Z. Bystydzienska, T. Linkowski. 2015. Age and growth of Benthosema pterotum (Alcock, 1890) (Myctophidae) in the Oman Sea. Journal of Applied Ichythyology, 31/3: 51-56.

Nafpaktitis, B., R. Backus, J. Craddock, R. Haedrich, B. Robison. 1977. Fishes of The Western North Atlantic. Lawrence, Kansas: Allen Press.

Olivar, M., H. Moser, L. Beckley. 1999. Lanternfish larvae from the Agulhas current (SW Indian Ocean). Scientia Marina, 63/2: 101-120.

Paxton, J. 2010. "Benthosema pterotum" (On-line). The IUCN Red List of Threatened Species 2010: e.T155260A4759559. Accessed September 07, 2021 at https://dx.doi.org/10.2305/IUCN.UK.2010-4.RLTS.T155260A4759559.en.

Sassa, C., M. Takahashi, Y. Tsukamoto. 2015. Distribution, hatch-date, growth, and mortality of larval Benthosema pterotum (Pisces: Myctophidae) in the shelf region of the East China Sea. Journal of the Marine Biological Association of the United Kingdom, 95/1: 161-174.

Sassa, C. 2019. Estimation of the spawning biomass of myctophids based on larval production and reproductive parameters: The case study of Benthosema pterotum in the East China Sea. ICES Journal of Marine Science, 76/3: 743-754.

Sassa, C., O. Seiji, T. Hiroshige, T. Youichi. 2014. Reproductive biology of Benthosema pterotum (Teleostei: Myctophidae) in theshelf region of the East China Sea. Journal of the Marine Biological Association of the United Kingdom, 94/2: 423-433.

Sassa, C., Y. Tsukamoto, K. Yamamoto, M. Tokimura. 2010. Spatio-temporal distribution and biomass of Benthosema pterotum (Pisces: Myctophidae) in the shelf region of the East China Sea. Marine Ecology Progress Series, 407: 227-241.

Valinassab, T., P. Hosseini Shekarabi. 2011. Growth pattern and daily growth increment in lanternfish (Benthosema pterotum) of the Oman Sea. Iranian Scientific Fisheries Journal, 20: 147-160.

Valinassab, T., G. Pierce, K. Johannesson. 2007. Lantern fish (Benthosema pterotum) resources as a target for commercial exploitation in the Oman Sea. Journal of Applied Ichthyology, 23/5: 573-577.

Wang, Y., M. Lee. 2020. Ontogenetic habitat differences in Benthosema pterotum during summer in the shelf region of the southern East China Sea. Deep Sea Research Part II Topical Studies in Oceanography, 175: 104739. Accessed November 22, 2021 at https://doi.org/10.1016/j.dsr2.2020.104739.

Zhang, H., L. Lin. 2005. Spatial heterogeneity of Trichiurus japonicus and small-scale fish in East China Sea and their spatial relationships. The Journal of Applied Ecology, 16/4: 708-711.

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