Lanternfish

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Lanternfish
Slender-tailed lanternfish (Myctophum punctatum)

Slender- tailed lanternfish ( Myctophum punctatum )

Systematics
Subclass : Real bony fish (Teleostei)
Overcohort : Clupeocephala
Cohort : Euteleosteomorpha
Sub-cohort : Neoteleostei
Order : Lanternfish (Myctophiformes)
Family : Lanternfish
Scientific name
Myctophidae
Gill , 1893

The lantern fish (Myctophidae) are a species and individual rich family of small deep sea fish . Its sister family, the lantern beak (Neoscopelidae), is much poorer in species. Lanternfish live in all oceans. They got their name because of their luminous organs.

Lantern fish , together with the bristle mouths (Gonostomatidae) and the luminous fish (Phosichthyidae) make up 90% of the live mass of all deep-sea fish. Their total live mass is estimated at 550–660 million tons. Adult lantern fish make up 65% of all fish in the mesopelagial , when plankton is caught , the larvae of the lantern fish make up 50% of all fish larvae.

Lanternfish are fished commercially in South Africa, sub-Antarctic waters and the Gulf of Oman .

Appearance

Anatomy of the lantern fish using the example of Lampanyctodes hectoris ((1) - gill cover, (2) - lateral line, (3) - dorsal fin, (4) - adipose fin, (5) - caudal stalk, (6) - caudal fin, (7) - anal fin , (8) - luminous organs, (9) - pelvic fins (paired), (10) - pectoral fins (paired))
Distribution of the luminous organs using the example of Hygophum hygomii

Lanternfish have a small, slender body covered by small cycloid scales, a relatively large, round head, and a large mouth.

The animals have a single high dorsal fin and an adipose fin, the caudal fin is forked. The pectoral fins usually have eight rays. They can be large or small or degenerate, in some species they are completely absent.

Most lanternfish have a swim bladder . In some species it is regressed or filled with lipids during growth . The sideline is continuous.

All species, with the exception of Taaningichthys paurolychnus , have luminous organs emitting blue, green or yellow light in rows along the body and on the head. In the genus Diaphus z. B. There are headlight-like light organs near the eyes. Some species also have luminous organs on the underside of the fins. Sometimes the sexes also differ in the arrangement of the light organs. It is assumed that the luminous organs play a role in attracting partners and in keeping the swarm together.

ecology

Lanternfish make a vertical migration . During the day, most species stay in the dark bathypelagic zone at depths of 300 to 1200 meters. At sunset, the animals begin to rise to 10 to 100 meters. They follow the migration of the zooplankton on which they feed. At daybreak they swim back into the depths. The different species are at different depths. There can also be different vertical migration depending on age, gender, season or the latitude of the habitat.

Most of the species stay close to the coast and can be found above the continental slopes.

The shoals of lantern fish can be seen on echo sounder images and used to be a source of confusion among oceanographers who thought they were the seabed.

Lanternfish are an important source of food for squids , other deep-sea fish , large pelagic fish such as tuna and sharks , sea birds, penguins , whales and dolphins .

Reproduction

Lanternfish larva

Lanternfish spawn pelagic in open water. The small eggs (0.70-0.90 millimeters in diameter) are held in suspension by a droplet of oil. Eggs and the two millimeter larvae float with the current. Lantern fish larvae live in shallower water than the adult animals.

Smaller species like Diogenichthys laternatus double their population within 15 months. Larger species need up to five years for this. Benthosema glaciale , a larger species, does not reach sexual maturity until 2-3 years and can live up to eight years.

Systematics

There are five subfamilies, 34 genera and about 250 species:

In the species of the subfamily Myctophinae, the luminous organs on the caudal peduncle are predominantly dimorphic . They have firmer bodies, a rounded, smooth head profile, shorter jaws, large eyes and mostly live in not as deep water layers as the species of the other subfamily. In the species of the other subfamilies, the luminous organs on the tail stalk are predominantly monomorphic. They usually live deeper than the species of the subfamily Myctophinae, have longer jaws and slacker bodies.

Diaphus adenomus
Diaphus coeruleus
Diaphus dumerilii
Diaphus effulgens
Diaphus fulgens
Diaphus lucidus
Diaphus rafinesquii
Diaphus splendidus
Diaphus termophilus
Diaphus theta

literature

  • John SS Denton: Seven-locus molecular phylogeny of Myctophiformes (Teleostei; Scopelomorpha) highlights the utility of the order for studies of deep-sea evolution. Molecular Phylogenetics and Evolution, February 2014, doi: 10.1016 / j.ympev.2014.02.009 .
  • Kurt Fiedler: Textbook of Special Zoology, Volume II, Part 2: Fish , Gustav Fischer Verlag, Jena, 1991, ISBN 3-334-00339-6 .
  • Joseph S. Nelson : Fishes of the World , John Wiley & Sons, 2006, ISBN 0-471-25031-7 .
  • Motoomi Yamaguchi: Phylogenetic analyzes of myctophid fishes using morphological characters. Japanese Journal of Ichthyology. Vol. 47; No. 2; Pp. 87-107; (2000), doi: 10.11369 / jji1950.47.87 .

Individual evidence

  1. ↑ a b Rene P. Martin, Emily E.Olson, Matthew G.Girard, Leo Smith, Matthew P.Davis: Light in the Darkness: New Perspective on lanternfish Relationships and Classification Using Genomic and Morphological Data. Molecular Phylogenetics and Evolution, January 2018, doi: 10.1016 / j.ympev.2017.12.029 .
  2. ^ Denton (2014), pp. 7–8.

Web links

Commons : Lanternfish  - Collection of images, videos and audio files