Etmopterus

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Etmopterus
Etmopterus aculeatus, the type species of the genus, now a synonym of Etmopterus spinax

Etmopterus aculeatus , the type species of the genus, now a synonym of Etmopterus spinax

Systematics
Subclass : Plate gill (Elasmobranchii)
without rank: Sharks (selachii)
Superordinate : Squalomorphii
Order : Spiny dogfish (Squaliformes)
Family : Lantern Sharks (Etmopteridae)
Genre : Etmopterus
Scientific name
Etmopterus
Rafinesque , 1810

Etmopterus is the species-richest genus of the lantern sharks (Etmopteridae) and with over 40 species one of the most species-rich sharks. They occur in parts of the Atlantic , Pacific and Indian Oceans at depths of 50 to 4500 meters and mostly live on continental slopes , less often on the continental shelf or in the open ocean. They prefer tropical to temperate regions. Some species are highly endemic and have a very small range. The great black dogfish ( Etmopterus princeps ) and the small black dogfish ( E. spinax ) also occur in the deeper northern North Sea and the latter also in the Mediterranean.

features

Most Etmopterus species are less than half a meter long. The largest species, the New Zealand lantern shark ( E. baxteri ) and the southern lantern shark ( E. granulosus ) reach lengths of 75 cm. With the dwarf lantern shark ( Etmopterus perryi ), which is only 16 to 20 centimeters long and weighs around 150 grams, the smallest known species of shark belongs to Etmopterus . The body is slim to stocky and densely covered with humped or conically shaped placoid scales. Etmopterus species are blackish to brownish in color on the back and in most cases black on the ventral side. The fins are often lighter.

The head of Etmopterus pusillus

The head is flat or almost cylindrical and wider than long or as wide as long. The snout is broadly rounded or slightly tapered at the front. The injection holes are oval or slightly angled and much smaller than the eyes. Some species have a semicircular or elongated white spot on the edge of the upper eyelid. The five gill slots are about the same length. The under-standing, short, but very wide mouth does not reach under the eyes. There are labial folds and furrows . A shallow furrow runs between the upper and lower jaw. The teeth in the upper and lower jaw are clearly different. In the upper jaw they are small, with a strong, conical and straight point and one, two or more secondary points on each side. In the lower jaw, the teeth are flat and blade-like with a single point. In the upper jaw there are 18 to 38 rows of teeth, in the lower jaw there are 24 to 55. The dorsal fins are short and high. The second dorsal fin is significantly higher than the first. The distance between the two dorsal fins is greater than the width of the two dorsal fins. The spines in front of the dorsal fins are usually strong and curved. The spine of the second dorsal fin is usually much larger than that of the first dorsal fin and extends to the tip of the second dorsal fin. Like all dogfish species , the Etmopterus species lack the anal fin. Many species have very small luminous organs that are much more dense on the belly than on the back. In addition, some species have clearly visible luminous organs on the sides, on the underside of the head, on the caudal stalk and on the caudal fin. In other species these are barely visible or completely absent. Etmopterus species have 68 to 99 vertebrae, some of which are ossified. The spiral casing has 8 to 19 turns. Etmopterus species live to be 13 to 57 years old.

Way of life

Since Etmopterus species live at greater depths, little is known about their behavior and way of life. Depending on the species, they become sexually mature at the age of 5 to 8 or even 20 to 30 years. Like the other species of the dogfish-like order, they are viviparous ( ovoviviparous ). One to 21 young animals are born per litter.

Etmopterus species may hunt in small groups, which allows these very small sharks to catch prey that is too big for a single shark. This is also indicated by the strong, short jaws with cutting and dismembering teeth, which enable the animals to prey on fish and invertebrates that cannot be swallowed all at once. The light organs could then also be used to keep the groups together during hunting or other activities.

species

Etmopterus bigelowi
Striped lantern shark ( E. bullisi )
Cylindrical lantern shark ( E. carteri )
Broadbanded Lantern Shark ( E. gracilispinis )
Dwarf lantern shark ( E. perryi )
Smooth black dogfish ( E. pusillus )
Fringed-fin lantern shark ( E. schultzi )
Green lantern shark ( Etmopterus. Virens )

To Etmopterus include over 40 types:

supporting documents

  1. ↑ a b c d e David A. Ebert: Deep-sea Cartilaginous Fishes of the Indian Ocean. Volume 1 Sharks . FAO Species Catalog for Fishery Purposes No. 8, Vol. 1, ISSN 1020-8682. Page 81 and 82.
  2. ↑ Etmopterus princeps on Fishbase.org (English)
  3. ↑ Etmopterus spinax on Fishbase.org (English)
  4. ↑ Etmopterus baxteri on Fishbase.org (English)
  5. ↑ Etmopterus granulosus on Fishbase.org (English)
  6. ↑ Etmopterus perryi on Fishbase.org (English)
  7. ↑ Etmopterus on Fishbase.org (English)