Benutzer:Regiomontanus/Bearbeitete Artikel/Bolitaenidae

Bolitaenidae
	Bolitaena pygmaea, juveniles Weibchen
Systematik
Stamm:	Weichtiere (Mollusca)
Klasse:	Kopffüßer (Cephalopoda)
Unterklasse:	Tintenfische (Coleoidea)
Überordnung:	Achtarmige Tintenfische (Vampyropoda)
Ordnung:	Kraken (Octopoda)
Familie:	Bolitaenidae
Wissenschaftlicher Name
	Bolitaenidae
	(Chun, 1911

Die Bolitaenidae bilden eine Familie der Kraken innerhalb der Achtarmigen Tintenfische (Vampyropoda). Die Taxonomie der Familie ist nicht endgültig geklärt, sie umfasst mindestens zwei verschiedene Gattungen, Bolitaena und Japetella. Es wurden immer wieder neue Arten beschrieben, vielfach handelt es sich dabei aber um verschiedene Jungstadien der beiden Arten Bolitaena pygmaea and Japetella diaphana.

Merkmale

Die Arten der Familie Bolitaenidae werden nicht länger als rund 8,5 cm Mantellänge bzw. 12 cm Gesamtlänge. Daraus folgt, dass ihre Arme im Verhältnis zum Körper relativ kurz sind, anders als bei den meisten anderen Familien der Kopffüßer. Die Arme besitzen nur je eine Reihe von Saugnäpfen. Die adulten Männchen unterscheiden sich von den Weibchen durch ihre vergrößerten Saugnäpfe auf dem dritten Arm rechts. Bei Bolitaena pygmaea trägt dieser Arm auch den Hectocotylus, einen Anhang zur Übergabe der Spermatophoren während der Begattung

Perhaps the most striking feature of the family is seen in mature females; upon maturity a ring-shaped Photophor—a light-producing organ—develops to encircle the mouth. This is believed to be an adaptation to life in gloomy, deep ocean waters; the bioluminescent ring may help males and females to find each other.

The eyes of both species are laterally compressed; they are distinctly smaller and set farther apart from the brain on longer optic stalks in Bolitaena than in Japetella—this feature may be the only way to differentiate the two genera when examining subadults. Mature males are rarely encountered. Their translucent, gelatinous bodies are fragile and easily damaged during collection.

Habitat

Mature bolitaenids occupy depths in the meso- to bathypelagic zones of the water column, down to about 1,425 metres. Younger animals (under 20 millimetres mantle length) are known to remain in shallower waters, either from 170-270 metres or 500-800 metres depending on size. Japetella is known to venture into far northern waters.

Fortpflanzung

Mating is thought to occur at or below 1,000 metres depth. In the darkness, whether mating is successful or not may depend on the female; she can choose whether to signal the male with her circumoral photophore. The light emitted by the photophore is believed to be of a specific wavelength, possibly both preventing miscommunication and the attraction of predators.

After mating the female then rises to about 800 metres to brood. Her eggs are interconnected by a number of stalks; the whole mass is held safely by means of suckers near her mouth. Due to the cold (4–5°) environment, brooding likely takes several months; the female is thought to forgo food during this entire period. After hatching, the young octopuses rise to the productive, upper 300 metres of the water column where they remain until reaching a certain size (7–20 millimetres). As they mature the young begin their gradual descent to the mesopelagic and eventually bathypelagic zones.

Weblinks

Wikibooks: Bolitaenidae – Lern- und Lehrmaterialien

Tree of Life Web: Bolitaenidae

[[Kategorie:Kopffüßer]] [[Kategorie:Cephalopoda]]