Thalassocalyce inconstans

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Thalassocalyce inconstans
Systematics
Class : Tentaculata
Order : Thalassocalycida
Family : Thalassocalycidae
Genre : Thalassocalyce
Type : Thalassocalyce inconstans
Scientific name of the  order
Thalassocalycida
Madin & Harbison , 1978
Scientific name of the  family
Thalassocalycidae
Madin & Harbison , 1978
Scientific name of the  genus
Thalassocalyce
Madin & Harbison , 1978
Scientific name of the  species
Thalassocalyce inconstans
Madin & Harbison , 1978

Thalassocalyce inconstans is the only species of the order Thalassocalycida that belongs to the rib jellyfish (Ctenophora).

Thalassocalyce inconstans has an extremely fragile body, which disintegrates even when touched lightly, so that individuals are very difficult to examine intact. The way of life and behavior of this comb jellyfish can be studied by divers or remote controlled diving robots (ROV).

Species, genus, the formally assigned family Thalassocalycidae and the order itself were described in 1978 by the two marine biologists Laurence P. Madin and G. Richard Harbison of the Woods Hole Oceanographic Institution (WHOI).

features

The animals are about 15 centimeters tall and superficially resemble hydrozoa - jellyfish , which are, however, systematically classified as cnidarians (Cnidaria).

The very fragile body has an oval cross-section and is strongly compressed perpendicular to the plane of the tentacles; towards the mouth it changes into a bell shape typical of jellyfish. The slit-shaped mouth protrudes into this umbrella-like “bell” on a cone-shaped structure that externally corresponds to the manubrium of the umbrella jellyfish.

The whitish comb ribs emerging at the end remote from the mouth are relatively short; Between the individual comb platelets there is a continuous, flagellated furrow on each rib, which probably connects neighboring platelets with one another in a mechanical manner and thus contributes to the transmission of the beat signal emitted by the statocyst .

Long channels of the digestive system, the meridional channels, which are supplied by the central “stomach” or infundibulum, run under the crest ribs, which form complex patterns in thalassocalyce inconstans . They end blindly on the side facing away from the mouth, but at the end of the mouth they are connected to the paragastric canals that run past the throat in an annular canal that runs circularly around the mouth.

Unlike the other species in the class Tentaculata the two short, with spring Tentillen occupied tentacles at Thalassocalyce inconstans not own tentacles vagina at the mouth facing away from the body side but on the mouth cone. They are used together with the cavity formed by the jellyfish umbrella to catch prey.

Thalassocalyce inconstans shows bioluminescence like other comb jellyfish . The wavelength of the emitted light is 491 nanometers.

distribution and habitat

The thalassocalycida have so far been detected in the northern Pacific , the Indian Ocean , the Atlantic and the Mediterranean . They live pelagic , i.e. in the open sea water, both as plankton near the surface (young animals) and at medium depths of 200 m to 400 m ( adults ).

nutrition

The tentacles in connection with the cavity formed by the "jellyfish" umbrella are used to catch prey. If a prey comes into contact with the tentacles, the previously widely extended bell contracts and thus prevents the prey from escaping. The rapid contraction of the bell is caused by a sphincter muscle that is not known from other rib jellyfish.

Reproduction

Reproduction is exclusively sexual; as a hermaphrodite , Thalassocalyce inconstans has male and female gonads and is therefore capable of self-fertilization - whether this occurs to a large extent or whether the animals are cross-fertilized is unknown.

Tribal history

The classification of the species in the comb jellyfish system is still unclear. Preliminary findings from morphological and molecular genetic analyzes indicate a close relationship with the Lobata and Cestida species.

Individual evidence

  1. ↑ SHD Haddock & JF Case: Bioluminescence spectra of shallow and deep-sea gelatinous zooplankton: ctenophores, medusae and siphonophores. Marine Biology, 133, pp. 571-582, 1999
  2. ↑ Dhugal J. Lindsay, James C. Hunt, Jun Hashimoto, Yoshihiro Fujiwara, Katsunori Fujikura, Hiroshi Miyake, Shinji Tsuchida: Submersible observations on the deep-sea fauna of the south-west Indian Ocean: preliminary results for the mesopelagic and near- bottom communities. Journal of Deep Sea Research, 16, pp. 23-33, 2000
  3. ↑ Holly F. Swift, William M. Hamner, Bruce H. Robison, Laurence P. Madin: Feeding behavior of the ctenophore Thalassocalyce inconstans: revision of anatomy of the order Thalassocalycida. Marine Biology, 156, pp. 1049-1056, 2009 doi : 10.1007 / s00227-009-1149-6

literature

  • Laurence P. Madin & G. Richard Harbison: Thalassocalyce inconstans, new genus and species, an enigmatic ctenophore representing a new family and order , Bulletin of Marine Science, 28, 4, 1978, page 680 (first description)
  • Holly F. Swift, William M. Hamner, Bruce H. Robison, Laurence P. Madin: Feeding behavior of the ctenophore Thalassocalyce inconstans: revision of anatomy of the order Thalassocalycida. Mar. Biol., 156, 1049-1056, 2009 doi : 10.1007 / s00227-009-1149-6

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