Graneledone antarctica
| Graneledone antarctica | ||||||||||||
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| Scientific name | ||||||||||||
| Graneledone antarctica | ||||||||||||
| Voss , 1976 |
Graneledone antarctica is a large cephalopod in the genus Graneledone . It lives in the southern ocean , the Ross Sea, and the Antarctic .
features
anatomy
Graneledone antarctica reaches a total length of 208 millimeters. The coat becomes up to 45 millimeters long, whereby the size varies. The females are usually larger than the males. The mantle is short, clearly rounded towards the back, very broad and is clearly flattened dorsoventrally . The head is separated from the coat by a slight narrowing and at 40 millimeters is almost as wide as the coat. He is flattened and has big, striking eyes.
The tentacles are of different lengths and relatively thick. They are up to 165 millimeters long. As a rule, the first or second pair of arms is always the longest and the fourth pair is always the shortest. In male Graneledons antarctica , the third right arm forms the Hectocotylus . It is framed ventrally by a membrane-like tissue. The outer edge is thickened, cream colored and rolled outwards. At the top there is a small ligula that can be up to 4.5 millimeters long. It is spoon-shaped and has thickened edges. The ligula is pointed distally . The calamus, up to 2 millimeters in size, protrudes, low and blunt. Graneledone antarctica has 1 row of suction cups on each tentacle . They are largest at the base of the arm and decrease at regular intervals to the tip of the arm. They reach a diameter of 3.3 millimeters.
The velar skin is only moderately developed. But there are individual variations. On the dorsal side of the arms, it only extends over a small area on each tentacle. On the ventral side of the first three pairs of arms, it extends to the tip of the arms, with only the tip exposed. It is narrow in the basal half of the tentacles. The velar skin expands from the middle of the arms and becomes widest at the distal fifth of the tentacles.
The throat is traversed by 12–13 deep, fleshy folds. Inside is a sharp beak. The radula has no edge plates and a different number of radular teeth in specimens of the same species. These can differ in appearance and their arrangement. The buccal mass is large. The anterior, comparatively large salivary glands are embedded in it. The rear pair of salivary glands is very small and poorly developed. The esophagus leads from the buccal mass posteriorly to a goiter without a diverticulum . The gills have six lamellae per demibranch. The funnel organ is VV-shaped, but shows considerable differences. It is composed of two elongated, oval balls, which are equipped with a few pointed or blunt spines on the front. The front half is exposed and has a conical, tubular shape. The stomach is of moderate size and divided into two parts. One part has a thin stomach wall and the other part is muscular and thick-walled. The spiral-shaped appendix is small, thick, smooth on the outside, and connected to the small heart-shaped liver by paired hepatopancreatic ducts. The intestine is thick and thin-walled. There are no anal valves.
Appearance
Descriptions of the skin color of Graneledone antarctica are based on dead animals soaked in alcohol. The specimens had a pale, yellowish-brown skin surface with purple shades at the base of the brute crown and the arms. Based on this basic color, there are red-brown to purple areas on the coat, head, arm bases and funnel organ. Graneledone antarctica has a yellowish spermatophoric groove.
There is a distinct line of fine warts on the periphery of the mantle. These are arranged in the form of a keel that runs from the corners of the jacket opening around the jacket to the rear. There are no warts under the arrangement, and the surface is smooth. There is a distinct wart ring on the eyelids. These are slightly larger than the other warts, and two or three of them above each eye are greatly enlarged and, although not erect, likely represent ocular cirrus .
habitat
The habitat of Graneledone antarctica are the coastal waters of the Antarctic , the southern ocean and the Ross Sea . The species lives at depths of up to 2341 meters.
research
The contraction of the thickened edge of the hectocotylus curls the tip of the arm in preserved animals downwards and resembles a hook or a slight S-curve. This form is unlikely to occur in live animals, but is due to the effects of the preservative.
The goiter was opened in a dissected specimen of the Graneledone antarctica . It contained an amorphous mass of animal tissue in which numerous polychaeta bristles were embedded.