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Description

Cirroteuthis glacialis, n.sp.

 

 

St. 182. 14. iii. 27. Schollaert Channel, Palmer Archipelago. 64° 21' 00" S, 62° 58' 00" W. 278-­500 m., mud. Large otter trawl: one ♂.

 

 

Dimensions (in mm.).

 

 

                                                                     
 

Eyes-mantle apex

 
 

78

 
 

Web, depth, in Sector A

 
 

148

 
 

,, - edge of web (between dorsal arms)

 
 

140

 
 

,, ,, ,, B

 
 

136

 
 

Interocular width

 
 

80

 
 

,, ,, ,, C

 
 

116

 
 

Body, maximum width

 
 

58

 
 

,, ,, ,, D

 
 

92

 
 

Fins, length

 
 

75

 
 

,, ,, ,, E

 
 

66

 
 

,, width

 
 

54

 
 

 
 

 
 

Arm (left), length:

 
 

 
 

 
 

 
 

1st

 
 

200

 
 

 
 

 
 

2nd

 
 

195

 
 

 
 

 
 

3rd

 
 

185

 
 

 
 

 
 

4th

 
 

175

 
 

 
 

 
 

 

 

The general appearance is characterised by the extraordinarily deep and heavy fins and the relatively short body and wide head. It is really unlike that of any known species, though in general outline it recalls C. megaptera, Verrill (Joubin, 1920)1. The arms are in the order 1, 2, 3, 4. The longest bear about seventy-four suckers. The first fourteen to seventeen suckers are very deeply sunk in the surface tissues. When sectioned they are found to be very muscular, the inferior chamber and suctorial surface being excep­tionally well developed. This fact, considered in relation to the feebleness of the suckers of some deep-water Octopods, renders the problem of the adaptation of these animals extremely baffling (v. anon).

 

The cirrhi are disposed as usual. They do not exceed about 5.5 mm. in length, and the proximal and distal ones become very minute. The web is of the pattern A, B, C, D, E. E is well under half the depth of A, a remarkable feature. The head is large, and wider than long. The eyes are 1/9 of the area of the mantle, and are thus of relatively moderate size (Robson, 1926, p. 1349). The fins are very large. Unlike such forms as C. magna and megaptera2, in which the fins are also very large, the base is nearly the widest part and is not narrow, as in those species. The striking thing about the fins is their very great depth, which is over ⅔ of the length from the eyes to the apex of the body. The surface tissues are, as usual, gelatinous, but the general consistency is firmer and more solid than usual. The head and arms and the dorsal surface of the mantle are of a fine bluish purple. The fins and under-surface of the body are more of a reddish tint. A very peculiar feature of the oral surface us that the arms and web are coloured the same purple hue, except for a circular band of paler colour about 30 mm. deep, which passes round the mouth at the level of the 14th to the 20th sucker. The oral surface of the arms (but not of the suckers, which is ochreous) preserves the purple shade3.

 

The mantle-aperture is very narrow; but it is still to some measure free of the funnel, and not in contact with it at its side. The temporary adhesion of the funnel to the mantle-rim is, however, very perfect. The surface of the funnel is excavated to receive the mantle-edge and the two elements of the locking apparatus are very well developed. The cephalic element is singularly well developed, especially laterally. In fact I know no other Octopod in which these ridges are so deeply flanged. When the latter are engaged, it seems to me that the intake of water must be entirely prevented, as the base of the funnel is so deep that there is no room for leakage at the sides. This condition is foreshadowed in Macrochlaena (Robson, 1929, p. 194). The funnel itself is well developed. It is narrowly conical in shape, and its organ is well developed (Fig. 3). It consists of a thick-limbed plate in the shape of an inverted V (Λ). The fin supports (Fig. 2) are like none so far described. As in Chunioteuthis ebersbachii and C. grimaldii and umbellata, the “arms” of the supports are long. The apical part is angular (rather as in C. meangensis) and the whole structure is like a broad-based V.

 

Pallial cavity. The gills are prominent globular masses, as in C. umbellata (Eberbach, 1915). They are relatively small (about 1/5-1/6 of the pallial area) and consist of six main laminae, of which the most interior is reduced. I ought to point out here in connection with the general problem of adaptation that, though the gills are reduced in size, the laminae are much more folded, so that the surface of each filament is increased. The median adductor is very small, as in C. umbellata (Ebersbach, l.c., fig. 3). On the other hand, owing to an excessive increase of connective tissue, the pallial cavity has become subdivided completely into two, a very unusual condition (cf. Robson, 1928, p. 261).

 

Alimentary canal (Fig. 4). The mandibles are present and, though somewhat soft, are normally developed. The palatal lamella of each is very small. The radula is absent. The anterior salivary glands are very small. There are no posterior salivary glands. The oesophagus is straight, and there is no crop. The lower end of the canal shows some peculiar features, which must be more fully discussed elsewhere. The stomach is equipped with a remarkably well-developed grinding apparatus. It contained a few fragments of Polychaeta. The caecum is much larger than the stomach, and may include part of the "third stomach" seen in Opisthoteuthis and C. umbellata. Its contents were so finely reduced that it was impossible to identify them. The intestine is bent on itself, as in Opisthoteuthis.

 

Reproductive organs (♂) (Fig. 5). There is no external trace of sexual differentiation, e.g. no abruptly enlarged suckers as in S. albatrossi and Opisthoteuthis (Sasaki, 1929, pp. 8, II). The internal organs are like those of C. umbellata (Ebersbach, loc. cit., Text-fig. 17) in general, but the proportions of the first accessory gland to the (conjoined) second and third is different.

 

 

REMARKS. This interesting form is like no described species. It seems to be most closely related to C. megaptera in external appearance. The internal organs are not un­like those of C. umbellata. The external appearance differentiates it at once from the other Antarctic species of Cirromorpha (S. mawsoni, Berry). It is a pity that Hoyle's Weddel Sea form (1912) was only fragmentary.

 

I hope shortly to publish a general discussion on this group. In the meantime, I must point out that the question of the adaptive significance of many of the peculiar features of these animals is rendered far more open than my recent account (1926) would lead one to suppose. In spite of the presence of some gelatinous tissue in C. glacialis, the arm- and fin-musculature is singularly powerful. The suckers are, if simpler in structure, more muscular than those of many Octopodinae, and are strangely assorted with the feeble mandibles and the absence of the radula. The gills, if small, have their small size compensated by the increased surface. The funnel and locking-apparatus are powerful;

 

the adductor pallii medianus, as in C. umbellata, is feeble. This sketch will sufficiently indicate that we have to deal with an actively swimming and darting form with need for an ample supply of oxygen. Its diet seems to be that of a carnivore, but it is not easy to reconcile the lack of radula and the weakness of the jaws with the presence of powerful suckers, unless it be that it is a carrion eater and the suckers are used not for grasping prey, but in coition.”

 

 

1 It is not at all like the original specimen of megaptera (Verrill, 1885, pl. xliii, fig. 1). It resembles a specimen taken in 16° 12' N, 24° 43' W and named megaptera by Joubin (loc. cit.). Very unfortunately Joubin did not describe this example in detail and I am quite unable to say if it is rightly named. Though it resembles this specimen in general proportion, the 'Discovery' example differs from it in the size and shape of its fins.

 

2 In Joubin's megaptera (loc. cit.) the sides of the fins seem to be parallel.

 

3 Since writing this description, which is based in the preserved specimen, I have seen the original colour-sketch made when the animal was alive. The circular band of pale colour turns out to be a circumoral ring of eight round white patches, each of which lies astride an arm. Between this ring and the mouth, the web was bright reddish purple; peripherally and beyond the ring it was of an intense bluish purple. This pattern and coloration are extremely vivid and arresting.

 

 

 

(Robson, 1930: 375-378)

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© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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