Overview

Brief Summary

Introduction

The original description of G. megaptera was based mostly on two specimens but another two were captured at a nearby station and a small one from another station. Two and probably three of these specimens belong to another species (see below). A more complete description of this species is needed.

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Comprehensive Description

Description

Cirrhoteuthis megaptera Verrill, sp. nov.

 

 

PLATE XLIII, FIGURES 1, 2.

 

 

Body small, very short, depressed, broadly rounded posteriorly, broader than long. Fins very long and narrow, their length considerably exceeding the breadth of the body, in alcoholic specimens; toward the base they are much thickened and supported by an inter­nal cartilage, which does not appear to be continuous with the thin cartilage that extends across the body, just behind the fins. The fins are inserted just behind the eyes, and their breadth is somewhat greater in the middle than at the base; they narrow but little toward the tip, which is obtusely rounded. Head large and broad, exceed­ing the body in size and thickness in the preserved specimens, the greatest thickness being at the base of the arms. Eyes small, lateral, very far apart, the distance between them being, on the dorsal side, more than twice their diameter. Siphon short, conical, with a broad base. Gill-opening small, simple, only a little broader than the base of the siphon. Arms long, thick and strong, the dorsal ones a little longer than the others, which decrease successively to the ventral pair, which are, however, but little shorter than the third pair. The arms are thick and well rounded, especially on the basal portion, with the inner surface elevated along the median line, on which the suckers are arranged in a simple row; the marginal angles are but slightly indicated, and bear a row of small, slender, tapering cirri, alternating with the suckers, which are very small, urceolate, strongly elevated above the surface of the arms, and of a light yellow color, in strong contrast with the chocolate-brown of the arms. The dis­tance between the suckers along the middle portion of the arm usually considerably exceeds, and is often double their diameter, but varies with the state of contraction of the arms; at the base of the arms they diminish in size and become more crowded; towards the ends they diminish very gradually, finally becoming very small and closely arranged. The web between the arms is very thick, swollen at the base, and on the dorsal side extends more than half the length of the arms; it is successively a little shorter between the lateral arms, and still shorter between the ventral ones. The color of the body and fins in the alcoholic specimens is bluish white, covered with rather large and irregularly arranged specks and spots of pur­plish brown. The same color extends more or less on the head, becoming paler and more gelatinous or translucent on the web at the base of the arms, through which the dark brown color of the arms can be distinctly seen. The arms, the outer portion of the web, and its entire inner surface are dark chocolate-brown. The suckers are yellowish white, with brown rims.

 

Total length, in alcohol, 107mm; length of body to gill-opening, 25 mm; breadth of body at base of fins, 20 mm; total breadth across outstretched fins, 68 mm; length of fins from base to tip, 24 mm; breadth across middle, 9 mm; at base, 8 mm; breadth of head at the eyes, 27 mm; across base of arms, 30 mm; diameter of eyes, 9 mm; breadth of gill-opening, 8 mm; length of siphon, 8 mm; length of dorsal arms, 95 mm; breadth in middle, 6.7 mm; diameter of largest suckers, l mm; length of the longest cirri, 2 mm; length of second pair, 85 mm; third pair, 80 mm; ventral pair, 78 mm; extent of web between dorsal arms, 45 mm; between first and second pairs, 42 mm; between the third and fourth, 32 mm. The other specimen of this species has the body and head nearly the same size, but these parts may be more contracted by the alcohol; the fins and arms are somewhat longer and larger. The length of one of the fins is 33 mm; its greatest breadth, 11 mm; across eyes, 27 mm; diameter of eye, 8 mm; diameter of largest sucker, less than 1 mm.

 

The sex of the two specimens described above is uncertain. There is no positive appearance of hectocotylization in any of the arms, but in the specimen first described the left arm of the second pair has a blunt, pale tip, before which the suckers cease abruptly, yet this is most likely due to the early stages of the reproduction of a new tip.

 

Sketches of this species were made by Mr. A. Baldwin, on the steamer, when the specimens first came up and had some life. From his sketches the figures on plate xliii have been made.

 

In the living state, according to these and other sketches, the fins are much larger and broader, with the end more rounded; and the anterior edge is thinner and more convex, than after preservation in alcohol, though the length is not much greater in proportion. The web appears broader, and the arms longer. In one specimen, from station 2224, the body is more elongated behind the fins than in the others, while the long and very broad fins are placed some distance back from the eyes, or about midway between the eyes and the end of the body, and the web does not extend half the length of the arms. It was at first thought that this individual might represent another species, but these creatures are evidently capable of changing their forms and proportions to a great extent, according to the state of contraction of their various parts.

 

Both the larger specimens of this species have a curious appendage on most, if not all, of the arms. This is a fleshy, tentacle-like pro­cess, with a somewhat thickened base, and a tapering, acute tip. It is situated at about the distal third of the arm, on the posterior side, near the edge of the web, and diverges widely from the arm. In one specimen this is present on all the arms of the left side and on two of those on the right side. On the other arms they probably have been destroyed, the arms being injured. The length of this organ is about equal to the breadth of the arms. When perfect these organs, which are muscular, were probably united to the web, and served to support or strengthen it. I am not aware that an organ of this kind has before been observed among the Cephalopods. But it may, perhaps, correspond to one of the transverse supports of the mar­ginal membranes of Sthenoteuthis and Ommastrephes.

 

Two specimens (No. 39,963) were taken at station 2,225, N. lat. 36° 05' 30", W. long. 69° 51' 45", in 2,512 fathoms, on yellow ooze, bottom temperature 37° F.; and two at station 2,224, N. lat. 36° 16' 30", W. long. 68° 21', in 2,574 fathoms, globigerina ooze.

 

A small specimen, from station 2,220, appears to be a younger stage of this species, with which it agrees, in the small, short body; the narrow, elongated fins, and the comparatively small eyes, as well as in the chocolate-brown color of the inner surfaces of the arms and web; but the external surfaces of the body, web and arms are also strongly colored with deep brown. The arms in this specimen are nearly equal in length, the ventral ones, being a little shorter than the others. The web appears to extend farther toward the tips of the arms than in the larger examples, but this may be due to better preservation. The suckers are small, prominent, and closely ar­ranged.

 

The total length of this specimen is 43 mm; posterior end of body to gill-opening, 13 mm; breadth of body at fins, 13 mm; length of fins, 9 mm; breadth, 4.5 mm; breadth of head across eyes, 17 mm; diameter of eye, 7 mm; from center of eye to tip of dorsal arms, 34 mm; to edge of web between dorsal arms, 23 mm; to tip of lateral arms, 31 mm; to edge of lateral web, 21 mm.

 

Station 2,220, N. lat. 39° 43' 30", W. long. 69° 23', in 1,054 fathoms, (No. 39,916).

 

This species appears to be closely related to C. plena in most respects, but has a very much smaller and shorter body, larger and relatively much longer fins, and the eyes are relatively smaller. The suckers are also smaller, more prominent, and less closely arranged, while the cirri are somewhat longer and more slender. The color of the body and arms is also much darker, and the texture less gelatinous.”

 

 

(Verrill, 1885: 405-408)

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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Characteristics

  1. Arms and web
    1. Arms I slightly the longest.
    2. Suckers small (1.0 mm diam.), urn-like, strongly elevated above arm surface.
    3. Distance between suckers in midarm often 2 times sucker diameter.
    4. Suckers small and closely packed proximally and distally.
    5. Maximum cirrus length, 2 mm.
    6. Web nodules present on ventral side of each arm.

    Figure. Oral view of the arms and web of G. megaptera. Drawing from Verrill, 1885.

  2. Eyes
    1. "Small", separated by more than 2 times eye diameter.

  3. Shell
    1. Not described.

  4. Color
    1. Oral surfaces of arms and web chocolate-brown.
    2. Suckers light yellow with brown rims.
    3. Mantle, fins and head bluish white covered with rather large and irregularly arranged, purplish-brown specks and spots.
    4. Web paler and more translucent aborally.

  5. Measurements
    1. Measurements of G. megaptera can be found here.

Comments

The above description is from Verrill, 1885.

There are some differences between the type description which was based on an animal preserved in alcohol and the type illustration which was based on sketches of the fresh animal.

Martin Collins writes: "The type material of G. megaptera appears to be lost, the two specimens in the Smithsonian were in fact C. murrayi. Verrill had four specimens, but the whereabouts of the other two (the real megaptera types) is not known. I have examined 20-30 specimens from the NW Atlantic, and there are at least two species in the material, one of which may be megaptera. Again new material from the type location is needed." Collins (in press) examined a recent specimen from near the type locality of G. megaptera. This specimen had 90 suckers on each arm (ML 120 mm, max. sucker diam. 3.9 mm, max. cirrus length 4 mm).

Among other Atlantic species, Grimpoteuthis megaptera differs from:

  • G. boylei in geographic distribution (Western vs Eastern North Atlantic) and, perhaps, the smaller sucker size (Collins, 2002).
  • G. challengeri in the shorter cirri (2x vs 2.5x in males, 3.5x in females) (Collins, 2002), but cannot be reliably separated from G. megaptera.
  • G. discoveryi in geographic distribution (Western vs Eastern North Atlantic), having smaller sucker size (3.7 vs mean 6.4 in males, 4.4 in females) and shorter cirri (2x vs 1.2x in males, 1.6x in females) (Collins, 2002). The imprecise measurements of suckers and cirri in G. megaptera makes the latter two characters questionable.
  • G. plena in having a much smaller and shorter body, larger fins and relatively smaller eyes, smaller, more prominent and less closely-packed suckers, and longer, more slender cirri (Verrill, 1885).
  • G. wuelkeri in having a greater depth habitat (>4000 m vs <2100 m) and, perhaps a smaller sucker diameter (1 vs 1.5-2.2 for octopods with arms I about 100 mm) (Collins, 2002).

If the specimen examined by M. Collins from near the type locality (see above) is G. megaptera then the very large number of suckers will separate this species from all other Atlantic species.

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Distribution

Western Atlantic: Southeast of Long Island
  • North-West Atlantic Ocean species (NWARMS)
Creative Commons Attribution 3.0 (CC BY 3.0)

© WoRMS for SMEBD

Source: World Register of Marine Species

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The type locality is: Southeast of Martha's Vineyard, off N. E. coast of United States, 36°05.5'N, 69°51.8'W, 4600 m depth and at 36°16.5'N, 68°21'W.

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Ecology

Habitat

bathyal to abyssal
  • UNESCO-IOC Register of Marine Organisms
Creative Commons Attribution 3.0 (CC BY 3.0)

© WoRMS for SMEBD

Source: World Register of Marine Species

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