Overview

Brief Summary

Introduction

C. magna is a large (up to 1200 mm TL) but fragile deep-sea cirrate that is known from 4 specimens captured from the Atlantic, Pacific and Indian Oceans.

Diagnosis

A Cirrothauma ...

  • with normal eyes bearing lenses.

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Comprehensive Description

Nomenclature

C. magna was traditionally placed in Cirroteuthis although Robson (1932) and Nesis (1987) questioned this placement. O'Shea (1999) noted the similarity of the shell to that of Cirrothauma and moved the species to that genus.

Hoyle (1886) described a second but mutilated specimen along with his redescription of the holotype. Robson (1932) suggested that this second specimen belonged to a separate species which he named Cirroteuthis hoylei. The status of this latter species is uncertain.

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Characteristics

  1. Eyes
    1. Functional eyes (eyes with lenses).

    Figure. Eye of C. magna, male, 220 mm ML. At the far right of the drawing is the optic stalk that enters the optic lobe of the brain. From this the optic nerves pass through the white body and into the eyeball. Drawing from Guerra, et al., 1998.

  2. Suckers
    1. Arms with 3 types of suckers (top figure; bottom figure shows the two more distal types).
    2. Suckers nearest mouth: small, cyclindrical, closely spaced, with stout stalk.
    3. Following suckers: larger and on long stalks; thin, broad, infundibulum with small openings (acetabulum, apparently, nearly absent); infundibulum can inflate or deflate to form a spherical (see middle sucker in bottom drawing), flattened or "half-closed eyelid."
    4. Suckers of distal third of arm: large, fleshy with bowl-like, amphora-like or barrel-like shape; sessile with rigid, muscular base (however see top figure where these suckers have long stalks).

    Figure. Top - Three sections of the arm, submature female of C. magna, 140 mm ML. Bottom - Two sections of the arm, mature male, 220 mm ML. Drawings from Guerra, et al., 1998.

  3. Web
    1. Distal web attachments to each arm asymmetrical.
    2. Web nodules absent.

Comments

The above description is taken from Guerra et al., 1998. Additional features of the description can be found here.

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C. magna is, as other cirrate octopods, a cephalopod, typically adapted to the deep-sea environment in the abyssal ecosystem. These gelatinous animals are neutrally buoyant. They can be considered as abyssopelagic animals, although they can also rest on the bottom, where they probably feed. Its voluminous and operative eyes indicate that these animals are able to detect light produced by themselves, other animals of the same species, or by potential predators and prey. This species, and other related ones, have been observed to swim at 2.2 km/h and 0.46 km/h. It occurs near hydrothermal vents, but was rarely observed at the Mid-Atlantic Ridge.
  • GUERRA A.R., VILLANUEVA R., NESIS K. & J. BEDOYA (1998) Bull. Mar. Sci. 63(1): 51-81.

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Distribution

Type locality: 46°46'S, 45°31'E, south Indian Ocean between Prince Edward Island and the Crozets, 2557 m.

The specimens described by Guerra, et al. (1998) were taken at 15°29'N, 46°34'W in the central North Atlantic (male) and 23°00'N, 17°34'W in the North Alantic off West Africa (female).

O'Shea (1999) suspects that a specimen taken off New Zealand at 39°58'S, 178°02'E, 1450-1468 m, represents a new species.

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South Indian (2557 m) and Pacific (1500 m) to subtropical North Atlantic (1350 m). One specimen (1300 mm length) was caught at the Mid-Atlantic Ridge, near Logatchev, 3351 m. Another specimen was captured near a vent site in the southern East Pacific Rise: 17°S, 2574 m (M. Lilley & K. Van Damm, chief Scientists; J. Voight, det.).
  • GUERRA A.R., VILLANUEVA R., NESIS K. & J. BEDOYA (1998) Bull. Mar. Sci. 63(1): 51-81.

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Physical Description

Morphology

Deep-sea animals of very great size (up to 1300 mm TL). Butterfly-like shell. Shell Width Index: 26-31. Very voluminous eyes (Eye-ball Diameter Index: 39-43), with large lenses (Lens Diameter Index: 12-18). Arm length up to 940 mm. Primary web inserting at different levels on the oral and aboral ends of the dorso-lateral and ventro-lateral arms on both sides, and at the same levels on both ends of the dorsal and ventral arms. Very long non-retractile cirri (Cirrus Length Index: 96-71); the first cirri commences between the fourth and fifth suckers. Three types of suckers on all arms: cylindro-conical form and those with the acetabulum highly deformable on the first 2/3 and barrel-shaped on the rest of the arm; no enlarged suckers in male or female.
  • GUERRA A.R., VILLANUEVA R., NESIS K. & J. BEDOYA (1998) Bull. Mar. Sci. 63(1): 51-81.

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Size

Up to 1300 mm total length. The largest known cirrate octopod.
  • GUERRA A.R., VILLANUEVA R., NESIS K. & J. BEDOYA (1998) Bull. Mar. Sci. 63(1): 51-81.

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Ecology

Habitat

Depth range based on 1 specimen in 1 taxon.
Water temperature and chemistry ranges based on 1 sample.

Environmental ranges
  Depth range (m): 2340 - 2340
  Temperature range (°C): 2.909 - 2.909
  Nitrate (umol/L): 16.616 - 16.616
  Salinity (PPS): 34.977 - 34.977
  Oxygen (ml/l): 6.309 - 6.309
  Phosphate (umol/l): 1.116 - 1.116
  Silicate (umol/l): 13.890 - 13.890
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Depth range based on 2 specimens in 1 taxon.
Water temperature and chemistry ranges based on 2 samples.

Environmental ranges
  Depth range (m): 2600 - 3500
  Temperature range (°C): 1.823 - 2.523
  Nitrate (umol/L): 22.153 - 36.252
  Salinity (PPS): 34.674 - 34.913
  Oxygen (ml/l): 3.489 - 5.657
  Phosphate (umol/l): 1.412 - 2.500
  Silicate (umol/l): 42.727 - 127.119

Graphical representation

Depth range (m): 2600 - 3500

Temperature range (°C): 1.823 - 2.523

Nitrate (umol/L): 22.153 - 36.252

Salinity (PPS): 34.674 - 34.913

Oxygen (ml/l): 3.489 - 5.657

Phosphate (umol/l): 1.412 - 2.500

Silicate (umol/l): 42.727 - 127.119
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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