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Megalocranchia Pfeffer, 1884

Richard E. Young and Katharina M. Mangold (1922-2003)
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Megalocranchia contains four recognized species. Voss, et al. (1992), however, suggest that six species exist.

Containing group: Taoniinae

Introduction

Some species of Megalocranchia are very large and can reach 1800 mm ML, (Tsuchiya and Okutani, 1993). The vertical distribution is best known in M. fisheri. The paralarval stage, which reaches 40-50 mm ML, is spent in near-surface waters. Larger individuals occupy mesopelagic depths during the day and migrate into near-surface waters at night (Young, 1978).

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Figure. Side view of earyl juvenile M. fisheri. Photograph by R. Young.

Brief diagnosis:

A taoniin ...

Characteristics

  1. Tentacles
    1. Tentacular clubs with suckers only.
    2. Tentacular stalk with two series of suckers and pads in mid-third, then four series to carpal group.

  2. Head
    1. Beaks: Descriptions can be found here: M. fisheri Lower beak, upper beak; M. oceanica lower beak, upper beak.

  3. Funnel
    1. Funnel valve present.
    2. Funnel organ: Dorsal pad with two triangular flaps, no papillae.

  4. Mantle
    1. Tubercules absent at funnel-mantle fusion.
    2. Paralarvae (to ca. 50 mm ML) with thick gelatinous dermis on mantle.*

  5. Fin
    1. Anterior 10-15% of fin inserts on mantle (in subadults).**

  6. Photophores
    1. Photophores present on digestive gland.*
    2. Photophores present on tips of arms I-III or only II or only III of adult females.
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      Click on an image to view larger version & data in a new window

      Figure. Visceral photophores from a subadult, M. fisheri, off Hawaii. The visceral photophores contain four reflecting cups (green). The intestine, partially covered with red pigment, is seen here passing between photophores of either side. The barely-discernable digestive gland is the fuzzy central dark region. Photograph by R. E. Young.

*Within family, unique to this genus.
**Within family, unique degree of mantle attachment. Most genera lack a mantle attachment but two have more than 30% of fin attached to the mantle(Egea, Teuthowenia) rather than to the gladius.

Comments

Characteristics are from Voss (1980).

Life History

Paralarvae of M. fisheri from Hawaiian waters have been identified. The large posterodorsal mantle chromatophore seen in both stages is distinctive among cranchiid paralarvae from these waters. What appears to be an unusually long club may actually be a combination of the club with a large number of carpal suckers on the distal stalk. Large paralarvae and early juveniles, at least, have a thick gelatinous layer in the skin which can be seen in the photographs below and above. A layer of orange chromatophores in skin both external to and internal to the gelatinous layer. The gelatinous makes the squid very difficult to pick up from trawl catches as the squid quickly slips through ones fingers.

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Click on an image to view larger version & data in a new window
             

Figure. Paralarvae of M. fisheri, Hawaiian waters. Thumbnail (far left) - Illustration shows relative sizes of the two paralarvae. Left - Ventral and dorsal views of a 4.9 mm ML paralarva and ventral and dorsal views of a 14.5 mm ML paralarva. The scale bars are 1 mm. Drawings by R. Young. Right - In situ photogaphs, anteroventrolateral view and dorsal views, about 20-30 mm ML. Image is a composite of under water photographs taken while scuba diving, © 2014 Jeffrey Milsen

Distribution

This genus occurs circumglobally in tropical and subtropical waters (Voss, 1992).

References

Tsuchiya, K. and T. Okutani. 1993. Rare and interesting squids in Japan -X. Recent occurrences of big squids from Okinawa. Venus 52: 299-311.

Voss, N. A. (1980). A generic revision of the Cranchiidae (Cephalopoda; Oegopsida). Bull. Mar. Sci., 30: 365-412.

Voss N. A., S. J. Stephen and Zh. Dong 1992. Family Cranchiidae Prosch, 1849. Smithson. Contr. Zool., 513: 187-210.

Young, R. E. 1978. Vertical distribution and photosensitive vesicles of pelagic cephalopods from Hawaiian waters. Fish. Bull. 76: 583-615.

Title Illustrations
Click on an image to view larger version & data in a new window
Click on an image to view larger version & data in a new window
Scientific Name Megalocranchia fisheri
Location off Hawaii
Specimen Condition Dead Specimen
Sex Female
Size large, 2.7 m total length
Image Use creative commons This media file is licensed under the Creative Commons Attribution-NonCommercial License - Version 3.0.
Copyright ©
Scientific Name Megalocranchia
Reference Voss, N. A. (1980). A generic revision of the Cranchiidae (Cephalopoda; Oegopsida). Bull. Mar. Sci., 30: 365-412. p. 399, Fig. 12a
Copyright © 1980 Bulletin of Marine Science
About This Page
Drawings from Voss (1980) printed with the Permission of the Bulletin of Marine Science.


University of Hawaii, Honolulu, HI, USA

Katharina M. Mangold (1922-2003)
Laboratoire Arago, Banyuls-Sur-Mer, France

Page: Tree of Life Megalocranchia Pfeffer, 1884. Authored by Richard E. Young and Katharina M. Mangold (1922-2003). The TEXT of this page is licensed under the Creative Commons Attribution-NonCommercial License - Version 3.0. Note that images and other media featured on this page are each governed by their own license, and they may or may not be available for reuse. Click on an image or a media link to access the media data window, which provides the relevant licensing information. For the general terms and conditions of ToL material reuse and redistribution, please see the Tree of Life Copyright Policies.

Citing this page:

Young, Richard E. and Katharina M. Mangold (1922-2003). 2015. Megalocranchia Pfeffer, 1884. Version 26 February 2015 (under construction). http://tolweb.org/Megalocranchia/19562/2015.02.26 in The Tree of Life Web Project, http://tolweb.org/

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