Under Construction

Onykia (Onykia) robusta (Verrill, 1876)

Michael Vecchione, Richard E. Young, and Kotaro Tsuchiya
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
Original name --Ommastrephes robustus Verrill, 1876
Containing group: Onykia

Introduction

O. robusta is the type species of the former genus Moroteuthis and largest species of the genus. It reaches a length of at least 1615 mm ML (Kubodera, et al, 1998). This species is found only in the high North Pacific.

Diagnosis

An Onykia ...

Characteristics

  1. Tentacles
    1. Club with 15-18 pairs of hooks.

      Scanning electron micrographs of the hooks can be seen here.

    2. Suckers of marginal series absent at greater than 61 mm ML.

  2. Head
    1. Beaks: Descriptions can be found here: Lower beak; upper beak.

  3. Mantle
    1. Dermis of mantle skin with longitudinal ridges.

  4. Fins
    1. Sagittate shape beyond 94 mm ML.
    2. Length 50-65% of ML.
    3. Width 60-70% of ML.

  5. Gladius
    1. Rostrum 25-40% of GL; opaque, circular in cross-section.
      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

      Figure. Ventral view of gladius of O. robusta with cross-sections. Drawing from Sasaki 1929.

comments

Additional features of the description are found here.

Nomenclature

O. japonica (Taki, 1964) and O. pacifica (Okutani, 1983) are junior synonyms (Tsuchiya and Okutani, 1991).

Life History

At less than 43 mm ML, the mantle has an irridescent epidermis overlying numerous indistinct ridges; at 61 mm ML, the mantle surface has fleshy ridges and a weak iridescence; at 94mm ML no iridescence remains. The shape of the fins changes greatly with growth from oval in combined outline at less than 20 mm ML to saggitate in adults. The rostral cap is 20% of the ML at 43 mm ML and 30% at 100 mm ML. The inverted Y-shaped ridge is detectable in specimens larger than 60 mm ML. By 61 mm ML all marginal suckers on the club are absent. This life history data is from Tsuchiya and Okutani, 1991.

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

Figure. Development of the tentacular club of O. robusta. A - 19.4 mm ML. B - 42.8 mm ML. C - 60.5 mm ML. D - 135 mm ML. Scale bar is 10 mm.

Changes in body proportions with growth have been illustrated by Tsuchiya and Okutani (1991).

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

Figure. Ventral views of O. robusta at various sizes. A - 19.4 mm ML. B - 42.8 mm ML. C - 60.7 mm ML. D - 135 mm ML. E - 181 mm ML. F - 1615 mm ML. Scale bar = 2 cm. Drawings from Tsuchiya and Okutani (1991, p. 139).

Changes in body form are reflected in changes in the shape of the gladius.

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

Figure. Ventral views of the gladii of O. robusta. A - 42.8 mm ML. B - 181 mm ML. Drawings from Tsuchiya and Okutani (1991, p. 142).

Distribution

This species is found in the temperate to boreal North Pacific (Kubodera, et al., 1998)

Other Names for Onykia (Onykia) robusta (Verrill, 1876)

References

T. Kubodera, U. Piatkowski, T. Okutani and M.R. Clarke. 1998. Taxonomy and Zoogeography of the Family Onychoteuthidae (Cephalopoda: Oegopsida). Smithsonian Contributions to Zoology, No. 586: 277-291.

Tsuchiya, K., and T. Okutani. 1991. Growth Stages of Moroteuthis robusta (Verrill, 1881) with the Re-evaluation of the Genus. Bulletin of Marine Science, 49(1-2):137-147.

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 Onykia (Onykia) robusta
Location Eastern North Pacific off Monterey, California at 36.97N, 121.85W
Comments In situ photograph of O. robusta taken at a depth of 290 m.
Acknowledgements Image courtesy of the Monterey Bay Aquarium Research Institute (MBARI). You must obtain permission from MBARI to use this photo; please contact pressroom@mbari.org for further information.
Specimen Condition Live Specimen
Identified By R. E. Young
View Side
Size Unknown
Copyright © 2013 MBARI
Scientific Name Onykia robusta
Reference T. Kubodera, U. Piatkowski, T. Okutani and M.R. Clarke. 1998. Taxonomy and Zoogeography of the Family Onychoteuthidae (Cephalopoda: Oegopsida). Smithsonian Contributions to Zoology, No. 586: 277-291.
View Ventral
About This Page
Figures from Tsuchiya and Okutani printed with the Permission of the Bulletin of Marine Science.


National Museum of Natural History, Washington, D. C. , USA


University of Hawaii, Honolulu, HI, USA


Tokyo University of Fisheries, Tokyo, Japan

Page: Tree of Life Onykia (Onykia) robusta (Verrill, 1876). Authored by Michael Vecchione, Richard E. Young, and Kotaro Tsuchiya. 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:

Vecchione, Michael, Richard E. Young, and Kotaro Tsuchiya. 2013. Onykia (Onykia) robusta (Verrill, 1876). Version 08 January 2013 (under construction). http://tolweb.org/Onykia_%28Onykia%29_robusta/19976/2013.01.08 in The Tree of Life Web Project, http://tolweb.org/

edit this page
close box

This page is a Tree of Life Leaf Page.

Each ToL leaf page provides a synopsis of the characteristics of a group of organisms representing a leaf at the tip of the Tree of Life. The major distinction between a leaf and a branch of the Tree of Life is that a leaf cannot generally be further subdivided into subgroups representing distinct genetic lineages.

For a more detailed explanation of the different ToL page types, have a look at the Structure of the Tree of Life page.

close box

Onykia (Onykia) robusta

Page Content

articles & notes

collections

people

Explore Other Groups

random page

  go to the Tree of Life home page
top