Note

Onykia robsoni: Club Hooks

Richard E. Young, Michael Vecchione, and Kotaro Tsuchiya

Two club hooks were examined with the scanning electron microscope (SEM). Their relative sizes are seen in the photograph below. Hook number 7 from the proximal end of the ventral hook series (ie, hook V7) (right in photograph) was the largest of all the club hooks. Its mate from the dorsal hook series (hook D7) is seen on the left. Note the near bilateral symmetry of hook V7.

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

Figure. Frontal views of hooks D7 (left) and V7 (right) of O. robsoni (?), 145 mm ML, continental slope south of New England, USA . Photographs by R. Young.

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

Figure. Top-frontal view of the two hooks (V7 at left, D7 at right). The proximal lateral lobe in V7 is slightly smaller than the distal lateral lobe. The proximal lip of this hook lacks a hair-lip but the edge curls slightly at this position. The lateral claw grooves extend nearly to the tip of the claw. The claw tip of hook D7 is broken off.

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

Figure. Lateral views of the two hooks (hook V7 at left, D7 at right).

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

Figure. Attachment-site views of the two hooks (hook V7 at left, D7 at right).

Comments

Of the three species of Onykia examined with the SEM, the general appearance of O. robsoni is similar to O. robusta. The specimen of O. robsoni examined here is the same as that in the title photograph on the O. carriboea web page. Hooks from a larger (304 mm ML) specimen from the Gulf of Mexico looked similar but had a bit more asymmetry between the lateral lobes of the ventral-series hook.

About This Page


University of Hawaii, Honolulu, HI, USA


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


Tokyo University of Fisheries, Tokyo, Japan

Page: Tree of Life Onykia robsoni: Club Hooks Authored by Richard E. Young, Michael Vecchione, 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.

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Onykia (Onykia) robsoni

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