Overview

Brief Summary

Introduction

Members of the Ommastrephinae are the most oceanic members of the Ommastrephidae and are commonly attracted to surface night-lights in the open ocean. Some species are fished commercially and one species, Ommastrephes bartramii, was taken in the North Pacific in quantities over 350,000 tons per year during the 1980s (Bower and Ichii, 2005). This subfamily contains the largest species (Doscidicus gigas) reaching a size of 120 cm ML and the smallest species (Hyaloteuthis pelagica) reaching a size of about 9 cm ML (Nesis, 1982/87). A wide variety of luminous organs are present on the mantle, head, arms, viscera and eyes but vary with species.

Brief diagnosis:

Ommastrephids with ...

  • photophores.

Trusted

Article rating from 0 people

Average rating: 2.5 of 5

Comprehensive Description

Characteristics

  1. Arms
    1. Hectocotylus usually with distal ventral protective membrane expanded to form a flange (not expanded in Ommastrephes where it tapers toward tip).
    2. Hectocotylus possesses pores in some genera.

    Figure. Mostly oral views of hectocotylized left or right ventral arms of representatives of Ommastrephinae genera. A - Ommastrephes bartramii. B - Sthenoteuthis pteropus, right arm. C - Dosidicus gigas, right arm. D - Eucleoteuthis luminosa, left arm. E - Hyaloteuthis pelagica, distal part of left arm, simplified. F - Ornithoteuthis volatilis, distal 2/3 right arm; left - oral view; right - ventrolateral view. v - Ventral side of arm. Drawings from Roeleveld (1988). Arrows point to pores.

  2. Tentacles
    1. Suckers of dactylus of tentacular club in four series.
    2. Carpal locking-apparatus usually present with one to several smooth-ringed suckers and corresponding knobs (absent in Ornithoteuthis).

      Figure. Oral view of the tentacular club of O, bartramii, 303 m ML, off Baja California. Drawing from Young (1972).

  3. Head
    1. Funnel groove usually with anterior foveola and side pockets (both absent in Ornithoteuthis).

      Figure. Left - Ventral view of the funnel groove comparing modifications in two of the subfamilies. Drawing modified from Roper, et al. (1985). Right - Oral-oblique view of the funnel (with funnel valve protruding) and funnel groove of Sthenoteuthis oualaniensis showing foveola and side pockets. Photograph by R. Young.

  4. Photophores
    1. Photophores present in all species.
    2. Subcutaneous photophores present in all species except those of Ornithoteuthis.

    Figure. Ventral (top) and dorsal (bottom) views of the mantle of Sthenoteuthis oualaniensis that has been cleared and the photophores (and gladius, funnel locking-apparatus) stained with alcian blue stain. The numerous small, dark dots are subcutaneous photophores embedded in the mantle muscle. The lower, left arrow points to a dense patch of several hundred photophores. Photograph modified from Kishimoto and Kohno (1992).

    Table. Comparison of genera of Ommastrephinae
    Photophore patch on dorsal mantle
    Visceral photophores Enlarged, easily visible, subcutaneous photophores Largest manus sucker
    Hectocotyllus with lateral pores Arm tips
    Ornithoteuthis No One or two round organs, long streak None Toothed, no enlarged teeth
    Yes Normal
    Dosidicus No Two round organs, no streaks None Enlarged tooth in each quadrant
    Yes Attenuate at >35 cm ML, with 200-500 small suckers
    Ommastrephes No
    None None Enlarged tooth in each quadrant
    No Normal
    Sthenoteuthis Yes
    Two round organs, no streaks
    None Enlarged tooth in each quadrant
    Yes; No in early maturing form Normal
    Eucleoteuthis No
    One round organ, no streaks
    Circular pads and streaks Smooth except one tooth
    No Normal
    Hyaloteuthis No
    One round organ, no streaks
    Circular pads Smooth, sometimes one/few teeth
    No Normal

    Figure. Explanation of table characters: Types of largest manus suckers. Drawings from Roeleveld (1988).

Trusted

Article rating from 0 people

Average rating: 2.5 of 5

Disclaimer

EOL content is automatically assembled from many different content providers. As a result, from time to time you may find pages on EOL that are confusing.

To request an improvement, please leave a comment on the page. Thank you!