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Heteroteuthinae Appellof, 1898

Richard E. Young, Clyde F. E. Roper, and Michael Vecchione
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taxon links [up-->]Iridoteuthis [up-->]Sepiolina [up-->]Stoloteuthis [up-->]Nectoteuthis [up-->]Heteroteuthis [up-->]Amphorateuthis alveatus [down<--]Sepiolidae Interpreting the tree
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Containing group: Sepiolidae

Introduction

Heteroteuthins are small pelagic or benthopelagic sepiolids. They are easily recognized by their silvery sides and colorful ventral shield. The latter structure appears to be involved in directing and, perhaps, diffusing the light from their large visceral photophore.

Brief diagnosis

A sepiolid ...

Characteristics

  1. Arms
    1. Interbrachial web strongly developed connecting proximal halves of arms I-III.
    2. Arm suckers biserial except tips of arms IV where they become more numerous.
  2. Tentacles
    1. Tentacular clubs not expanded (except in Sepiolina).
    2. Keel present only at base of club as narrow elongate fold, paired with a reduced dorsal protective membrane to form "tentacle organ" (except in Sepiolina) of unknown function.
      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. Oral view of tentacular club of Heteroteuthis sp. showing the "tentacle organ" at the club base. Drawing by A. Hart.

  3. Mantle
    1. Ventral mantle modified optically and morphologically to form a "shield." Outside of the Heteroteuthinae a "shield" is found only in Choneteuthis tongaensis.
      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-oblique view of Iridoteuthis iris showing ventral shield. Photograph by Thomas Burch.

    2. Mantle fused to or free from head in nuchal region.
  4. Gladius
    1. Gladius absent.
  5. Viscera
    1. Bursa copulatrix absent.
  6. Photophores
    1. Visceral photophores with single large circular lens on ventral surface of ink sac.

Comments

The ventral shield on the mantle is thought to diffuse the light from the visceral photophore over the region of the shield and thereby aid in counterillumination (eliminate the shadow of the animal created by dim downwelling light).

The following table compares the six genera.

  Tentacle organ Arm modifications in males Enlarged suckers, males Arm modifications in females Mantle-head fusion Funnel locking-apparatus Length of ventral shield
Heteroteuthis Yes Strong asymmetry, right arms I & II, modified and with glands Arms III Arm I & II tips bare None Deep curved goove 50% VML
Iridoteuthis Yes No strong asymmetry, all arms I-III modified, no glands

Arms I & III

 Arm III & IV tips with trabeculae Broad Straight groove and deep pit >80% VML
Nectoteuthis Yes No asymmetry, distal arm suckers on long stalks None ? None Deep, broad pit and shallow pit >80% VML
NewGenus Yes No asymmetry, arms II-IV modified Arms III Arms III, distal half bare. Broad Straight groove and deep pit >80%
Sepiolina No No asymmetry, arms I with glands Arms II & III None Narrow Elongate pit and short groove >80% VML
Stoloteuthis Yes No asymmetry, arms I with larger basal suckers and glands Arms II None Narrow Straight groove >80% VML
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 Iridoteuthis iris
Location off Hawaii
View Side
Size about 18 mm ML
Copyright © 1996 Thomas Burch
Scientific Name Heteroteuthis hawaiiensis
Location Hawaiian waters
View Side
Copyright © 2004 Richard E. Young
About This Page

Richard E. Young
University of Hawaii, Honolulu, HI, USA

Clyde F. E. Roper
Smithsonian Institution, Washington, D. C., USA


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

Citing this page:

Young, Richard E., Roper, Clyde F. E., and Vecchione, Michael. 2007. Heteroteuthinae Appellof, 1898. Version 30 May 2007 (under construction). http://tolweb.org/Heteroteuthinae/20027/2007.05.30 in The Tree of Life Web Project, http://tolweb.org/

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