HeteroteuthinaeRichard E. Young, Clyde F. E. Roper, and Michael Vecchione
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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 diffusing the light from their large visceral photophore.
A sepiolid with ...
- ventral mantle shield and silvery sides.
- with arms I-III joined by deep web.
- Interbrachial web strongly developed connecting proximal halves of arms I-III.
- Arm suckers biserial except tips of arms IV where they may become more numerous.
- Tentacular clubs not expanded (except in Sepiolina).
- 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.
- Ventral mantle margin projects anteriorly.
- Ventral mantle modified optically and morphologically to form "ventral shield." Outside of the Heteroteuthinae a "shield" is found only in Choneteuthis tongaensis.
- Mantle fused to or free from head in nuchal region.
- Gladius absent.
- Bursa copulatrix absent.
- Single visceral photophore (with large circular "lens") on ventral surface of ink sac.
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). No expermental evidence exists, however, to support this assumption.
The following table compares the six genera.
|Tentacle organ||Arm modifications in males||Enlarged suckers, males||Mantle-head fusion||Funnel locking-apparatus||Length of ventral shield||Posterior fin lobes|
|Heteroteuthis||Proximal to sucker-bearing club ||Strong asymmetry of right arms I & II. Right arm II with glands||Arms III||None||Deep curved goove||50% VML||Rounded|
|Iridoteuthis||Along much of sucker-bearing club ||No strong asymmetry, no glands||Complex or none ||Broad||Straight or curved groove and deep, angular pit||>80% VML||Angled|
|Nectoteuthis||Unknown||No asymmetry, arm suckers tubular, glands unknown||Unknown||None||Groove with two pits: Deep, broad anterior; shallow posterior||>80% VML||Rounded|
|Amphorateuthis||Along much of sucker-bearing club||No asymmetry, arm suckers tubular in males. No glands ||Arms III||Broad||Straight groove and deep anterior pit||>80%||Angled|
|Sepiolina||Absent||No asymmetry. Arms I with glands||Arms II & III||Narrow||Elongate anterior pit and short groove||>80% VML||Rounded |
|Stoloteuthis||Proximal to sucker-bearing club or barely overlapping ||No asymmetry. Arms I with glands||Arms II||Narrow, broad or none ||Straight groove||>80% VML||Rounded or angled |
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- First online 30 August 2004
- Content changed 03 November 2013
Citing this page:
Young, Richard E., Clyde F. E. Roper, and Michael Vecchione. 2013. Heteroteuthinae http://tolweb.org/Heteroteuthinae/20027/2013.11.03 in The Tree of Life Web Project, http://tolweb.org/. Version 03 November 2013 (under construction).