HeteroteuthinaeRichard E. Young, Clyde F. E. Roper, and Michael Vecchione
This tree diagram shows the relationships between several groups of organisms.
The root of the current tree connects the organisms featured in this tree to their containing group and the rest of the Tree of Life. The basal branching point in the tree represents the ancestor of the other groups in the tree. This ancestor diversified over time into several descendent subgroups, which are represented as internal nodes and terminal taxa to the right.
You can click on the root to travel down the Tree of Life all the way to the root of all Life, and you can click on the names of descendent subgroups to travel up the Tree of Life all the way to individual species.close box
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.
A sepiolid ...
- with a ventral mantle shield and silvery sides.
- Interbrachial web strongly developed connecting proximal halves of arms I-III.
- Arm suckers biserial except tips of arms IV where they 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 modified optically and morphologically to form a "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.
- Visceral photophores with single 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).
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|
Richard E. Young
University of Hawaii, Honolulu, HI, USA
Clyde F. E. Roper
Smithsonian Institution, Washington, D. C., USA
Page copyright © 2004 Richard E. Young, , and
- First online 30 August 2004
- Content changed 30 May 2007
Citing this page:
Young, Richard E., Roper, Clyde F. E., and Vecchione, Michael. 2007. Heteroteuthinae http://tolweb.org/Heteroteuthinae/20027/2007.05.30 in The Tree of Life Web Project, http://tolweb.org/. Version 30 May 2007 (under construction).