Sepioidea
Michael Vecchione and Richard E. YoungThis tree diagram shows the relationships between several groups of organisms.
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close boxIntroduction
We place three families in the sepioid clade: Sepiidae, Sepiadariidae and Sepiolidae. The latter two families are related and placed in the suborder Sepiolida. Two additional families (Idiosepiidae, Spirulidae) have often been included in the Order Sepioidea. However considerable uncertainty exists concerning the relationships of the Idiospiidae in general and the closeness of the relationship of the Spirulidae to the sepioid families. Members of the sepioidea are mostly neritic and upper slope benthic species although one group (Heteroteuthinae) is pelagic.
Diagnosis
A decapodiform ...
- with corneal membranes covering eye lenses.
- without branchial canals in gills.
- with circularis muscles in suckers.
Characteristics
- Arms
- Suckers with circularis muscles.
- Suckers with circularis muscles.
- Tentacles
- Tentacular club without proximal (= carpal) locking-apparatus.
- Suckers with circularis muscles. Click on an image to view larger version & data in a new window
Figure. Sections through the club suckers. Left - Sepia officinalis, arrow points to circularis muscle which encircles the sucker. Middle - Ommastrephes bartramii. Note absence of a circularis muscle. Right - Sepia officinalis, section at right angles to left figure, circularis muscle in blue; the asymmetry in the muscle is revealed by the angle of section. Histological sections made by Barbara Littman; photographed by R. Young. Drawing modified from Naef (1921-23).
- Buccal crown
- Buccal supports with or without suckers.
- Buccal supports with or without suckers.
- Head
- Head with tentacle pocket.
- Eyes with corneal membranes covering lenses.
- Eyes with secondary (= ventral) eyelid (except in some Sepiolidae).
- Funnel
- Funnel with lateral adductor muscles (except in some Sepiolidae).
- Mantle
- Mantle locking-apparatus does not reach anterior mantle margin (see short arrow in above photograph which marks the anterior end of the mantle locking-apparatus) except in some Sepiolidae.
- Interstellate connective absent (ie, no direct nerve connective passes directly from one stellate ganglion to the other).
- Mantle locking-apparatus does not reach anterior mantle margin (see short arrow in above photograph which marks the anterior end of the mantle locking-apparatus) except in some Sepiolidae.
- Fins
- Fins completely separate from one another; usually with posterior lobes.
- Fins completely separate from one another; usually with posterior lobes.
- Shell
- Shell a flattened phragmocone (=cuttlebone), a gladius or absent.
- Shell a flattened phragmocone (=cuttlebone), a gladius or absent.
- Viscera
- Gills without branchial canal.
- Right oviduct absent.
- Females with accessory nidamental glands.
- Eggs
- Eggs, where known, attached to substrate singly or in unorganized groups.
Synapomorphies
Many of the above characteristics of the Sepioidea are shared with the Myopsida. The characters that unite the Sepiidae and the Sepiolida and are considered to be apomorphic (newly derived) characters are (characters 3 and 5 seem to be independently derived in a few Myopsida):
- Eyes with secondary eyelids.
- Funnel with lateral adductor muscles.
- Mantle locking-apparatus that does not reach the mantle margin.
- Absence of an interstellate connective.
- Gills without a branchial canal
About This Page
National Museum of Natural History, Washington, D. C. , USA
Richard E. Young
University of Hawaii, Honolulu, HI, USA
Page copyright © 2004 and Richard E. Young
- First online 18 August 2004
- Content changed 10 December 2006
Citing this page:
Vecchione, Michael and Young, Richard E. 2006. Sepioidea http://tolweb.org/Sepioidea/23870/2006.12.10 in The Tree of Life Web Project, http://tolweb.org/
. Version 10 December 2006 (under construction).