Abralia
Richard E. Young and Kotaro TsuchiyaThis tree diagram shows the relationships between several groups of organisms.
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close boxIntroduction
Species of Abralia are small squid some of which are associated with shallow bottoms on steep slopes and as such are members of the mesopelagic-boundary fauna.
Brief diagnosis:
An enoploteuthid ...
- without large, black photophores at the tips of arms IV (see, however, A. astrolineata).
- with fins extending to posterior tip of tail.
Characteristics
- Arms
- Arm suckers present distally on Arms IV.
- Arm suckers present distally on Arms IV.
- Tentacles
- Manus of club with one series of hooks; two series of suckers.
- Manus of club with one series of hooks; two series of suckers.
- Buccal crown
- Typical chromatophores on oral surfaces of buccal crown.
- Typical chromatophores on oral surfaces of buccal crown.
- Photophores
- Enlarged photophores on tips of arms IV generally absent; if present, not covered by black chromatophores (exception in A. astrolineata).
- Five to twelve photophores on each eye.
- Complex photophores of integument without red-colored filters.
Comments
Figure. Ventral view of arm IV integumental photophores of A. trigonura, off Hawaii. Photograph by R. Young.
In life, the integumental photophores have a characteristic appearance. The photo shows the three types of integumental photophores. A "lensed" photophore (white arrow) has a blue color and white ring. A "simple" photophore (black arraow) is small and violet-colored. The remaining are "complex" photophores and have a central green color and small "satellite" green-color points. Often complex photophores will appear blue rather than green depending on their physiological state (see Young and Arnold, 1982). The black dots are chromatophores.
The structure of a complex photophore can be seen here.
Classification
Species of Abralia are generally placed into six subgenera but these may not all be natural groups. The following table (modified from Tsuchiya and Okutani, 1988) shows the primary taxonomic features of each group.
Abralia (Abralia) | Abralia (Asteroteuthis) | Abalia (Astrabralia) | Abralia (Pygmabralia) | Abralia (Heterabralia) | Abralia (Enigmoteuthis) | |
No. distal sucker series on arms I-III | 3-4 | 3-4 | 2 | 2 | 2 | 2 |
Which arm IV hectocotylized | Right | Left | Right | Right | Left | Right |
No. Club hooks | >4 | <5 | >4 | <4 (often 1 or 2) | <5 | >5 |
Types of ocular photophores* | 2 | 2 | 1 | 1 | 2 | 1 |
Large, unpigmented caudal and arm IV-tip photophores | No | No | Yes | No | No | No |
Attachment of buccal connective to arm III | Ventral | Ventral | Ventral | Ventral | Ventral | Dorsal |
References
Nesis, K. N. 1982. Abridged key to the cephalopod mollusks of the world's ocean. 385,ii pp. Light and Food Industry Publishing House, Moscow. (In Russian.). Translated into English by B. S. Levitov, ed. by L. A. Burgess (1987), Cephalopods of the world. T. F. H. Publications, Neptune City, NJ, 351pp.
Tsuchiya, K. and T. Okutani. 1988. Subgenera of Enoploteuthis, Abralia and Abraliopsis of the squid family Enoploteuthidae (Cephalopoda, Oegopsida). Bulletin of the National Science Museum, Tokyo (series A) 14: 119-136.
Young, R. E. and J. M. Arnold. 1982. The functional morphology of a ventral photophore from the mesopelagic squid, Abralia trigonura. Malacologia 23: 135-183.
Young, R. E., L. A. Burgess, C. F. E. Roper, M. J. Sweeney and S. J. Stephen. 1998. Classification of the Enoploteuthidae, Pyroteuthidae and Ancistrocheiridae. Smithsonian Contr. to Zoology, No. 586.
About This Page
Richard E. Young
University of Hawaii, Honolulu, HI, USA
Tokyo University of Fisheries, Tokyo, Japan
Page copyright © 2009 Richard E. Young and
Page: Tree of Life Abralia Authored by . Richard E. Young and Kotaro Tsuchiya. The TEXT of this page is licensed under the Creative Commons Attribution-NonCommercial License - Version 3.0. Note that images and other media featured on this page are each governed by their own license, and they may or may not be available for reuse. Click on an image or a media link to access the media data window, which provides the relevant licensing information. For the general terms and conditions of ToL material reuse and redistribution, please see the Tree of Life Copyright Policies.
- Content changed 26 July 2009
Citing this page:
Young, Richard E. and Kotaro Tsuchiya. 2009. Abralia http://tolweb.org/Abralia/19642/2009.07.26 in The Tree of Life Web Project, http://tolweb.org/
. Version 26 July 2009 (under construction).