Under Construction

This is an archived version of a Tree of Life page. For up-to-date information, please refer to the current version of this page.

This genus contains the following 12 species:

Containing group: Gonatidae

Introduction

Gonatus, the most speciose genus in the family, has its highest diversity in the high North Pacific. These squids reach a maximum length of 39 cm ML.

Diagnosis

A gonatid ...

• with one or more hooks in median line on tentacular club.

Characteristics

1. Arms
1. Hooks in medial two armature series on arms I-III.
   
   
2. Tentacles
1. Tentacles present in subadults.
2. Tentacular club with one or more hooks in median line; one greatly enlarged.
3. Proximary locking-apparatus of club with suckers and knobs medial to 4-6 large ridges and grooves, and usually several smaller ones.
   image info

   Figure. Oral view of tentacular club of G. californiensis, 315 mm GL, immature female, preserved. Photograph of preserved club by R. Young.

3. Head
1. Radula with 5 teeth in transverse row.
   
   
4. Mantle
1. Mantle tissue muscular or flabby depending on species.
   
   
5. Fins
1. Fins sagittate, drawn out posteriorly into a short tail.
   
   
6. Photophores
1. Ocular photophores present only in G. pyros.

Comments

Many of the species characteristics are found on the tentacles. The tentacles are complex and for descriptive purposes the club and stalk are divided into various zones, regions and series as follows:

The following table compares some characteristics of subadult species of Gonatus. The most useful character states are indicated in bold-red. The table doesn't separate all species.

Species / Character	Habitat	Ocular light organs	Proximal club hooks	Distal club hook	Medial suckers of tentacular stalk	Suckers on club	Club suckers of dorsal- and ventral marginal zones merge proximally.	Arm II< III length	Club length
G. antarcticus	Antarctic waters	No	Yes	Yes	120-140	250-315	No	40-50% ML	16-17%  ML
G. berryi	North Pacific	No	Yes	Yes	0-2	159-181	No	60-70% GL	30-37% GL
G. californiensis	North Pacific	No	Yes	Yes	40-80	215-270	No	46-53% GL	17-24% GL
G. fabricii	North Atlantic	No	Yes	Yes	38-109	155-229	No	53-59% GL	12-20% GL
G. madokai	North Pacific	No	Yes	Yes	Many	?	Yes	90% ML	20% ML
G. middendorffi	North Pacific	No	No	Yes	Few	?	No	50% ML	10% ML
G. onyx	North Pacific	No	No	No	0-27	160-200	No	48-54% GL	20-25% GL
G. oregonensis	North Pacific	No	Yes	Yes	70	295-370	No	59-63% ML	21-30% ML
G. pyros	North Pacific	Yes	Yes	Yes	50-125	151-184	No	60-70% GL	20-25% GL
G. steenstrupi	North Atlantic	No	Yes	Yes	75-165	190-225	No	50-70% GL	20-36% GL
G. ursabrunae*	North Pacific	No	?	?	?	?	?	42-56% ML	13-25% ML

 *Known only from juveniles but with distinctive relative sucker sizes on arms and club dactylus.

 

Life History

Brooding of egg masses in G. onyx (Seibel et al., 2000) [suspected in G. fabricii (Bjorke et al., 1997)] occurs in deep water. Such brooding behavior, rare in oceanic squids, may prove to be characteristic of all members of the genus and perhaps the entire family. The long brooding period demanded by cold temperatures in deep water and its resulting slow population turnover rate, presumably is offset, in evolutionary time, by low egg mortality in the vast, dark, lowly populated bathypelagic environment (see Seibel, et al., 2000). For more information on brooding behavior, go to the G. onyx page.

References

Nesis, K. N. (1982). Abridged dey 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.

Okutani, T. and M. R. Clarke (1992). Family Gonatidae Hoyle, 1886. P. 139-156. In: Sweeney, M. J., C. F. E. Roper, K. M. Mangold, M. R. Clarke and S. V. Boletzky (eds.). "Larval" and juvenile cephalopods: a manual for their identification. Smiths. Contr. Zool., No. 513.

Seibel, B. A., F. G. Hochberg, and D. B. Carlini. 2000. Life history of Gonatus onyx (Cephalopoda: Teuthoidea): deep-sea spawning and post-spawning egg care. Marine Biology 137 (3): 519-526.

Seibel, B. A., B. H. Robison and S. H. D. Haddock. 2005. Post-spawning egg care by a squid. Nature 438: 929.