Note

Cephalopoda Glossary

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Fin sizes: Fins of decapodiforms very greatly in both length and width. Fin lengths range from over 100% of the ML to less than 10% of the ML. We arbitrarily define «long» fins as more than 75% of the ML and «short» fins as less than 25% of the ML. In the figure below, "A" has short fins and the others have long fins. Most squids have fins of intermediate size. Some squids (not shown) have fins posterior to the muscular mantle.

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Fin shapes: Shapes are difficult to define as the shape of some fins bridge the gaps between standard shapes. Use these definitions cautiously.

Sagittate fins

Sagittate fins are probably the most common shape found in squids. These fins have anterior free fin-lobes, a relatively sharp lateral angle and posterior elongate fin with a concave posterolateral margin.

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Rhomboid fins

Rhomboid fins are similar to sagittate fins except that the posterolateral fin margin is not concave but straight.

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Circular/elliptical fins

Circular/elliptical fins lack posterior fin-lobes, have or lack anterior fin-lobes and and have broadly rounded or no lateral fin angles. The circular to elliptical outline describes the shape of the combined fins.

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Lanceolate fins

Lanceolate fins are elongate in the anterior-posterior direction, lack posterior fin lobes, usually have reduced anterior fin lobes and lack a lateral angle. The resulting shape is similar to the head of a lance.

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Ear-shaped fins

Ear-shaped fins have both anterior and posterior fin lobes and lack lateral angles. The fins often are completely separate from one another.

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Lobate fins

Lobate fins have a posterior fin-lobe and lack an anterior one. No lateral angle exists and each fin is often much longer than broad.

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Ribbed fins

Ribbed fins have a series of independent muscle bundles within each fin that look like a series of ribs or teeth on a comb. The fin is long and slender and without lateral angles.

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Skirt-like fins

Skirt-like fins are narrow and extend along the lateral margins of the mantle. They have free anterior and posterior lobes and lack lateral angles..

References

Chun, C. 1910. Die Cephalopoden. Oegopsida. Wissenschaftliche Ergebnisse der Deutschen Tiefsee-Expedition, "Valdivia" 1898-1899, 18: 1-522 + Atlas.

McSweeny, E. S. 1978. Systematics and morphology of the Antarctic cranchiid squid Galiteuthis glacialis (Chun). Antarctic Research Series, 27: 1-39.

Okutani, T. 1981. Two new species of the squid genus Onykia from the tropical Indian Ocean (Cephalopoda, Onychoteuthidae). Bull. Nat. Sci. Mus., Tokyo, Ser. A. 7: 155-163.

Pearcy, W. G. and G. L. Voss. 1963. A new species of gonatid squid from the Northeastern Pacific. Proc. Biol. Soc. Wash., 76: 105-112.

Roper, C.F.E. 1969. Systematics and zoogeography of the worldwide bathypelagic squid Bathyteuthis (Cephalopoda: Oegopsida). Bulletin of the United States National Museum, 291:1-210.

Roper, C. F. E., R. E. Young and G. L. Voss (1969). An illustrated key to the families of the order Teuthoidea. Smiths. contr. zool., 13:1-32.

Voss, G. L. 1963. Cephalopods of the Philippine Islands. Bull. U. S. Nat. Mus., 234: 1-180.

Young, R. E. 1972. The systematics and areal distribution of pelagic cephalopods from the seas off Southern California. Smithson. Contr. Zool., 97: 1-159.

Young, R. E. and C. F. E. Roper (1969). A monograph of the Cephalopoda of the North Atlantic: The family Cycloteuthidae. Smithson. Contr. Zool., No. 5: 1-24.

Young, R. E. and C. F. E. Roper (1969). A monograph of the Cephalopoda of the North Atlantic: The family Joubiniteuthidae. Smithson. Contr. Zool., No. 15: 1-10.