Cephalopoda: Origin of the Term Occipital Region

Richard E. Young, Michael Vecchione and Katharina Mangold

Structures on the back of the head are known by a variety of names. The transverse ridge that extends from one side of the funnel groove around the back of the head to the other side of the funnel groove is known as the olfactory crest (e.g., Williams, 1909) due to the nearby postion of the olfactory organ, the anterior transverse fold of the neck (Naef, 1921-23), and the nuchal crest (e.g., Young, 1972) but with little present consensus. However none of these terms is appropriate. The olfactory organ is a small structure that is not on the crest; cephalopods have no true neck and the nuchal region is only the posterodorsal region of the head. As a result, we propose here the term occipital region for the back of the head and occipital crest, occipital folds (often called neck folds or nuchal folds or olfactory folds) and occipital membrane (= anterior transverse fold of the neck) for structures located in this region. According to the Random House Dictionary of the English language, occiput is the back of the head or skull. Thus, we are borrowing from vertebrate terminology.

References

Naef, A. 1921-23. Cephalopoda. Fauna und Flora des Golfes von Neapel. Monograph, no. 35. English translation: A. Mercado (1972). Israel Program for Scientific Translations Ltd., Jerusalem, Israel. 863pp., IPST Cat. No. 5110/1,2.

Williams, L. W. 1909. The anatomy of the common squid Loligo pealii, Lesueur. E. J. Brill, Leiden. 92pp., 3 pl.

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