Carinaria cristata forma japonica Okutani, 1955b

Overview

This is a very large shelled pelagic snail, up to 15 cm long, with an almost completely transparent body. The body can never withdraw into the shell. The shell is high conical. Only the broad triangular visceral nucleus is darkly pigmented. The large eyes, with black retina, and the mouth organs are clearly seen. The intestine is frequently full and visible. The body is long and cylindrical with one swimming fin. It hunts large prey such as fish, shelled pteropods and other heteropods. It lives in upper layers of the warm waters of the N-Pacific Ocean. (Carinaria c. japonica 1).

Taxonomic Description

The forma differs from Carinaria c. cristata in shell shape and the shape of the tail crest. The shell is perfect triangular with a top angle of 66° and nearly straight sides. The keel is low. The embryonic shell, with 4 whorls, has fine transverse striation, a narrow umbilicus and an elevated spire (Carinaria c. japonica). The juveniles have a rounded operculum with a central nucleus. The transverse striae on the protoconch are regular. The body has a rather thick cutis with several tubercles, especially on the ventro-lateral sides. The tail crest resembles Carinaria lamarcki by being slightly triangular. The posterior tail part is pigmented as in the forma cristata. The eyes are broad based and triangular. The fin is round and has a sucker in both sexes; the wing muscles are well separated. The tentacles are small and equal in shape and size.
Maximum body length is 80 to 158 mm; the shell is 15 mm high and 19.5 mm in diameter.

Juveniles

The juveniles have a small dextrally coiled shell. A special description is not available.

Reproduction

In this form the sexes are separate.

Ecology

This form is carnivorous and epipelagic. For this forma described predators are turtles and tuna (Okutani, 1961). It feeds on Euphausia larvae, Paracalanus parvus, Calanus spec. Oithona pulmifera, Amphipoda juveniles, Evadne spec., Sagitta bedoti and Thalassiothrix longissima. Thaliacea, chaetognaths and copepods form the predominate food sources.

Distribution

This form is found in the N-Pacific Ocean, for more information see the forma cristata, see the Carinaria c. japonica map.

Types

Carinaria japonica Okutani, 1955: 251, figs. 1-3.
Holotype: female preserved in Tkai Regional Fisheries Research Laboratory.
Type locality: 36°21'N 141°00'E.

Kingdom Animalia
Phylum Mollusca
Class Gastropoda
Subclass Streptoneura
Order Mesogastropoda
Superfamily Atlantacea
Family Carinariidae
Genus Carinaria
Species Carinaria cristata
Forma japonica

Status in World Register of Marine Species

Not included in WoRMS database

Scientific synonyms and common names

Carinaria cristata forma japonica Okutani, 1955b

Synonyms

Carinaria latidens ? Dall, 1919: 342
Carinaria lamarcki Dales, 1953: 1110
Carinaria japonica n. sp. Okutani, 1955b: 251
Carinaria (cristata var.?) japonica Okutani, 1961: 339
Carinaria cristata forma japonica Van der Spoel, 1972c: 557

Aron, W., 1960. Animals in the eastern North Pacific and its relationship to physical and chemical conditions. Univ. Wash. Dep. oceanogr. Tech Rep. 63: 65-154 .

Dales, R. P., 1953. The distribution of some heteropod molluscs off Pacific coast of North America. Proc. zool. Soc. London 122(4): 1007-1015, 7 figs.

Dall, W. H., 1919. Description of new species of Mollusca from the North Pacific Ocean in the collection of the United States National Museum. Proc. U. S. nat. Mus. 56(2295): 293-371.

McGowan, J. A., 1967. Distributional atlas of pelagic molluscs in the California Current region. CALCOFI Atlas 6: 1-218.

Okutani, T., 1955b. On a new species of Carinaria, C. japonica. Venus 18(4): 251-258, 3 figs.

Okutani, T., 1961. Notes on the genus Carinaria (Heteropoda) from Japanese and adjacent waters. Publ. Seto mar. biol. Lab. 9(2): 333-252.

Okutani, T., 1962. A supplementary note on the shell of Carinaria japonica. Venus 22(1): 12-13.

Okutani, T., 1965. Heteropoda and Thecosomata in the Kuroshio. Bull. Plankt. Japan 12: 37-39.

Seapy, R. R., 1974a. Distribution and abundance of the epipelagic mollusk Carinaria japonica in waters off southern California. Mar. Biol. 24: 243-250, 4 figs.

Seapy, R. R., 1980. Predation by the epipelagic heteropod Carinaria cristata forma japonica. Mar. Biol. 60: 137-146.

Seapy, R. R., 1986. The heteropod fauna of oceanic waters off Hawaii. West. Soc. Malac. 19: 9-13.

Seapy, R. R., 1990d. Sampling requirements for epipelagic heteropod molluscs. Amer. Malac. Bull. 8(1): 45-52.

Starobogatov, J. I., 1971. Ordo Thecosomata; ordo Gymnosomata; ordo Heteropoda. In: Polevoy Zool. Inst. Akad. Moscou. opredeliteli planktona (without page or figure numbers, not bound, mimiographed). [in Russsian]

Thiriot-Quievreux, C., 1973a. Observations de la radula des hétéropodes (mollusques, Prosobranchia) au microscope électronique a balayage et interprétation fonctionelle. C. R. Acad. Sci. Paris 276(D): 761-764, 1 pl.

Spoel, S. van der and Pierrot-Bults, A. C., 1979. Zoogeography of the Pacific Ocean. In: S. van der Spoel and A. C. Pierrot-Bults (eds). Zoogeography and diversity in plankton. Utrecht (Bunge Sci. Publ.): 293-327.

Spoel, S. van der, 1972c. Notes on the identification and speciation of Heteropoda (Gastropoda). Zool. Meded. 47: 545-560.

Spoel, S. van der, 1976c. Pseudothecosomata, Gymnosomata and Heteropoda. Bohn, Scheltema & Holkema, Utrecht. 484 pp. 246 figs.

Yamaji, I., 1991. Illustrations of the marine plankton of Japan. 3°Ed. Hoikusha Publ. Co. Ltd, Osaka.: 1-538.

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