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Carinaria lamarcki forma lamarcki Péron and Lesueur, 1810

Overview

This is a very large shelled pelagic snail, up to 22 cm long, with an almost completely transparent body. The body can never withdraw into the shell. The shell is low conical with a high keel. 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 the upper layers of the warm waters of all oceans(Carinaria l. lamarcki shell 2).

Taxonomic Description

The calcareous, transparent shell only covers the visceral nucleus and is frequently lost in collections. The shell is broad pyramidally-shaped with the protoconch, the only part with whorls, on top (Carinaria l. lamarcki shell). The body whorl is large with coarse transverse striation. The visceral nucleus is found on a very short stalk (Carinaria l. lamarcki intestine). The rounded dorsal fin is found opposite the nucleus with a fin sucker in both sexes (Carinaria l. lamarcki, Carinaria l. lamarcki drawing, Carinaria l. lamarcki 1). The muscle bundles in the fins are well separated. A thick gelatinous cutis surrounds the trunk. Tubercles frequently cover the cutis. The tail is similar to the trunk, transparent, with a ventral tail keel and an unpigmented clasper.
Tesch (1949) described, as an exception, in this family two spiral lines of sculpture on the embryonic shell of C. cithara. In some specimens three, short spiral lines are found on the second whorl. The embryonic shell consists of about 4 whorls and is completely planorboid. The teleoconch begins with a strong widening and forms 1/4 of a whorl. The eyes, with relatively small lens, are broad based and triangular in shape. Two tentacles are present and the right one is the largest. The visceral nucleus reflects the shape of the shell being, broader than high, triangular with numerous gills directed towards the body. The Carinaria l. lamarcki radula formula is 2-1-1-1-2. The radula (Carinaria l. lamarcki radula 1) shows a tricuspoid median plate.
Maximum body length 220 mm.

Juveniles

The juveniles have a small, dextrally coiled shell. There are 4 whorls (Carinaria l. lamarcki line drawing), the spire is high. There are sometimes 2 spiral lines on one entire larval whorl. The width of the last whorl is 1/3 of the shell diameter. The velum has 6 lobes with brown rim, each with one brown spot. The tentacles are colourless. The mantle is brown. The operculum is rounded in outline and shows a clear spire with growth lines. It is composed of two separate 'blades', a small inner and a larger outer one connected to each other in the centre (Carinaria l. lamarcki protoconch, Carinaria l. lamarcki juv.).

Reproduction

In this species the sexes are separate.

Ecology

This species is carnivorous and epipelagic.

Distribution

It is a cosmopolitan species with a wide north-south range between 60°N and 45°S. In the Mediterranean it is common everywhere and penetrates deep into the Caribbean. In the N-Atlantic a greater abundance is found than in the southern part which also occurs in species of the genus Atlanta. Only few data are available for the Indo-Pacific Ocean. Its absence or scarcity in the Indo-Malayan area is also typical. Specimens collected in this Archipellago probably originated from the W-Pacific, see the Carinaria l. lamarcki map. The forma challengeri, like the forma lamarcki, is found in all oceans as well as the Mediterranean; records are still scarce.

Geological Record

In the Boreal it occurs in the Adriatic Sea.

Types

Carinaria lamarcki Péron and Lesueur, 1810: 69, pl. 3, fig. 15.
Types were not found confirmed in MHNP, but shells are present which may have to be considered the types.

Carinaria lamarcki lamarcki