Beaked larva
[this juvenile, not belonging to the pelagic molluscs, is included as it is frequently mistaken for a pteropod]

Overview

This is a shelled larval snail (not a pteropod) up to 0.1 cm long, with a semi-transparent uncoiled shell. The cross-section is round. The surface has transverse rings. The shell is long and narrow, tube-shaped, straight and not tapering towards the end. The mouth rim is not continuous as an anchor-shaped tooth projects. It lives in warm waters in the upper layers of all oceans (Beaked larva).

Taxonomic Description

Shell straight with distinct broad transverse ribs that are of equal strength over the entire shell length. The lateral sides of the shell are parallel so that the shell diameter is the same at all levels. Aperture oval with beak (Beaked larve aperture). Embryonic shell oval not sharply separated off from the teleoconch. The soft parts in the preserved specimens occupy about 2/3 of the shell volume. At the top of the body a bilobed velum, 0.1 mm long, is found in between a small footlobe. The animal is fixed obliquely to the shell by 6 columellar muscle fibres each about 0.15 mm long. The greater part of the body consists of interstitial tissues indicating that they are juvenile specimens.
Shell length 0.8 - 1.2 mm width ±0.1 mm, the relatively large embryonic shell is 0.25 mm long.

Juveniles

This is a juvenile itself.

Others

Chen (1962) pictured this species under the name Creseis chierchiae and probably did not distinguish between real Creseis chierchiae specimens and the present species. Frontier (1963b) described this species as resembling Creseis acicula given by Tokioka (1955) and as representing a yet undescribed new species. Richter (1976) stated that this species does not belong to Creseis and that it could even not belong to the Gastropoda, but no further arguments were given. Frontier (1963) considered this species, figured by Menzies (1958) to be a pteropod, probably of the genus Creseis but did not consider it to be Creseis chierchiae. McGowan (1960) places 'Beaked larva' and Creseis chierchiae together but he mentioned the differences between the two, especially with regards the embryonic shell.

Types

Not relevant.

Kingdom Animalia
Phylum Mollusca
Class Gastropoda
Subclass Euthyneura
Order Thecosomata
Suborder Euthecosomata
Family Cavoliniidae
Subfamily Clioinae
Genus Beaked
Species Beaked larva

Status in World Register of Marine Species

Not included in WoRMS database

Scientific synonyms and common names

Beaked larva

sometimes confused with:
Creseis chierchiae (Boas, 1886) in Menzies, 1958 and in McGowan, 1960

Haagensen, D. A., 1976 Caribbean zooplankton. Part II. Thecosomata. Off. Nav. Res. Dept. of the Navy. U. S. Govt. Print Off. Washington D. C.: 551-712.

Menzies, R. J., 1958. Shell-bearing pteropod gastropods from mediterranean plankton (Cavoliniidae). Pubbl. Staz. Zoologica Napoli 30 (3): 381-401, 5 tabs, 9 figs, 8 maps.

Spoel, S. van der and Newman, L., 1990. Juveniles of the pteropod Hyalocylis striata (Mollusca, Gastropoda, Pteropoda). Basteria 54: 203-210, figs 1-6.

No distribution map was available at OBIS the last time we checked. Retry now.

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