Carinaria Lamarck 1801

Introduction

The body is basically cylindrical and elongated, consisting of proboscis, trunk and tail regions. The stalked visceral nucleus and swimming fin are opposite each other on the posterior portion of the trunk. The visceral nucleus and gills are covered by a laterally compressed, cap-shaped shell. Tail size and shape are variable. A tail crest is present that varies in height, shape, and presence of pigmentation. The swimming fin is well developed and, in both sexes, has a small sucker on its postero-ventral margin. Only two of the species of Carinaria (C. lamarcki and C. challengeri) have a cosmopolitan distribution; three others (C. cithara, C. cristata and C. galea) are absent from the Atlantic Ocean, i.e. are Indo-Pacific; while one species, C. japonica is restricted to the Transition Zone Faunal Province in the North Pacific Ocean.

Brief Diagnosis

Carinariid heteropods with:

• Body consists of a short proboscis, well-developed trunk, and a tail of varied size, shape and pigmentation
  
• Visceral nucleus stalked and covered by a laterally compressed, cap-shaped shell
• Visceral nucleus and swimming fin on posterior part of trunk
• Swimming fin with small sucker on ventro-lateral margin
  

Characteristics

1. Body morphology
   1. Body of varied length and cylindrical, proboscis short, trunk large and with a thick cutis, and tail of varied size, shape and length
      
   2. Visceral nucleus stalked; stalk of variable length
   3. Swimming fin on posterior part of trunk
   4. Tail of variable shape and size, with a low to tall dorsal crest
      

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      Figure. The three body regions and selected body parts in Carinaria japonica.

   5. Eye shape triangular (see figure below), except in C. cithara where the shape is cylindrical (Okutani, 1961)
      
   6. Pair of tentacles located immediately anterior to eyes, often with the right one reduced or vestigial
      
      

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      Figure. Left tentacle anterior and medial to the left eye in Carinaria galea.

2. Shell
   1. Shell moderately compressed laterally and cap-shaped, with a flattened keel projecting from the anterior margin
   2. Height and length (at the aperture) of shell, and height of keel variable
      
      

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      Figure. Shell covering stalked visceral nucleus and gills in Carinaria galea (left) and C. lamarcki (right). Keel produced from anterior margin of shell; tall in C. galea and low in C. lamarcki

3. Swimming fin and sucker
   1. Swimming fin well developed
   2. Fin sucker located on postero-ventral margin of swimming fin
      

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      Figure. Swimming fin and postero-ventral sucker in Carinaria japonica, viewed from right side of body.

      4. Larvae with long, ciliated arms that serve for locomotion and feeding (see photograph by Jackie Sones below)

Comments

The genus Carinaria includes six species, which can be distinguished by the following characters:

References

Okutani, T. 1961. Notes on the genus Carinaria (Heteropoda) from Japanese and adjacent waters. Publications of the Seto Marine Biological Laboratory 9: 333-352.

Richter, G. and R. R. Seapy. 1999. Heteropoda, pp. 621-647. In: D. Boltovskoy (ed.), South Atlantic Zooplankton. Backhuys Publishers, Leiden.

Tesch, J. J. 1949. Heteropoda. Dana Rept. No. 34, 53 pp., 5 plates.