Home|Search|Identify|Taxonomic tree|Quiz|About this site|Feedback
Developed by ETI BioInformatics
Characteristics, distribution and ecology
Taxonomische classification
Synonyms and common names
Literature references
Images, audio and video
Links to other Web sites

Cymbulia peroni De Blainville, 1818c morpha peroni De Blainville, 1818c

Overview

This is a shell-less pteropod with a large gelatinous slipper-like pseudoconch, 5.6 cm long. The wings are disc-shaped and the visceral mass forms a dark nucleus embedded in the perfectly transparent pseudoconch. The pseudoconch is blunt and covered with cusps. It is an elegant swimmer that feeds by means of a mucous web in microplankton. It is found throughout the Mediterranean and adjacent Atlantic Ocean (Cymbulia p. peroni 1).

Taxonomic Description

Pseudoconch (Cymbulia p. peroni line drawing) with a blunt anterior top, covered with spines arranged in rows, some spines are irregularly placed between the rows (Cymbulia p. peroni, Cymbulia p. peroni pseudoconch stained). The spines near the border of the shoe-shaped cavity in the pseudoconch are larger than the other ones and asymmetrical (Cymbulia p. peroni dorsal, Cymbulia p. peroni swimming). The animal has a colourless heart-shaped swimming plate, while in the middle of the posterior margin a wing lobe with a long filamentous tentacle projects outwards. At the outer wing border two transparent spots, without muscles are found, the muscle fibres are fused (Cymbulia p. peroni wing muscles). The radula formula is 1-1-1 and the teeth are degenerate, the jaw is relatively small (Cymbulia p. peroni radula).
The length of the pseudoconch is up to 65 mm.

Morphology and Structure

The proboscis and the whole field between median and lateral footlobes is ciliated. The mouth, at the bottom of the proboscis, opens into a reduced buccal apparatus. The reduced radula is supported by a degenerate odontophore. The salivary glands are also reduced. Muscles are still present around the radula sac. The structure of the muscles under the radula connected with the odontophore indicates that their original function was the protrusion of the odontophore. The buccal mass is surrounded by longitudinal and circular muscles and is covered with a folded ciliated epithelium. Digestive diverticula and a style sac are attached to the stomach, caudally to the gizzard. The well developed gizzard is lined throughout by a chitinous cover, which is raised to form numerous pointed teeth (Cymbulia p. peroni gizzard plate). The pattern of these teeth is formed by a ring of; small anterior teeth, two large dorso-lateral teeth, two large ventro-lateral teeth and a smaller median tooth. The gizzard chitin is attached to the underlying epithelium by strands. The style sac produces a hyaline secretion. The opening of the style sac is not directed towards the gizzard. Two impressions, the left and right typhlosole, are seen in the wall of the style sac. The style is continuously present in the sac. The style sac is identical in Limacina and Cymbulia. As in many other Thecosomata the gizzard plates are an indication that the food consists of planktonic animals with hard skeletons. Phagocytes, which have a role in the digestion of hard material in the Lamellibranchia, are absent in Cymbulia. The gizzard-stomach complex also seem to have a sorting function besides a mechanical function, directing nutritive material towards the diverticula and the roughage towards the intestine. The gut is wholly lined with ciliated epithelium except for the buccal mass and gizzard. A circular and a longitudinal muscle layer surround the gut except for the intestine so that transport is possible by ciliar movements as well as by peristaltics. Mucous glands are located in the oesophagus. Three types of liver cells surround the digestive diverticula: a) an absorption type with vacuoles, b) the smaller secretory type, and c) the third type showing stages of division.
The chromosome number is 34 (2N) (Thiriot-Quievreux, 1988)

Juveniles

The veliger has a velum with four lobes, the larval shell has 1.5 whorls (max. diam. 0.72 mm), the last one increasing rapidly in width. The opercular lobe between the two parapodia or wings is hyaline (Thiroit-Quiévreux, 1970).

Reproduction

The species is a protandric hermaphrodite. The chromosome number N=18, but a diploid number of 32 is also found. Spermatogenesis in the present species shows two types of spermatozoids which have different development. It is not shown if these two types are also functionally different.

Ecology

The species is a phytophagous mucus feeder. In Adriatic specimens, diatoms, flagellates, a few heteropods, copepods and chaetognath fragments were found. The same food was found in Cymbulia p. morpha minor. The temperature range is 13.0°C to 27.0°C; the salinity range is up to 38.57 %oS. The vertical depth range of this species is found between 150 and 2000 m. Rampal (1967) found specimens between 1000 and 2000, and juveniles at a depth of 600 meters.
Larvae are found in February in the Bay of Banyuls and Alger. First a veliger develops with a four lobed velum, each lobe with brown or reddish spots; the velum measures 2.8 mm. The shell, with one and a half whorls is 0.72 mm in diameter. Before metamorphosis the velum is hexalobular. When metamorphosis is reached the wings start to develop. The operculum bearing foot section grows larger and at both sides two smaller lobes with yellow terminal points develop. The velum and the two lateral lobes are lost at the same time. During metamorphosis the larval heart is lost. When the shell is lost the soft parts measure 2.1 mm and they have a caudal appendage of 3 mm. Besides the loss of the larval organs, metamorphosis is characterised by the transformation of larval organs like the parapodium (into the wings), the operculigerous lobe (into the median appendage), and the posterior oesophagus (into the gizzard). Moreover, new organs occur such as the connective tissue above the eyes and the pseudoconch. The mantle gland has developed from a fold at the right side of the mantle in the larval stage. In adults horizontal swimming speed is 11.9 mm/sec., upward swimming is 10.3 mm/sec and sinking speed is 9.0 to 12.3 mm/sec.

Distribution

This form is found in the Mediterranean and sometimes in the W-Atlantic. This species shows some resemblance to some Peraclis species in their restriction to Atlantic and Mediterranean. The only remarkable aberration is the penetration of this species into the Mozambique Current, see the Cymbulia p. peroni map. This extension into the MAD centre is also known for Atlantic species in other plankton groups.

Types

Cymbulia peroni forma peroni De Blainville, 1818: 333.
No types found in MHNP.

Cymbulia peroni peroni