Family : Charoniidae
Text © Dr Domenico Pacifici
English translation by Mario Beltramini
Present in Atlantic and in tropical and temperate Indo-Pacific, Charonia variegata is found in the Mediterranean along the Greek and Turkish coasts © levend
Charonia variegata (Lamarck, 1816) is a marine gastropod mollusc belonging to the family Charoniidae.
This species is known also with the evocative name of Atlantic triton or Atlantic triton’s trumpet in honour of the son of Poseidon, king of the sea, often portrayed with a shell in his hand used as trumpet to calm storms. Originally, in fact, the name was Triton variegatum but was changed in Charonia in 1969 by Johannes Gistel because the term “Triton” had become polysemic, that is having a number of meanings.
The name of the genus Charonia comes from the Roman name Charon, in old Greek “χαροπός”, a famous mythological character who carried the souls of the dead across the Styx, the river of the Underworld. The name of the species variegata comes from the Latin “variegatus” = spotted, variegated, in reference to the livery of the animal.
It’s an impressive mollusc who can reach 40 cm and moves usually on bottoms between 5 and 20 m of depth, but has been also found at 100 m © Falk Viczian Solarboot-Projekte gGmbH
Zoogeography
To the genus Charonia belong at least four species, distributed in the temperate and tropical seas: Charonia lampas (Linnaeus 1758), diffused in the tropical waters of the Atlantic, Indian and Pacific oceans, and in the western Mediterranean; Charonia marylenae Petuch & Berschauer, 2020, with distribution limited to southern Brazil; Charonia tritonis (Linnaeus, 1758), the biggest species and with the amplest geographical distribution extending across the Indo-Pacific tropical region; Charonia variegata, separated from the previous under the genetic and geographical profiles due to the upheaval of the isthmus of Panama during the late Pliocene (3,3-3,0 Ma), and distributed in the Atlantic Ocean, from North Carolina to the coasts of Brazil. It is less common in the Atlantic which borders north-west Africa, the Canary Islands, Madeira, Cape Verde and St. Helena.
The spires are marked and irregular and the operculum lips have white transversal nail shaped bands called teeth © Laurent Fey
In the Mediterranean Sea this mollusc has colonized the Greek shores, extending along the entire coast of Turkey and Cyprus, although according to some authors the Cypriot populations could belong to the species Charonia seguenzae (Aradas & Benoit, 1871).
Ecology-Habitat
Charonia variegata prefers shallow waters, with a bathymetric range between 5 and 20 m even if, in quite rare instances, specimens have been found at more than 100 m of depth, showing the amazing adaptability of this species.
It can be found in the phanerogams prairies, in the coral reefs and particularly on seaweeds, boulders, corals, rocks and sand.
Characteristic are the yellow black striped tentacles with olfactory-sensory function. They help eyes in hunting and smell the approach of possible predators © Brian Cole
It is a voracious nocturnal predator and feeds mainly on echinoderms, i.e. sea urchins and seastars, but occasionally also on holothurians like the sea cucumbers.
It catches the prey with its strong foot and pierces its dermis with the radula injecting a paralyzing saliva and sucking its inner substance with the radula, the rasping tongue typical of gastropods.
For the ingestion and digestion of the prey also several days are necessary, but in some cases,seen the modest size, is able to even ingest small whole molluscs.
Morphophysiology
In Caribbean has blocked an Oreaster reticulatus with the foot. Piercing the dermis has injected in this big starfish a paralyzing saliva and now sucks its inside © Brianna Tracy-Sawdey
The shell of this mollusc is impressive and may reach a maximum length of 40 cm. Of tapered shape and with a pointed cusp, the shell has a variegated colouration of shades ranging from creamy white to dark brown, and, occasionally, orange or golden.
The spires are marked and irregular and the lips of the operculum are covered with transverse nail-shaped bands, white in colour, called teeth. The body of the animal is yellow spotted with light brown patches scattered throughout the body.
Quite characteristic are the tentacles, yellow with black stripes, present on the head, with olfactory-sensory function, intended for hunting or for perceiving predators nearby.
In Mediterranean, in Spain, the prey on duty is a Paracentrotus lividus, sea urchin very frequent along the coasts © Susanne Spindler
Ethology-Reproductive Biology
Unlike many gastropod molluscs, this species is not hermaphroditic but has separate sexes and the reproduction takes place via internal fecundation. When the fecundation has been done, the female lays about one hundred drop-shaped eggs sticking them on a rock face or on a well sheltered cavity.
Several recent studies have shown how the female keeps in touch with its brood during the whole period of development of the eggs. After about three or four weeks the eggs hatch releasing the larvae in free waters. The larvae have a development of more than three months and are of type “veliger”. This is a larval form typical of the gastropods characterized by a small shell surrounding the visceral organs and by a ciliated “velum” utilized for swimming and the collection of the surrounding particulate.
Two specimens side by side. Operculum is raising and surely not to prey. Unlike many gastropods Charonia variegata is not hermaphroditic but has separate sexes and reproduction occurs by internal fecundation. The female lays about one hundred drop shaped eggs sticking them on a rocky wall or a cavity on the bottom © Ben Hutchins
In some areas of the world, like in Guadeloupe, Charonia variegata is used for food purposes and consequently has been established a minimum catching size of 25 cm.
The populations of the species of Charonia, abundant in the past, are in numerical decline if not completely extinct in many geographical areas, especially due to their excessive collection. At present, though not appearing in the IUCN Red List, Charonia variegata is however protected by the Attachment II of 1979 Berne Convention and by Barcelona 1999 Convention.
Synonyms
Charonia tritonis variegata Lamarck, 1816; Triton variegata Lamarck, 1816; Triton atlantica Bowdich, 1822; Tritonium sulcatum Risso, 1826; Charonia tritonis nobilis Conrad, 1849; Triton nobilis Conrad, 1849; Tritonium commutatum Kobelt, 1876.
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