''Tonna galea'', commonly known as the giant tun, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of marine

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

in the family

Tonnidae The Tonnidae are a family (biology), family of medium-sized to very large sea snails, known as the tun shells. These are marine invertebrates, marine gastropod molluscs in the clade Littorinimorpha. The name ''tun'' refers to the snails' shell sh ...

(also known as the tun shells). This very large

sea snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...

or tun snail is found in the

North Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Africa, Europe an ...

as far as the coast of

West Africa West Africa or Western Africa is the westernmost region of Africa. The United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Mali, Maurit ...

, in the

Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ea ...

and the

Caribbean Sea The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lanmè Karayib; jam, Kiaribiyan Sii; nl, Caraïbische Zee; pap, Laman Karibe) is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico ...

. The species was first described by

Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...

in 1758.

Description

The ventricose shell of adult ''Tonna galea'' is very large, with an average height of . Specimens of this species have been quoted of the size of a man's head. The shell is thin and inflated, but still relatively solid and durable. The shell is almost diaphanous when young; at that time the transverse ribs of the surface are only indicated by lines of a slightly deeper tint. In terms of its weight however, the thin shell is very much lighter than the shell of most other large sea snails. The

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An opt ...

of the shell is "distinctly round" and wide. The conical

spire A spire is a tall, slender, pointed structure on top of a roof of a building or tower, especially at the summit of church steeples. A spire may have a square, circular, or polygonal plan, with a roughly conical or pyramidal shape. Spires are ...

is formed of six convex, very distinct

whorl A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). Whorls in nature File:Photograph and axial plane floral ...

s, loaded externally with wide, flat, slightly raised ribs, separated by narrow and superficial furrows. The whorls of the spire are isolated by a deep channeled suture. The

body whorl The body whorl is part of the morphology of the shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk. In gastropods In gastropods, the b ...

is rounded and very ventricose. The

is large, subovate, colored interiorly with reddish, and marked with transverse ribs corresponding to the furrows without. The outer

lip The lips are the visible body part at the mouth of many animals, including humans. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech. Human lips are a tactile sensory organ, and can be ...

is dilated, undulated, tinged with black, or a deep brown upon the edge. The inner lip is whitish, spread out in a very thin plate upon the belly of the body whorl. The

columella Lucius Junius Moderatus Columella (; Arabic: , 4 – ) was a prominent writer on agriculture in the Roman Empire. His ' in twelve volumes has been completely preserved and forms an important source on Roman agriculture, together with the wo ...

is smooth, polished, and forms at the left of the umbilicus a thick rib, marked by transverse striae, which terminates at the emargination of the base. The external surface of this shell is of a uniform reddish fawn color ; nevertheless the ribs are varied with wide spots or irregular brown and white blotches which are very remarkable.Kiener (1840). General species and iconography of recent shells : comprising the Massena Museum, the collection of Lamarck, the collection of the Museum of Natural History, and the recent discoveries of travellers; Boston :W.D. Ticknor,1837
(described as 'Dolium olearium'') The animal is of a clear brownish red, without spots, and its tentacles are encircled, towards the point, with a wide reddish-brown ring. The foot beneath is of a dark violet, with the edge embroidered with deep brown. ''Tonna galea'' possess large

salivary gland The salivary glands in mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands (parotid, submandibular, and sublingual), as well as hundreds of minor salivary glands. Salivary gla ...

s. The structure of these glands was first described and detailed by Heinrich Weber in 1927. Furthermore, the giant tun is also a

luminescent Luminescence is spontaneous emission of light by a substance not resulting from heat; or "cold light". It is thus a form of cold-body radiation. It can be caused by chemical reactions, electrical energy, subatomic motions or stress on a cryst ...

species; this is an extremely rare characteristic among the

prosobranch Prosobranchia was a large taxonomic subclass of sea snails, land snails and freshwater snails. This taxon of gastropods dates back to the 1920s. It has however been proven to be polyphyletic (consisting of more than one lineage of descent). Gene ...

gastropods. The animal gives off light that is green-white in colour when it traverses through the water with its foot "well-extended".

Distribution and habitat

This large sea snail is found in the

(specifically the

Canary Islands The Canary Islands (; es, Canarias, ), also known informally as the Canaries, are a Spanish autonomous community and archipelago in the Atlantic Ocean, in Macaronesia. At their closest point to the African mainland, they are west of Morocc ...

and

Madeira ) , anthem = ( en, "Anthem of the Autonomous Region of Madeira") , song_type = Regional anthem , image_map=EU-Portugal_with_Madeira_circled.svg , map_alt=Location of Madeira , map_caption=Location of Madeira , subdivision_type=Sovereign st ...

), the

, the

, and in the waters off the coast of

Angola , national_anthem = " Angola Avante"() , image_map = , map_caption = , capital = Luanda , religion = , religion_year = 2020 , religion_ref = , coordina ...

Cape Verde , national_anthem = () , official_languages = Portuguese , national_languages = Cape Verdean Creole , capital = Praia , coordinates = , largest_city = capital , demonym ...

and

. The preferred habitat for this species is

seabed The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as 'seabeds'. The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...

s that are muddy or sandy with

seagrass Seagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and Cymodoceaceae), all in the orde ...

beds. In the Mediterranean, these snails are typically found at depths ranging from just beneath the surface to . ''Tonna galea'' has been placed on Annex II of both the

Berne Convention on the Conservation of European Wildlife and Natural Habitats The Bern Convention on the Conservation of European Wildlife and Natural Habitats, also known as the Bern Convention (or Berne Convention), is a binding international legal instrument in the field of Nature Conservation, it covers the natural ...

and the Protocol of the

Barcelona Convention The Convention for the Protection of the Marine Environment and the Coastal Region of the Mediterranean, originally the Convention for Protection of the Mediterranean Sea against Pollution,

Ecology

Information on the biology and life history of ''Tonna galea'' is scarce, due to the fact that the species has only rarely been studied. It is

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other sof ...

, and utilizes its two

proboscis A proboscis () is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular mouthparts used for feeding and sucking. In vertebrates, a proboscis is an elong ...

es—located on top of its head—to envelop its prey, which primarily consists of

sea cucumber Sea cucumbers are echinoderms from the class Holothuroidea (). They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. Sea cucumbers are found on the sea floor worldwide. The number of holothuria ...

s. To a lesser extent it also feeds on

sea urchin Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) of ...

starfish Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish ...

. fish,

bivalves Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

and

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

s. As a

defense mechanism In psychoanalytic theory, a defence mechanism (American English: defense mechanism), is an unconscious psychological operation that functions to protect a person from anxiety-producing thoughts and feelings related to internal conflicts and o ...

, the snail will squirt its highly-acidic saliva when disturbed. This contains approximately 2–5%

sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular formu ...

, which is used to kill its prey. The presence of this acid was recorded by

Franz Hermann Troschel Franz Hermann Troschel (10 October 1810 – 6 November 1882) was a German zoologist born in Spandau. He studied mathematics and natural history at the University of Berlin, where he was awarded his doctorate in 1834.Beolens, Bo; Watkins, Michael; ...

in 1854.

List of synonyms

This is a list of all the various scientific names that have been applied to this species over time. * ''Buccinum galea'' Linnaeus, 1758 (original combination) * ''Buccinum olearium'' Linnaeus, 1758 * ''Cadium galea'' (Linnaeus, 1758) * ''Cadus galea'' (Linnaeus, 1758) * ''Dolium (Dolium) galea'' (Linnaeus, 1758) * ''Dolium (Dolium) galea antillarum'' (Mörch, 1877) * ''Dolium (Dolium) galea'' var. ''brasiliana'' (Mörch, 1877) * ''Dolium (Dolium) galea'' var. ''epidermata'' (de Gregorio, 1884) * ''Dolium (Dolium) galea'' var. ''spirintrorsum'' (de Gregorio, 1884) * ''Dolium (Dolium) galea'' var. ''tardina'' (de Gregorio, 1884) * ''Dolium antillarum'' Mörch, 1877 * ''Dolium antillarum'' var. ''brasiliana'' Mörch, 1877 * ''Dolium epidermata'' de Gregorio, 1884 * ''Dolium galea'' (Linnaeus, 1758) * ''Dolium galea'' var. ''epidermata'' de Gregorio, 1884 * ''Dolium galea'' var. ''spirintrorsa'' de Gregorio, 1884 * ''Dolium galea'' var. ''spirintrorsum'' de Gregorio, 1884 * ''Dolium galea'' var. ''tardina'' de Gregorio, 1884 * ''Dolium galeatum'' Locard, 1886 * † ''Dolium modjokasriense'' Martin, 1899 * ''Dolium tardina'' de Gregorio, 1884 * ''Dolium tenue'' Menke, 1830 * ''Tonna (Tonna) galea'' (Linnaeus, 1758) * ''Tonna (Tonna) galea brasiliana'' (Mörch, 1877) * ''Tonna (Tonna) galea galea'' (Linnaeus, 1758) * ''Tonna galea abbotti'' Macsotay & Campos, 2001 * ''Tonna galea brasiliana'' (Mörch, 1877) * ''Tonna olearium'' (Linnaeus, 1758)

References

External links

* {{taxonbar, from=Q1548480 Tonnidae Molluscs of the Atlantic Ocean Molluscs of the Mediterranean Sea Gastropods described in 1758 Taxa named by Carl Linnaeus