Scotch bonnet (shell)
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The Scotch bonnet (''Semicassis granulata'') is a medium-sized to large
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
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 ...
, a
marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...
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 ...
mollusk 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 e ...
in the
subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...
Cassinae The Cassidae are a taxonomic family of medium-sized, large, and sometimes very large sea snails commonly called helmet snails or bonnet snails. These are marine gastropod mollusks in the superfamily Tonnoidea and the clade Littorinimorpha.Go ...
, the helmet shells and bonnet shells. The
common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...
"Scotch bonnet" alludes to the general outline and color pattern of the shell, which vaguely resemble a tam o' shanter, a traditional
Scottish Scottish usually refers to something of, from, or related to Scotland, including: *Scottish Gaelic, a Celtic Goidelic language of the Indo-European language family native to Scotland *Scottish English *Scottish national identity, the Scottish ide ...
bonnet or cap. The shell is egg-shaped and fairly large, in maximum dimension, with a regular pattern of yellow, orange or brown squarish spots. The surface sculpture of the shell is highly variable: the surface can be smooth and polished, have grooves, be granulated, or even be nodulose on the shoulder of the whorls. This species lives intertidally and subtidally on sandy substrates, and is found primarily in the tropical and subtropical Western
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 ...
, from
North Carolina North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and So ...
to
Uruguay Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...
. It is the most common species in this subfamily in
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
. A similar-appearing sea snail 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 Northern Atlantic Ocean, ''
Semicassis undulata ''Semicassis undulata'' is a Mediterranean species of medium-sized sea snail, a marine gastropod mollusc in the subfamily Cassinae, the helmet snails and bonnet snails. Taxonomy This taxon was previously sometimes referred to at subspecies ...
'', is currently considered to be a separate species. The exact
taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...
of ''Semicassis granulata'' has been unclear in the past: as well as the current combination, 38 other combinations and
synonyms A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...
exist. In the spring, the adult females of this species lay eggs in tower-shaped structures. The eggs hatch as
veliger A veliger is the planktonic larva of many kinds of sea snails and freshwater snails, as well as most bivalve molluscs (clams) and tusk shells. Description The veliger is the characteristic larva of the gastropod, bivalve and scaphopod ...
larvae, which can float in the
plankton Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...
for up to 14 weeks before settling onto the seabed as tiny snails. Crabs are a predator of this sea snail. After the death of the snails, if the shells are still intact they are often used by
hermit crab Hermit crabs are anomuran decapod crustaceans of the superfamily Paguroidea that have adapted to occupy empty scavenged mollusc shells to protect their fragile exoskeletons. There are over 800 species of hermit crab, most of which possess an a ...
s. In 1965, in the US, the Scotch bonnet shell was named as a state symbol of
North Carolina North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and So ...
, the first designation of a US state shell.


Etymology

;Scientific name The generic name is a combination of the
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
prefix ''semi'', meaning half, and noun ''cassis'', meaning
helmet A helmet is a form of protective gear worn to protect the head. More specifically, a helmet complements the skull in protecting the human brain. Ceremonial or symbolic helmets (e.g., a policeman's helmet in the United Kingdom) without protect ...
. The
specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...
of this
taxon In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
, ''granulata'', is derived from the Latin noun ''grana'' meaning grain. Here it is used in the
diminutive form A diminutive is a root word that has been modified to convey a slighter degree of its root meaning, either to convey the smallness of the object or quality named, or to convey a sense of intimacy or endearment. A (abbreviated ) is a word-formati ...
, meaning granulated, or covered in granules, i.e. small grains or pellets, referring to the shell sculpture. ;Common name The shell of this species was given the
common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...
"Scotch
bonnet A Bonnet is a variety of headgear, hat or cap Specific types of headgear referred to as "bonnets" may include Scottish * Blue bonnet, a distinctive woollen cap worn by men in Scotland from the 15th-18th centuries And its derivations: **Feath ...
" because of a vague resemblance to a tam o' shanter, a traditional
tartan Tartan ( gd, breacan ) is a patterned cloth consisting of criss-crossed, horizontal and vertical bands in multiple colours. Tartans originated in woven wool, but now they are made in other materials. Tartan is particularly associated with Sc ...
hat which used to be commonly worn in Scotland. The shell has a regular pattern of square or rectangular patches that are orange, tan, or brown in color. The shell can sometimes be smooth except for growth lines, but in other individuals it can have a sculpture of incised spiral grooves and even weak axial ribs which, together with the colored patches on the shell, create an effect that is reminiscent of the pattern of a Scottish plaid.


Taxonomy

This species was originally named ''Buccinum granulatum'', and was described by the Austrian naturalist
Ignaz von Born Ignaz Edler von Born, also known as Ignatius von Born ( hu, Born Ignác, ro, Ignațiu von Born, cs, Ignác Born) (26 December 1742 in Alba Iulia, Grand Principality of Transylvania, Habsburg monarchy – 24 July 1791 in Vienna), was a mineral ...
in 1778. Born's description is in
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
and reads: :"''Testa ovata, transversim, obsolete sulcata, tessulis luteis seriatim maculata, labio granulato, cauda recurva''". Translated, this reads: :"Shell ovate, transversely obscurely sulcate r grooved regularly marked with yellow squares, the lip granulated, the tail recurved" Since 1778, this
taxon In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
has been recombined numerous times into different genera and
subgenera In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...
. Nearly a century after Born's description, in 1877, the
Swedish Swedish or ' may refer to: Anything from or related to Sweden, a country in Northern Europe. Or, specifically: * Swedish language, a North Germanic language spoken primarily in Sweden and Finland ** Swedish alphabet, the official alphabet used by ...
naturalist
Otto Andreas Lowson Mörch Otto Andreas Lowson Mörch (his last name also spelled Mørch) (17 May 1828 – 25 January 1878) was a biologist, specifically a malacologist. He lived in Sweden, in Denmark, and in France. Taxa described * Bibliography and taxa described by Ott ...
proposed a new combination and transferred this taxon to the genus ''Cassis'' and subgenus ''Semicassis''. In 1944, the American malacologist William James Clench recombined the species as ''Phalium (Semicassis) granulatum'', and five years later the Brazilian naturalist Frederico Lange de Morretes recombined it as ''Semicassis granulatum''. American malacologist Clifton S. Weaver reallocated it in the subgenus '' Tylocassis'' in 1962, though American malacologist
R. Tucker Abbott Robert Tucker Abbott (September 28, 1919 – November 3, 1995) was an American conchologist (seashells) and malacologist (molluscs). He was the author of more than 30 books on malacology, which have been translated into many languages. Abbot ...
recombined it as ''Phalium (Tylocassis) granulatum'' six years later. American malacologist Andrew C. Miller recombined it as ''Phalium granulatum'' in 1983, and German malacologist Kurt Kreipl recombined it as ''Semicassis (Semicassis) granulata'' in 1997. The currently accepted combination, ''Semicassis granulata'', was proposed by New Zealand paleontologist
Alan Beu Alan may refer to: People *Alan (surname), an English and Turkish surname *Alan (given name), an English given name **List of people with given name Alan ''Following are people commonly referred to solely by "Alan" or by a homonymous name.'' *Al ...
, based on
paleontological Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (geology), epoch (roughly 11,700 years before present). It includes t ...
data.


Subspecies

There is a similar-looking species, ''
Semicassis undulata ''Semicassis undulata'' is a Mediterranean species of medium-sized sea snail, a marine gastropod mollusc in the subfamily Cassinae, the helmet snails and bonnet snails. Taxonomy This taxon was previously sometimes referred to at subspecies ...
'', which lives 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
Macaronesian Islands Macaronesia (Portuguese: ''Macaronésia,'' Spanish: ''Macaronesia'') is a collection of four volcanic archipelagos in the North Atlantic, off the coasts of Africa and Europe. Each archipelago is made up of a number of Atlantic oceanic islands ...
, parts of the northeastern Atlantic. In 1791, that sea snail was given the specific name ''undulata'' by the German naturalist
Johann Friedrich Gmelin , fields = , workplaces = University of GöttingenUniversity of Tübingen , alma_mater = University of Tübingen , doctoral_advisor = Philipp Friedrich GmelinFerdinand Christoph Oetinger , academic_advisors = , doctora ...
. In 2015, this taxon was considered to be a subspecies of ''S. granulata'', and therefore was known as ''Semicassis granulata undulata''. ''Semicassis undulata'' has mistakenly been reported from the Western Atlantic Ocean, but does not occur there.Rosenberg, G. (2012). Semicassis granulata undulata (Gmelin, 1791). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=591482 on 2012-06-17


Forms

Some Scotch bonnets have a completely smooth and glossy shell. These were thought to be a different species, which was given the name ''cicatricosa'' by Gmelin in 1791. This taxon was recognized for a while, including up until 2010, as a separate species, ''Semicassis cicatricosa''. However, in 2015 this is considered to be only a
form Form is the shape, visual appearance, or configuration of an object. In a wider sense, the form is the way something happens. Form also refers to: *Form (document), a document (printed or electronic) with spaces in which to write or enter data ...
, therefore ''S. cicatricosa'' has become another synonym of ''S. granulata''. For this smooth and glossy form, the maximum recorded shell length is 60 mm.Welch, J.J. (2010). "The "Island Rule" and Deep-Sea Gastropods: Re-Examining the Evidence". '' PLoS ONE'' 5(1): e8776. . The minimum recorded depth for this form is 0 m; the maximum recorded depth is 6 m. In 1939, the shell form of ''Semicassis granulata'' which has nodules on the shoulder was named as a subspecies, ''Semicassis cicatricosa peristephes'', by American malacologists Henry G. Pilsbry and Thomas L. Mcginty. This supposed subspecies has since been considered a synonym of ''S. cicatricosa'', and consequently of ''S. granulata''.


Distribution

There are published records of the
nominate subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
''Semicassis granulata granulata'' from several warm-water and tropical areas of the Western
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 ...
. It is considered the most common species of ''
Cassinae The Cassidae are a taxonomic family of medium-sized, large, and sometimes very large sea snails commonly called helmet snails or bonnet snails. These are marine gastropod mollusks in the superfamily Tonnoidea and the clade Littorinimorpha.Go ...
'' in
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
. Regions and countries where this species occurs include the East Coast of the US, in
North Carolina North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and So ...
,
South Carolina )''Animis opibusque parati'' ( for, , Latin, Prepared in mind and resources, links=no) , anthem = " Carolina";" South Carolina On My Mind" , Former = Province of South Carolina , seat = Columbia , LargestCity = Charleston , LargestMetro = ...
,
Georgia Georgia most commonly refers to: * Georgia (country), a country in the Caucasus region of Eurasia * Georgia (U.S. state), a state in the Southeast United States Georgia may also refer to: Places Historical states and entities * Related to the ...
and
Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...
(East Florida, West Florida, and the Florida Keys). It has also been recorded on the Gulf Coast of the US, including
Louisiana Louisiana , group=pronunciation (French: ''La Louisiane'') is a state in the Deep South and South Central regions of the United States. It is the 20th-smallest by area and the 25th most populous of the 50 U.S. states. Louisiana is borde ...
and
Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...
. The species is known to occur in the
Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean Se ...
Coast of Central America, including Mexico ( Quintana Roo),
Nicaragua Nicaragua (; ), officially the Republic of Nicaragua (), is the largest country in Central America, bordered by Honduras to the north, the Caribbean to the east, Costa Rica to the south, and the Pacific Ocean to the west. Managua is the cou ...
,
Costa Rica Costa Rica (, ; ; literally "Rich Coast"), officially the Republic of Costa Rica ( es, República de Costa Rica), is a country in the Central American region of North America, bordered by Nicaragua to the north, the Caribbean Sea to the no ...
,
Panama Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Cos ...
and
Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...
, as well as
Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...
(
Gulf of Venezuela The Gulf of Venezuela is a gulf of the Caribbean Sea bounded by the Venezuelan states of Zulia and Falcón and by La Guajira Department, Colombia. The western side is formed by the Guajira Peninsula. A strait connects it with Maracaibo Lake to ...
,
Carabobo , anthem = '' Himno del Estado Carabobo'' , image_map = Carabobo in Venezuela.svg , map_alt = , map_caption = Location within Venezuela , pushpin_map = , pushpin_map_ ...
,
Sucre Sucre () is the Capital city, capital of Bolivia, the capital of the Chuquisaca Department and the List of cities in Bolivia, 6th most populated city in Bolivia. Located in the south-central part of the country, Sucre lies at an elevation of . T ...
, Isla Margarita and
Los Testigos Islands Los Testigos Islands ( es, Islas Los Testigos, Witnesses Islands) are a group of islands in the southeastern Caribbean Sea. They are a part of the ''Dependencias Federales'' (Federal Dependencies) of Venezuela. Geography The Los Testigos Islands ...
). It is also found in
Bermuda ) , anthem = "God Save the King" , song_type = National song , song = " Hail to Bermuda" , image_map = , map_caption = , image_map2 = , mapsize2 = , map_caption2 = , subdivision_type = Sovereign state , subdivision_name = , e ...
, the
Greater Antilles The Greater Antilles ( es, Grandes Antillas or Antillas Mayores; french: Grandes Antilles; ht, Gwo Zantiy; jam, Grieta hAntiliiz) is a grouping of the larger islands in the Caribbean Sea, including Cuba, Hispaniola, Puerto Rico, Jamaica, and ...
,
Cuba Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is an island country comprising the island of Cuba, as well as Isla de la Juventud and several minor archipelagos. Cuba is located where the northern Caribbea ...
,
Jamaica Jamaica (; ) is an island country situated in the Caribbean Sea. Spanning in area, it is the third-largest island of the Greater Antilles and the Caribbean (after Cuba and Hispaniola). Jamaica lies about south of Cuba, and west of His ...
and
Puerto Rico Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and Unincorporated ...
, and further south in the Atlantic coast of
South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
,
Suriname Suriname (; srn, Sranankondre or ), officially the Republic of Suriname ( nl, Republiek Suriname , srn, Ripolik fu Sranan), is a country on the northeastern Atlantic coast of South America. It is bordered by the Atlantic Ocean to the north ...
,
Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
(
Amapá Amapá () is one of the 26 states of Brazil. It is in the northern region of Brazil. It is the second least populous state and the eighteenth largest by area. Located in the far northern part of the country, Amapá is bordered clockwise by Fr ...
,
Maranhão Maranhão () is a state in Brazil. Located in the country's Northeast Region, it has a population of about 7 million and an area of . Clockwise from north, it borders on the Atlantic Ocean for 2,243 km and the states of Piauí, Tocantins and ...
,
Ceará Ceará (, pronounced locally as or ) is one of the 26 states of Brazil, located in the northeastern part of the country, on the Atlantic coast. It is the eighth-largest Brazilian State by population and the 17th by area. It is also one of the ...
,
Rio Grande do Norte Rio Grande do Norte (, , ) is one of the states of Brazil. It is located in the northeastern region of the country, forming the northeasternmost tip of the South American continent. The name literally translates as "Great Northern River", ref ...
,
Pernambuco Pernambuco () is a state of Brazil, located in the Northeast region of the country. With an estimated population of 9.6 million people as of 2020, making it seventh-most populous state of Brazil and with around 98,148 km², being the 19 ...
,
Alagoas Alagoas (, ) is one of the 27 federative units of Brazil and is situated in the eastern part of the Northeast Region. It borders: Pernambuco (N and NW); Sergipe (S); Bahia (SW); and the Atlantic Ocean (E). Its capital is the city of Maceió. It ...
,
Bahia Bahia ( , , ; meaning "bay") is one of the 26 Federative units of Brazil, states of Brazil, located in the Northeast Region, Brazil, Northeast Region of the country. It is the fourth-largest Brazilian state by population (after São Paulo (sta ...
, Espírito Santo,
Rio de Janeiro Rio de Janeiro ( , , ; literally 'River of January'), or simply Rio, is the capital of the state of the same name, Brazil's third-most populous state, and the second-most populous city in Brazil, after São Paulo. Listed by the GaWC as a b ...
,
São Paulo São Paulo (, ; Portuguese for 'Saint Paul') is the most populous city in Brazil, and is the capital of the state of São Paulo, the most populous and wealthiest Brazilian state, located in the country's Southeast Region. Listed by the GaWC a ...
, Paraná and Santa Catarina), and also in
Uruguay Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...
. As of 2009, this species had apparently not been reported in the literature as occurring in the
Lesser Antilles The Lesser Antilles ( es, link=no, Antillas Menores; french: link=no, Petites Antilles; pap, Antias Menor; nl, Kleine Antillen) are a group of islands in the Caribbean Sea. Most of them are part of a long, partially volcanic island arc betwe ...
. In contrast, the species ''
Semicassis undulata ''Semicassis undulata'' is a Mediterranean species of medium-sized sea snail, a marine gastropod mollusc in the subfamily Cassinae, the helmet snails and bonnet snails. Taxonomy This taxon was previously sometimes referred to at subspecies ...
'' occurs 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 parts of the North Atlantic Ocean, including
Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...
and the
Azores ) , motto =( en, "Rather die free than subjected in peace") , anthem= ( en, "Anthem of the Azores") , image_map=Locator_map_of_Azores_in_EU.svg , map_alt=Location of the Azores within the European Union , map_caption=Location of the Azores wi ...
.


Anatomy

;Shell description The egg-shaped shell of this species usually grows to 40–55 mm in length (1 1/2" - 2 1/8") (the maximum recorded shell length is 121 mm (4.76 in)).''Semicassis granulata'' (Born, 1778)
Malacolog Version 4.1.1. A Database of Western Atlantic Marine Mollusca. Accessed 14 December 2009.
It is thick and solid, with a moderately high spire and rounded
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 ...
, and adult specimens have approximately five whorls. The
protoconch A protoconch (meaning first or earliest or original shell) is an embryonic or larval shell which occurs in some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod. In older texts it is also called ...
is rounded, colored cream with an orange to brown apex. The
teleoconch The gastropod shell is part of the body of a gastropod or snail, a kind of mollusc. The shell is an exoskeleton, which protects from predators, mechanical damage, and dehydration, but also serves for muscle attachment and calcium storage. Some ...
is sculptured by spiral grooves crossed by mostly rather faint growth lines. Its surface varies in the degree of shell sculpture that is present. Some shells are completely smooth with a high gloss, whereas other shells are grooved. The surface of some shells is granulated, and some even have nodules on the shoulders of the whorls. Several times at different growth stages, the shell develops a thick outer lip, which is characteristic of the subfamily
Cassinae The Cassidae are a taxonomic family of medium-sized, large, and sometimes very large sea snails commonly called helmet snails or bonnet snails. These are marine gastropod mollusks in the superfamily Tonnoidea and the clade Littorinimorpha.Go ...
. The snail rests between each of these stages of growth, and usually absorbs the entire outer lip before it begins to grow again. In some cases, especially in deep water, the Scotch bonnet does not absorb the outer lip completely, leaving behind a
varix A varix (pl. varices) is an abnormally dilated vessel with a tortuous course. Varices usually occur in the venous system, but may also occur in arterial or lymphatic vessels. Examples of varices include: * Varicose veins, large tortuous veins usua ...
on the whorls of the mature shell. The shell has a large
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 ...
, with a thick outer lip, and a glossy, oval parietal shield. The outer lip has a series of short, strong lirae, giving it a toothed appearance. The lower part of the inner lip near the siphonal notch has many "pimple-like" bumps or pustules. It has a yellow to brown corneous operculum, with an outline that matches the aperture's contour. The shell is colored pale tan or creamy white, sometimes purplish, with regularly-arranged, orange to light brown rectangular markings that often appear faded, even in fresh specimens. Shells of adult females are larger than those of males.


Ecology

Scotch bonnets are
predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
s; they search for their food on sandy stretches of the ocean floor, where they consume
echinoderms An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea li ...
such as sand dollars, sea biscuits, and other
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 ...
s (such as ''
Echinocardium cordatum ''Echinocardium cordatum'', also known as the common heart urchin or the sea potato, is a sea urchin in the family (biology), family Loveniidae. It is found in sub-tidal regions in the NE Atlantic. Other un-named species have been identified as t ...
''), drilling into their
tests Test(s), testing, or TEST may refer to: * Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities Arts and entertainment * ''Test'' (2013 film), an American film * ''Test'' (2014 film), ...
with the aid of
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 ...
.


Habitat

''Semicassis granulata'' lives on sandy substrate in moderately shallow water, as well as rocky
tide pool A tide pool or rock pool is a shallow pool of seawater that forms on the rocky intertidal shore. Many of these pools exist as separate bodies of water only at low tide. Many tide pool habitats are home to especially adaptable animals that ...
s close to the shore. Off the coast of North Carolina, divers and local fisherman frequently find Scotch bonnets at depths of about ; however, live specimens can be found in depths from . Empty shells have been found in depths of up to . These snails are often found in association with the offshore Atlantic calico scallop beds, probably attracted by the abundant food. Shipwrecks also seem to provide a good habitat for this species.


Life cycle

During the spring, favorable food supplies, adequate light, and optimum water temperature provide conditions for breeding and early growth. At this time, the female deposits hundreds of egg capsules in tower-shaped structures about high. The male fertilizes these eggs. After fertilization, the eggs develop into trochophore larvae, and the eggs subsequently hatch as free swimming microscopic
veliger A veliger is the planktonic larva of many kinds of sea snails and freshwater snails, as well as most bivalve molluscs (clams) and tusk shells. Description The veliger is the characteristic larva of the gastropod, bivalve and scaphopod ...
larvae, which can be carried some distance on ocean currents. Growth is slow, and the veligers are carried by the ocean currents for up to 14 weeks. As the veligers mature, they develop their first shell (the smooth
protoconch A protoconch (meaning first or earliest or original shell) is an embryonic or larval shell which occurs in some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod. In older texts it is also called ...
) and turn into very small juvenile snails, at which point they sink to the ocean floor. As is the case in all shelled mollusks, the
mantle A mantle is a piece of clothing, a type of cloak. Several other meanings are derived from that. Mantle may refer to: *Mantle (clothing), a cloak-like garment worn mainly by women as fashionable outerwear **Mantle (vesture), an Eastern Orthodox ve ...
is what secretes the shell; shell growth begins at what will later become the apex of the shell, and typically rotates clockwise. As the animal gradually matures, the mantle continues to secrete shell material. Scotch bonnets complete maturation in one to six years. However, some have lived more than six years.


Predators

The Scotch bonnet is preyed upon by vertebrates, such as fish, and invertebrates, including crabs such as the
blue crab Blue crab may refer to: * Blue Crab 11, an American sailboat design * ''Callinectes sapidus'' – Chesapeake or Atlantic blue crab of the West Atlantic, introduced elsewhere * ''Cardisoma guanhumi'' – blue land crab of the West Atlantic * '' Disc ...
and the
Florida stone crab The Florida stone crab (''Menippe mercenaria'') is a crab found in the western North Atlantic, from Connecticut to Colombia, including Texas, the Gulf of Mexico, Belize, Mexico Jamaica, Cuba, The Bahamas, and the East Coast of the United States. ...
. Crabs can crush the snail's shell, eating the soft internal organs and muscle tissue. The snail's only defense mechanism against predation is to draw its body into the shell. By doing so, they can at least partially close the aperture using the operculum.


Use by other invertebrates

After death, the empty shell of this sea snail is often used by
hermit crab Hermit crabs are anomuran decapod crustaceans of the superfamily Paguroidea that have adapted to occupy empty scavenged mollusc shells to protect their fragile exoskeletons. There are over 800 species of hermit crab, most of which possess an a ...
s. On the coast of the
Caraguatatuba Caraguatatuba, widely known by its abbreviation ''Caraguá'', is a city in the eastern part of the southern state of São Paulo in Brazil. It is part of the Metropolitan Region of Vale do Paraíba e Litoral Norte. The population is 123,389 (2020 ...
,
Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
, a study of shell use in the diogenid hermit crab species '' Isocheles sawayai'' was carried out. This study revealed that 11.5% of the population of these hermit crabs were using shells of ''Semicassis granulata''. The occupation of shell type was reported as not being random, but was instead described as being influenced by the weight, size, shape and internal volume of the shell, the occurrence of epibionts such as bryozoans on the shell, and the degree of resistance the shell offered to predation and desiccation.


Human use

In 1965, the US state of North Carolina named the Scotch bonnet as its official state shell, in honor of the abundance of Scottish settlers that founded the state. With this designation, North Carolina became the first state in the US to have a state shell. Populations of ''S. granulata'' have been suffering a decline due to increased collection and accidental harvesting by commercial fishermen.


References


Further reading

* *


External links


Jacksonville shell club, shell images

''Phalium granulatum'' info at CLEMAN


- in Pleistocene * Abbott, American Seashells, 1954
pages 192-193
* {{Taxonbar, from=Q1972146 Cassidae Gastropods described in 1778 Taxa named by Ignaz von Born Symbols of North Carolina