''Spondylus'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

s, the only genus in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Spondylidae and subfamily Spondylinae. They are known in English as spiny oysters or thorny oysters (although they are not, in fact, true oysters, but are related to

scallop Scallop () is a common name that encompasses various species of marine bivalve molluscs in the taxonomic family Pectinidae, the scallops. However, the common name "scallop" is also sometimes applied to species in other closely related famili ...

s).

Description

The many species of ''Spondylus'' vary considerably in appearance. They are grouped in the same superfamily as the

s. They are not closely related to true oysters (family

Ostreidae The Ostreidae, the true oysters, include most species of molluscs commonly consumed as oysters. Pearl oysters are not true oysters, and belong to the order Pteriida. Like scallops, true oysters have a central adductor muscle, which means the s ...

); however, they do share some habits such as cementing themselves to rocks rather than attaching themselves by a

byssus A byssus () is a bundle of filaments secreted by many species of bivalve mollusc that function to attach the mollusc to a solid surface. Species from several families of clams have a byssus, including pen shells ( Pinnidae), true mussels (Mytili ...

. The two halves of their shells are joined with a ball-and-socket type of hinge, rather than with a toothed hinge as is more common in other bivalves. They also still retain vestigial anterior and posterior ''auricles'' ("ears", triangular shell flaps) along the hinge line, a characteristic feature of scallops, although not of oysters. As is the case in all scallops, ''Spondylus'' spp. have multiple eyes around the edges of their mantle, and they have relatively well-developed

nervous system In biology, the nervous system is the complex system, highly complex part of an animal that coordinates its behavior, actions and sense, sensory information by transmitting action potential, signals to and from different parts of its body. Th ...

s. Their nervous

ganglia A ganglion (: ganglia) is a group of neuron cell bodies in the peripheral nervous system. In the somatic nervous system, this includes dorsal root ganglia and trigeminal ganglia among a few others. In the autonomic nervous system, there a ...

are concentrated in the

viscera In a multicellular organism, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to a ...

l region, with recognisable optic lobes connected to the eyes.

Evolutionary history

The genus ''Spondylus'' appeared in the Mesozoic era, and is known in the fossil records from the

Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...

Cassian beds in Italy (235 to 232 million years ago) onward. Approximately 40 extinct species are known. Spondylidae - Spondylus crassicosta

Fossils of these molluscs may be found in fossiliferous marine strata all over the world. For example, they are present in

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

rocks in the Fort Worth Formation of

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

, and in the Trent River Formation of

Vancouver Island Vancouver Island is an island in the northeastern Pacific Ocean and part of the Canadian province of British Columbia. The island is in length, in width at its widest point, and in total area, while are of land. The island is the largest ...

, as well as in other parts of North America.Finsley, Chalres. 1999. A Field Guide to the Fossils of Texas. Gulf Publishing. Lanham, Maryland. plate 55.Ludvigsen, Rolf & Beard, Graham. 1997. West Coast Fossils: A Guide to the Ancient Life of Vancouver Island. pg. 104

Distribution

Spiny oysters are found in all subtropical and (especially) tropical seas, usually close to the coasts.

Ecology

''Spondylus'' are

filter feeder Filter feeders are aquatic animals that acquire nutrients by feeding on organic matters, food particles or smaller organisms (bacteria, microalgae and zooplanktons) suspended in water, typically by having the water pass over or through a s ...

s. The adults live cemented to hard substrates, a characteristic they share, by convergent evolution, with true oysters and jewel boxes. Like the latter, they are protected by spines and a layer of epibionts and, like the former, they can produce

pearl A pearl is a hard, glistening object produced within the soft tissue (specifically the mantle (mollusc), mantle) of a living Exoskeleton, shelled mollusk or another animal, such as fossil conulariids. Just like the shell of a mollusk, a pear ...

s. The type of substrate they use depends on the species: many only attach to coral, and the largest diversity of species is found in tropical coral reefs; others (particularly '' S. spinosus''), however, easily adapt to manufactured structures such as boats, pipes, and docks thereby becoming significant

invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...

. Often other species are found attached to the shells of other species, perhaps the most common being found attached to the genus ''Malleus''.

Uses

Archaeological Archaeology or archeology is the study of human activity through the recovery and analysis of material culture. The archaeological record consists of Artifact (archaeology), artifacts, architecture, biofact (archaeology), biofacts or ecofacts, ...

evidence indicates that people in

Neolithic The Neolithic or New Stone Age (from Ancient Greek, Greek 'new' and 'stone') is an archaeological period, the final division of the Stone Age in Mesopotamia, Asia, Europe and Africa (c. 10,000 BCE to c. 2,000 BCE). It saw the Neolithic Revo ...

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

were trading the shells of ''S. gaederopus'' to make bangles and other ornaments throughout much of the Neolithic period. The main period of Neolithic use appears to have been from around 5350 to 4200 BC. The shells were harvested from the

Aegean Sea The Aegean Sea is an elongated embayment of the Mediterranean Sea between Europe and Asia. It is located between the Balkans and Anatolia, and covers an area of some . In the north, the Aegean is connected to the Marmara Sea, which in turn con ...

, but were transported far into the center of the continent. In the LBK and Lengyel cultures, ''Spondylus'' shells from the Aegean Sea were worked into bracelets and belt buckles. Over time styles changed with the middle Neolithic favouring generally larger barrel-shaped beads and the late Neolithic smaller favoring flatter and disk-shaped beads. Significant finds of jewelry made from ''Spondylus'' shells were made at the

Varna Necropolis The Varna Necropolis (), or Varna Cemetery, is a burial site in the western industrial zone of Varna, Bulgaria, Varna (approximately half a kilometre from Lake Varna and 4 km from the city centre), internationally considered one of the key a ...

. During the late Neolithic the use of ''Spondylus'' in grave goods appears to have been limited to women and children. ''S. crassisquama'' is found off the coast of

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

and

Ecuador Ecuador, officially the Republic of Ecuador, is a country in northwestern South America, bordered by Colombia on the north, Peru on the east and south, and the Pacific Ocean on the west. It also includes the Galápagos Province which contain ...

and has been important to

Andean The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long and wide (widest between 18°S ...

peoples since

pre-Columbian In the history of the Americas, the pre-Columbian era, also known as the pre-contact era, or as the pre-Cabraline era specifically in Brazil, spans from the initial peopling of the Americas in the Upper Paleolithic to the onset of European col ...

times, serving as both an offering to the fertility goddess Pachamama and as currency. In fact, much like in Europe, the trade in ''Spondylus'' shells also reached far and wide, as pre-Hispanic Ecuadorian peoples traded them with peoples as far north as present-day

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

and as far south as the central

Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...

. The Moche people of ancient

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

regarded the sea and animals as sacred; they used ''Spondylus'' shells in their art and depicted ''Spondylus'' in effigy pots. Spondylus also were harvested from the

Gulf of California The Gulf of California (), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Vermejo''), is a marginal sea of the Pacific Ocean that separates the Baja California peninsula from ...

and traded to tribes throughout Mexico and the American Southwest. ''Spondylus'' shells were the driving factor of trade within the Central Andes and were used in a similar manner to gold nuggets, copper hatches, coca, salt, red pepper, and cotton cloth. The use of ''Spondylus'' shells is what led to an economy of sorts in the Central Andes and led to the development of a merchant class, "mercardes", in different cultures within the Central Andes. This caused the development of different styles of trade that went through evolutionary changes throughout pre-Columbian times. These are reciprocity (home based), reciprocity (boundary), down-the-line trade, central place redistribution, central place market exchange, emissary trading, and port of trade. These modes of trade dictate the way that the ''Spondylus'' shells are traded, as well as who is benefiting the most from the trades. Modes such as central place redistribution require the entity that is the central place to be the one that gains the most benefit from the trade, and modes such as emissary trading and port of trade are the modes that started the "mercardes" class within the Central Andes. The value of ''Spondylus'' shells in the Central Andes stems from supply and demand. There was a great demand for ''Spondylus'' shells due to the "fetishistic needs to the south". Even today, there are collectors of ''Spondylus'' shells, and a commercial market exists for them. Additionally, some species (especially ''S. americanus'') sometimes are found in the saltwater aquariums. ''S. limbatus'' was commonly ground for mortar in Central America, giving raise to its junior synonym, "''S. calcifer"''. ''Spondylus'' is fished primarily for its adductor muscle, or "callus", which is a high-value foodstuff. Some Mediterranean species are edible and are commonly consumed, with ''S. gaederopus'' in particular being popular in

Sardinia Sardinia ( ; ; ) is the Mediterranean islands#By area, second-largest island in the Mediterranean Sea, after Sicily, and one of the Regions of Italy, twenty regions of Italy. It is located west of the Italian Peninsula, north of Tunisia an ...

. Tropical species, however, tend to bioaccumulate saxitoxin. The Romans ate Spondylus species. Macrobius in Saturnalia III.13 describes a dinner party in 63 BCE in which there were two courses of ''Spondylus''.

Aztec culture

In addition to its significance in the

times, ''Spondylus crassiquama'' was also an important part of

Aztec The Aztecs ( ) were a Mesoamerican civilization that flourished in central Mexico in the Post-Classic stage, post-classic period from 1300 to 1521. The Aztec people included different Indigenous peoples of Mexico, ethnic groups of central ...

culture.

''Spondylus'' held immense religious value amongst

culture

pre-columbian In the history of the Americas, the pre-Columbian era, also known as the pre-contact era, or as the pre-Cabraline era specifically in Brazil, spans from the initial peopling of the Americas in the Upper Paleolithic to the onset of European col ...

times and is also a great representation of the relationship between the Aztec empire and nature. To Aztec groups and peoples, ''Spondylus'' was a gift from the deities to be celebrated. Certain ''Spondylus'' groups were formed as a result of when and where they may be found seasonally and tend to connect a particular group of ''Spondylus'' to specific religious symbols such as the Fertility goddess, the Moon goddess, the Sun god, and the mountain spirits. This led to certain groups of ''Spondylus'' being associated with seasonal weather events such as heavy rains or increases in sea temperature along the coast, as those events were closely associated with particular deities or spirits in

culture.

''Spondylus'' had several key uses in

Aztec history, most predominantly its importance in jewelry, art, and sculpture. Another use of ''Spondylus'', that had to be executed with extreme detail and precision, was to create breathtaking masks, vests, and other items individuals would use to express how important or wealthy they were in life and death. Having the most beautiful ''Spondylus'' pieces, meant that individual had immense power within the community.

Species

Spondylidae taxonomy has undergone many revisions, mostly due to the fact that identification is traditionally based on the shell alone, and this is highly variable. To add to this, while some shallow-water species are extremely common, at least two deep-water species are known from a single specimen, while a third (''S. gravis'') was only identified in the late 1900s. At least another common species (''S. regius'') has a different shell when it grows in deep water. WLA hmns Spondylus linguaefelis 2

*'' Spondylus americanus'' Hermann, 1781 – Atlantic thorny oyster *'' Spondylus anacanthus'' Mawe, 1823 – nude thorny oyster *'' Spondylus aonis'' d'Orbigny, 1850 *'' Spondylus asiaticus'' Chenu, 1844 *'' Spondylus asperrimus'' G. B. Sowerby II, 1847 *'' Spondylus aucklandicus'' P. Marshall, 1918 *'' Spondylus avramsingeri'' Kovalis, 2010 * † '' Spondylus bostrychites'' Guppy, 1867 *'' Spondylus butleri'' Reeve, 1856 *'' Spondylus candidus''

Lamarck Jean-Baptiste Pierre Antoine de Monet, chevalier de Lamarck (1 August 1744 – 18 December 1829), often known simply as Lamarck (; ), was a French naturalist, biologist, academic, and soldier. He was an early proponent of the idea that biolo ...

, 1819 *'' Spondylus clarksoni'' Lamprell, 1992 *'' Spondylus concavus'' Deshayes in Maillard, 1863 *'' Spondylus crassisquama''

, 1819 *'' Spondylus croceus'' Schreibers, 1793 *'' Spondylus darwini'' Jousseaume, 1882 *'' Spondylus deforgesi'' Lamprell & Healy, 2001 *'' Spondylus depressus'' Fulton, 1915 *'' Spondylus eastae'' Lamprell, 1992 *'' Spondylus echinatus'' Schreibers, 1793 *'' Spondylus erectospinosus'' Habe, 1973 *'' Spondylus exiguus'' Lamprell & Healy, 2001 *'' Spondylus exilis'' G. B. Sowerby III, 1895 *'' Spondylus fauroti'' Jousseaume, 1888 *'' Spondylus foliaceus'' Schreibers, 1793 *'' Spondylus gaederopus''

Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

, 1758 – European thorny oyster *'' Spondylus gloriandus'' Melvill & Standen, 1907 *'' Spondylus gloriosus'' Dall, Bartsch & Rehder, 1938 * † '' Spondylus granulosus'' Deshayes, 1830 *'' Spondylus gravis'' Fulton, 1915 *'' Spondylus groschi'' Lamprell & Kilburn, 1995 *'' Spondylus guadalupae'' Roemer, 1849Roemer, F. (1849). Texas : mit besonderer Rücksicht auf deutsche Auswanderung und die physischen Verhältnisse des Landes nach eigener Beobachtung. A. Marcus *'' Spondylus gussonii'' O. G. Costa, 1830 *'' Spondylus heidkeae'' Lamprell & Healy, 2001 *'' Spondylus imperialis'' Chenu, 1844 * '' Spondylus jamarci'' Okutani, 1983 *'' Spondylus Lamarckii'' Chenu, 1845 *'' Spondylus layardi'' Reeve, 1856 *'' Spondylus leucacanthus'' Broderip, 1833 *'' Spondylus limbatus'' G. B. Sowerby II, 1847 *'' Spondylus linguafelis'' G. B. Sowerby II, 1847 *'' Spondylus maestratii'' Lamprell & Healy, 2001 *'' Spondylus marinensis'' Cossignani & Allary, 2018 *'' Spondylus mimus'' Dall, Bartsch & Rehder, 1938 *'' Spondylus morrisoni'' Damarco, 2015 *'' Spondylus multimuricatus'' Reeve, 1856 *'' Spondylus multisetosus'' Reeve, 1856 * † '' Spondylus multistriatus'' Deshayes, 1830 *'' Spondylus nicobaricus'' Schreibers, 1793 *'' Spondylus occidens'' G. B. Sowerby III, 1903 *'' Spondylus ocellatus'' Reeve, 1856 *'' Spondylus orstomi'' Lamprell & Healy, 2001 *'' Spondylus ostreoides'' E. A. Smith, 1885 *'' Spondylus pratii'' Parth, 1990 *'' Spondylus proneri'' Lamprell & Healy, 2001 * '' Spondylus pseudogaederopus'' T. Cossignani, 2022 * '' Spondylus purpurascens'' T. Cossignani, 2022 * † '' Spondylus radula'' Lamarck, 1806 *'' Spondylus raoulensis'' W. R. B. Oliver, 1915 * † '' Spondylus rarispina'' Deshayes, 1830 *'' Spondylus reesianus'' G. B. Sowerby III, 1903 *'' Spondylus regius''

, 1758 – regal thorny oyster *'' Spondylus rippingalei'' Lamprell & Healy, 2001 *'' Spondylus rubicundus'' Reeve, 1856 *'' Spondylus senegalensis'' Schreibers, 1793 *'' Spondylus sinensis'' Schreibers, 1793 *'' Spondylus spinosus'' Schreibers, 1793 *'' Spondylus squamosus'' Schreibers, 1793 *'' Spondylus tenellus'' Reeve, 1856 *'' Spondylus tenuis'' Schreibers, 1793 *'' Spondylus tenuispinosus'' G. B. Sowerby II, 1847 *'' Spondylus tenuitas'' Garrard, 1966 *'' Spondylus variegatus'' Schreibers, 1793 *'' Spondylus varius'' G. B. Sowerby I, 1827 * † '' Spondylus vaudini'' Deshayes, 1858 *'' Spondylus versicolor'' Schreibers, 1793 *'' Spondylus victoriae'' G. B. Sowerby II, 1860 *'' Spondylus violacescens''

, 1819 *'' Spondylus virgineus'' Reeve, 1856 *'' Spondylus visayensis'' Poppe & Tagaro, 2010 *'' Spondylus zonalis''

, 1819 *'' Spondylus echinus'' Jousseaume in Lamy, 1927 ( taxon inquirendum) *'' Spondylus imbricatus'' Perry, 1811 (

nomen dubium In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium,'' it may be impossible to determine whether a ...

) *'' Spondylus microlepos''

, 1819 (

) *'' Spondylus unicolor'' G. B. Sowerby II, 1847 (

) See also: Tikod amo, an undescribed species

References

External links

Spondylidae
examples of the shells of most extant species

Session Abstracts
on ''Spondylus'' research at the 13th Meeting of the European Association of Archaeologists at Zadar, Croatia, September 2007

from the website of the Gladys Archerd Shell Collection at Washington State University Tri-Cities Natural History Museum
Article on "notched" ''Spondylus''
Neolithic artifacts in Europe

Bibliography

A full and constantly updated bibliography
on ''Spondylus'' spp. in Aegean, Balkan, European and American contexts * Lamprell, Kevin L.: ''Spondylus: Spiny Oyster Shells of the World'', E. J. Brill, Leiden, 1987 {{Authority control Spondylidae Bivalve genera Extant Triassic first appearances