Hide in Your Shell Trivia Quiz

Also known as St James shell, the king or great scallop (Pecten maximus) is one of the most readily recognizable mollusks, with its ribbed, fan-shaped shell and "ears" of equal size on each side of the apex. It belongs to the order Pectinida of the class Bivalvia, one of the seven living classes of mollusks, and the second-largest of the phylum. The names of the order, the family (Pectinidae) and the genus (Pecten) come from the Latin word for comb or rake.

The king scallop is native to the eastern North Atlantic Ocean, and has been found as far south as West Africa. Like most other bivalves, it is a filter feeder that eats plankton. It often settles in a small hollow on the sea floor covering its upper (left) valve with mud, sand, gravel and living organisms (as shown in the photo) to hide from predators. The lower (right) valve is considerably deeper, which allows the scallop to be less visible. Its powerful adductor muscle (which is the part of the animal that is eaten) rapidly opens and closes the shell when the animal is swimming.

Though the king scallop is highly prized as food, its importance extends to other aspects of human culture. A symbol of fertility since ancient times, it was one of the emblems of Aphrodite, the Greek goddess of love and beauty, and its Roman counterpart, Venus - hence the shell's appearance in Sandro Botticelli's celebrated painting of "The Birth of Venus". A scallop shell is also associated with the Way of St James, Europe's most famous pilgrimage route, and has been adopted as a logo by Shell, one of the world's largest oil and gas companies.

True oysters like the Pacific or Japanese oyster (Magallana gigas) belong to the family Ostreidae of the order Ostreida, which is part of the large mollusk class Bivalvia. As their common name implies, these animals are native to the Northwest Pacific Ocean, where they are found mainly in river estuaries. They have elongated shells, which can reach a length of 40 cm (16 in), with a rough, calcified upper surface. The two valves are slightly different in shape and size from each other, as the right valve is somewhat concave.

Oysters are largely sedentary, forming large beds on rocks or other hard marine surfaces that provide a favourable habitat to many small animal species, including other bivalves. They are filter feeders, able to filter large amounts of water to ingest nutrients. Unlike other bivalves, they often close the valves of their shells to enter a resting state.

Pacific oysters are the most widely farmed and commercially important oyster species: in Europe they have replaced the native (and smaller) European flat oyster (Ostrea edulis) as the most popular species of edible oyster. Oysters have been eaten by humans for thousands of years, and oyster farming has been practiced at least since the times of the Roman Empire. The oysters in the photo come from the Ile de Ré off the Atlantic coast of France, where one of the earliest oyster farms of the modern era was established in the 19th century.

The giant African land snail (Lissachatina fulica) belongs to the order Stylommatophora of the class Gastropoda, which includes most species of of air-breathing land snails and slugs. The name of the family Achatinidae comes from the Greek word for "agate" - a reference to these large tropical snails' distinctively patterned shells. All members of this family are native to sub-Saharan Africa; the giant African land snail in particular is native to East Africa, but has been introduced to most tropical regions of the world.

The African giant land snail is one of the largest of all land snails, easily reaching a length of over 20 cm (7.9 in); its conical, whorled shell is banded in various shades of brown. Though mainly herbivorous, this snail occasionally eats stones and bones as calcium sources, and may even indulge in cannibalism. These large gastropods are also known as hosts of a number of parasites, some of which can infect humans or domestic animals - which is bad news for those who like to keep these snails as pets.

In fact, the giant African land snail is an interesting case of a mollusk that has had both a positive and a negative role in human culture. In some parts of the US, in particular in Florida, it is regarded as an agricultural pest, and the pathogens they can transmit are cause for serious concern. Intestinal schistosomiasis, caused by the parasitic flatworm Schistosoma mansoni, is a debilitating tropical disease that infects over 200 million people every year. On the other hand, if properly cooked, the meat of these snails is edible, and is consumed particularly in China. Giant African land snails are also offered as sacrifices in Candomblé, one of the Afro-Brazilian syncretic religions.

One of the oldest living animal species, the chambered nautilus (Nautilus pompilio) is the best-known member of the family Nautilidae (order Nautilida) of the class Cephalopoda, and the type species of its genus. Its name comes from the Greek word for "sailor". Nautilids are the only living cephalopods that have an external shell: the other members of the family have no shell at all (as is the case of octopuses and squid), or they have an internalized one (as in cuttlefish). Nautilids also have cirri, thin tentacles without suckers but with adhesive capabilities, whose number is not set, but depends on sex and individual: it is not unusual to find specimens with over 90 cirri.

The chambered nautilus is found in the South Pacific, usually near coral reefs. A carnivorous species, it feeds on both carrion and living animals, mainly crustaceans and other molluscs. The largest subspecies of Nautilus pompilio is often referred to as emperor nautilus because of its size: its shell diameter can reach 25 cm (10 in). A nautilus shell is a true wonder of nature, often cited as an example of logarithmic spiral. The chambers within the shell are filled with gas, which helps to control buoyancy. While the outer layer of the shell is pale-coloured with dark orange stripes for camouflage, the inner layer is lined with intensely lustrous nacre - the material of which pearls are made.

Because of their striking proportions and nacre layer, chambered nautilus shells have long been sought after for the making of jewelry and other ornaments. This has led to overfishing, so that the international trade of nautilus shells has been restricted by CITES (Convention on International Trade of Endangered Species) since 2016. In the Renaissance and Baroque eras, nautilus shells were often mounted in elaborate gold or silver settings, or even carved and painted.

The blue or common mussel (Mytilus edulis) is a bivalve mollusk of the family Mytilidae (order Mytilida). Readily recognizable by its blue or purple, elongated triangular shell with rounded edges, it is native to the North Atlantic Ocean. A closely related species, Mytilus galloprovincialis, is native to the Mediterranean Sea, the Black Sea and Western Europe, while other species in the same genus are found in the temperate waters of the Pacific Ocean and the Southern Hemisphere.

Blue mussels are medium-sized mollusks that attach themselves to rocks by strong bundles of thread-like protein strands known as byssus. They also use these threads, secreted by glands located in the foot, to attach themselves to other mussels, forming beds that can grow to very large sizes. As filter feeders that feed mainly on plankton, blue mussels play a major role in removing bacteria and other harmful substances from river estuaries and coastal waters; they are also used to monitor marine pollution.

Harvested for food since ancient times, blue mussels are now among the most important marine species subject to aquaculture. Their bright orange adductor muscles are prized in the cuisines of many countries, and prepared in a variety of ways. However, they require some rather labour-intensive scrubbing, and it is not advisable to eat them raw. While some species of freshwater mussels are farmed for the production of cultured pearls, the pearls occasionally produced by blue mussels (or other bivalves for that matter) have no commercial value.

Members of the family Conidae (order Neogastropoda) of the class Gastropoda, cone snails owe their name to the distinctive shape of their stunningly patterned shells. They are also notorious for their venom, which can be deadly to humans - hence their nickname of "killer snails". However, the marbled cone (Conus marmoreus) - here depicted in its natural habitat - is not as dangerous as fish-eating species such as the geographer cone (Conus geographus), which has caused human fatalities. The marbled cone is a tropical species, found in parts of the Indian Ocean and in the western South Pacific Ocean; it is usually between 3 cm (1.2 in) and 15 cm (6 in) in length.

Like all cone snails, the marbled cone is carnivorous, feeding mostly on other molluscs. These marine animals have a specialized structure called a radula tooth, a mini-harpoon attached to the tip of the radula, a tongue-like structure they use for feeding. This hollow, venom-loaded tooth is fired like a dart to sting and paralyze the cone snail's prey. The venom contains many different toxins (known as conotoxins) that act with remarkable speed and precision. Cone snail venom has been used to create drugs to treat a wide range of medical conditions, and other possible employs are being researched.

With its characteristic reticulated pattern and triangular white spots, the shell of the marbled cone is highly prized by collectors. This species has the distinction of having been the first cone snail described by great Swedish naturalist Linnaeus in 1758. Over a century earlier, in 1650, the marbled cone had been the subject of a beautiful etching by Rembrandt, titled simply "De schelp" (The Shell), in which the shell is depicted in reverse.

The spiny dye-murex (Bolinus brandaris) is a sea snail in the family Muricidae (the rock snails) of the order Neogastropoda. It lives mainly in the shallow waters of the Mediterranean Sea, where fossil shells dating from the Pliocene (3.6 - 2.6 million years ago) have also been found. All the sea snails in this family are carnivorous, and prey on other molluscs or small crustaceans. This species is medium-sized, usually growing to about 9 cm (3.5 in). Its golden-brown shell has a long siphonal canal (which looks like the stem on a fruit or leaf); each of the rows of spines to which this mollusk owes its common name corresponds to the end of a growth stage.

Though the spiny dye-murex is also edible, it is best known for being the source the highly prized fabric dye produced by the mucous secretions of its hypobranchial gland - the finest shade of purple, known as Tyrian purple, an extremely expensive symbol of royalty, wealth and power. The species was farmed intensively in ancient times, as each animal could only secrete a very small quantity of dye, and the extraction process was very labour-intensive (not to mention foul-smelling).

Other sea snails of the family Muricidae were used to produce dyes - namely the banded dye-murex (Hexaplex trunculus), which produced an indigo or purple-blue dye, and the red-mouthed rock shell (Stramonita haemastoma), whose dye was dark red. In modern times, spiny dye-murexes and their relatives are harvested as food, and are quite popular especially in parts of Spain and Italy.

Pearl oysters are bivalve molluscs of the genus Pinctada, part of the family Pteriidae of the order Pteriida; in spite of their name, they are not closely related to edible oysters (family Ostreidae of the order Ostreida). These molluscs are found mainly in tropical seas, though some species also live in temperate waters such as those of the Mediterranean Sea. All the species of Pinctada are characterized by an inner shell made of a strong layer of nacre - a material consisting of both organic and inorganic compounds, noted for its iridescence, also known as mother-of-pearl. Pearls are formed when the oyster releases nacre to cover an irritant or parasite that enters the shell.

The silver-lip pearl oyster is one of two varieties of Pintada maxima - the other being the gold-lip: these common names stem from the colouration of the interior's outer edge. Native to the South Pacific, this species can grow to 30 cm (12 in) in diameter. Together with the black-lip pearl oyster (Pinctada margaritifera), silver- and gold-lip oysters produce a large proportion of the cultured pearls marketed today. The pearls produced by Pinctada maxima are known as South Sea pearls, and are white or light-coloured, while those produced by Pinctada margaritifera (Tahitian pearls) are generally grey or black. In contrast with the stunning inner shell, the outer shell of pearl oysters looks rather unprepossessing, as the photo shows.

Silver- and gold-lip oysters are farmed in Indonesia, the Philippines, and in the waters around Broome, in Western Australia. The ear-shaped adductor muscle of these oysters, called "pearl meat", is regarded as a delicacy both in Asia and Australia, and commands very high prices.

A word of Algonquian (Narrangansett) origin, quahog is one of the many names of the hard clam (Mercenaria mercenaria), a bivalve mollusk of the family Veneridae of the order Venerida. The members of this family, which also includes the clams found in the Mediterranean Sea - are also known as Venus clams. Quahogs are native to the Atlantic coast of North America, and are found as far south as Florida.

Like other venerids, quahogs have roughly oval shells whose valves are usually of the same size; these thick, grayish-brown shells are characterized by concentric ridges. However, unlike oysters or mussels, which attach themselves to rocks or other substrate, clams burrow down in the mud or sand with their powerful foot. Quahogs are about 7.5-12.5 cm (3-5 in) long; a closely related species, the southern quahog (Mercenaria campechiensis), is slightly larger and paler in colour.

In fish markets, quahogs are referred to by various specialist names according to their size, such as peanuts, littlenecks and cherrystones. The US state of Rhode Island produces about one-quarter of the country's annual catch; the quahog has been the state's official shellfish since 1987. Besides their uses as food - which include several regional varieties of clam chowder - quahogs were used historically by the Native American peoples of the Eastern Atlantic seaboard to make the wampum beads that were traded with furs - hence the generic name of "Mercenaria", which comes from the Latin word for "payment".

Also known as Burgundy snail or escargot, the Roman snail (Helix pomatia) is a gastropod of the family Helicidae of the order Stylommatophora, which includes most land snails and slugs. This species is native to the European continent (though it is also been introduced to the US and Canada), where it is found in a variety of habitats. Common throughout its native range, this snail is nevertheless protected by laws that regulate (and in some cases prohibit) the harvesting of wild populations. As is the case with many other animal species, habitat destruction is an ongoing concern.

The Roman snail has a globular shell with a large aperture, which can be 3-4.5 cm (1.2-1.8 in) high and 3-5 cm (1.2-2 in) wide; its colour ranges to creamy white (as in the specimen in the photo) to light brown, sometimes with darker brown bands. Like all its close relatives, this snail feeds on live plants (with a preference for the common nettle, Urtica dioica) or dead plant matter. It is mainly nocturnal, and spends a large part of the year in hibernation or aestivation. This species can also be relatively long-lived, with a lifespan that can exceed 20 years in particular circumstances.

Helix pomatia's common name of Roman snail is due to its popularity in Ancient Rome, where these snails were eaten regularly, and occasionally bred in garden enclosures. The practice of collecting snails for food, however, dates back at least from the Stone Age. Roman snails are also popular in France (hence the Burgundy connection), where they are prepared with garlic butter and herbs. Before they are fit for human consumption, snails need to be thoroughly purged and cleaned - a process that can take several days.