I am the Mollusc Trivia Quiz

Answer:

Mollusca is a phylum of invertebrates (animals with no vertebral column) which includes a diverse array of members, both in structure and in habitat. There are a number of extinct species which are poorly known, but modern molluscs share three features, although some display them more prominently than others. These are a soft muscular body, a mantle (body wall that covers the muscle, leaving an interior body cavity between viscera and wall, and, in some species, forms into a shell), and some nervous system, in at least a primitive form. Except for bivalves (those with hard shells in two sections joined by a hinge), they also have a radula, a tongue-like structure made of chitin and covered in tooth-like structures called denticles which is used for cutting and ingesting food. Their bodies are bilaterally symmetrical.

Molluscs are divided into a number of classes, three of which have been represented in this quiz: Gastropoda, Bivalvia and Cephalopodia. Not included are Aplacophora (worm-like molluscs with no shell found in deep marine areas), Polyplacophora (marine mollusc with an external shell commonly called chiton), Monoplacophora (poorly defined class of deep sea molluscs with a single cap-like shell) and Scaphopoda (marine molluscs with a shell resembling an elephants tusk, leading to the common name of tusk shell). The members of these classes are generally less familiar - and some of them are still being debated by taxonomists.

Gastropods are generally called snails or slugs, and were at one time referred to as univalves, in contrast to the bivalves, because they have one shell. In a snail, this shell is large enough for the animal to withdraw its entire body inside the shell. Slugs have a shell which is either internal or so small that no withdrawal is possible. Semislugs, for what it is worth, are a group that have a shell of intermediate size: they can withdraw into it partially, but not completely. Snails and slugs are found on land and in the water, both fresh and marine.

The Giant African land snail (Lissachatina fulica) has a classic coiled shell which sits on top of the muscular foot as it moves around. It has proved to be a highly successful competitor outside its natural environment, and is considered an invasive species in many places. The banana slug is a genus (Ariolimax) of land slugs found in North America, not a single species. They are often bright yellow, as suggested by their common name. The greenlip abalone (Haliotis laevigata) is a marine snail found in the waters south of Australia whose shell is highly nacreous (resembling mother-of-pearl), and whose flesh is considered a delicacy.

Limpets are aquatic snails with a conical, rather than helical, shell. The term is commonly used to describe members of a number of different species based simply on this appearance. Taxonomists consider members of the subclass Patellogastropoda (which has numerous super families, families, genera and species) to be true limpets. They are usually found clinging to rocks or other firm surfaces.

Bivalves are marine and freshwater molluscs with their body enclosed in a two-part shell, hinged so it can open and close. Each half is called a valve, hence the name of this class. They have no head, and are mostly filter feeders. The oyster is one of the most familiar, with two totally different species called pearl oysters responsible for the production of natural pearls. Many bivalves are valued as a source of food. Bivalve shells come in a range of sizes, from Condylonucla maya (0.52 mm or 002 inches) to Kuphus polythalamia (1.52 m or 60.3 inches); the largest bivalve by mass is generally considered to be Tridacna gigas, a giant clam that can grow to over 200 kg or 440 pounds, despite its shell being only around 1.2 metres (47 inches).

The name razor clam may refer to a number of different species, in the same family but different genera, which share the appearance of an elongated shell, hinged along one of the long edges. They include the Pacific razor clam (Siliqua patula), the Atlantic razor clam (Siliqua costata), the Atlantic jackknife clam (Ensis leei) and the razor shell clam (Ensis magnus). All of them are popular foodstuffs in North America, where they can be found burrowing into the sand on the coast.
The blue mussel (Mytilus edulis), also known as the common mussel, is found in coastal waters around the world. the shell is roughly triangular, hinged along the shortest of the three sides. Mussels are semi-sessile. meaning they like to attach themselves to a surface, but can detach and move around to a new site when it is desired.

The Atlantic sea scallop (Placopecten magellanicus) is also called the giant sea scallop or just plain sea scallop. It is commercially important as a food, as is the case for many other members of its family, the Pectinidae. They are free swimming, propelling themselves by opening and closing their smooth round shells. The adductor muscle which controls this produces a firm white flesh; the bright orange roe (called coral in the food industry) is sometimes removed before the cooked scallop is served.

The name of the Pacific geoduck (Panopea generosa) comes from its name in an indigenous language of the Puget Sound region, gweduc, and is pronounced gooey-duck. Don't ask me why it is spelled the way it is. The geoduck is a large clam, with an elongated siphon that can extend up to a metre (3 feet) from the shell, itself an impressive 15-20 cm (6-8 inches) in length. It is the world's largest burrowing clam, and also one of the world's longest-lived animals, when it survives without being harvested for food, averaging around 150 years as determined by counting the rings in the shell.

Cephalopods, whose name means head-feet, are marine molluscs with a prominent head and arms and/or tentacles instead of the solid muscle found in gastropods and bivalves. They are sometimes called inkfish, as they have the ability to squirt ink as a defensive mechanism. They are found all over the world, and it is likely that the ocean depths contain many as-yet-unidentified species. Those that live near the coast are often considered a culinary delicacy - despite the fact that they are also widely recognised as one of the most intelligent invertebrates. Remember Paul the Octopus (26 January 2008 - 26 October 2010) who was supposed to have the psychic ability to predict the result of international football matches? What about Inky, who escaped from a New Zealand aquarium through a gap at the top of the tank then slithered across the floor to a waterpipe and was on his way to freedom in the Pacific!

Paul and Inky may be fun to contemplate, but not so the blue-ringed octopus, any of four species (maybe more, if taxonomists agree about some unclear species) in the genus Hapalochlaena which are extremely venomous. They live in tidal pools and coral reefs, and are small enough (15-20 cm or 5-8 inches) to be inconspicuous until the octopus is upset: within seconds the colour becomes bright yellow, with bright blue rings that flash on and off. Their bite is often painless, because the beak is small, but the neurotoxin it delivers can be fatal within minutes if not well treated. Despite this fearsome reputation, there have not been that many confirmed deaths recorded - around ten. Still, swimmers in the tropical waters of the Indian and Pacific Oceans do well to be wary.

The giant squid (Architeuthis dux), dwelling in the depths of the world's oceans, is often given as an example of abyssal gigantism - the tendency for animals that inhabit the deeper parts of the oceans to be larger than their relatives that live in the shallower regions near the coasts. They have eight arms and two tentacles, all lined with suction cups lined with chitin which it uses to capture its prey. Females tend to be larger than males (12-13 m versus 10 m) when measured from the tip of the posterior fins to the end of the two tentacles. This makes them longer than the colossal squid, but they are lighter because their mantle, which comprises most of their mass, is smaller than that of the colossal squid. The giant squid's tentacles are the longest of any cephalopod.

The incorrect answers are all crustaceans, arthropods with an external skeleton and two-jointed limbs. Names around the world are not consistent - the exact species designated by crayfish, for example, varies widely.