PeriostracumThe periostracum ( ) is a thin, organic coating (or "skin") that is the outermost layer of the shell of many shelled animals, including molluscs and brachiopods. Among molluscs, it is primarily seen in snails and clams, i.e. in gastropods and bivalves, but it is also found in cephalopods such as Allonautilus scrobiculatus. The periostracum is an integral part of the shell, and it forms as the shell forms, along with the other shell layers.
Aperture (mollusc)The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where the head-foot part of the body of the animal emerges for locomotion, feeding, etc. The term aperture is used for the main opening in gastropod shells, scaphopod shells, and also for Nautilus and ammonite shells. The word is not used to describe bivalve shells, where a natural opening between the two shell valves in the closed position is usually called a gape.
GastropodGastropods (; previously known as Univalves; class Gastropoda) are a vast and diverse group of invertebrates within the phylum Mollusca, comprising the animals commonly known as snails and slugs. With an estimated 65,000 to 80,000 living species, they form the second-largest animal class after the insects. The fossil record of gastropods extends back to the Late Cambrian.
TurritellaTurritella is a genus of medium-sized sea snails with an operculum, marinegastropodmollusks in the family Turritellidae. They have tightly coiled shells, whose overall shape is basically that of an elongated cone. The name Turritella comes from the Latin word turritus 'turreted, towered' and the diminutive suffix -ella. SpeciesValidValid species within the genus Turritella are listed below. Fossil species are marked with a dagger "†".
Operculum (gastropod)An operculum (Latin for 'cover, covering'; pl. opercula or operculums) is a corneous or calcareous anatomical structure like a trapdoor that exists in many (but not all) groups of sea snails and freshwater snails, and also in a few groups of land snails, including the Helicinidae, Cyclophoridae, Aciculidae, Maizaniidae and Pomatiidae.
Mollusc shellThe mollusc (or mollusk) shell is typically a calcareous exoskeleton which encloses, supports and protects the soft parts of an animal in the phylum Mollusca, which includes snails, clams, tusk shells, and several other classes. Not all shelled molluscs live in the sea; many live on the land and in freshwater.
Semi-slugSemi-slugs, also spelled semislugs, are land gastropods whose shells are too small for them to retract into, but not quite vestigial. The shell of some semi-slugs may not be easily visible on casual inspection, because the shell may be covered over with the mantle. This is a type of gastropod that is intermediate between a slug (without an external shell) and a land snail (with a large enough shell to retract completely into).
MalacologyMalacology, from Ancient Greek μαλακός (malakós), meaning "soft", and λόγος (lógos), meaning "study", is the branch of invertebrate zoology that deals with the study of the Mollusca (molluscs or mollusks), the second-largest phylum of animals in terms of described species after the arthropods. Mollusks include snails and slugs, clams, and cephalopods, along with numerous other kinds, many of which have shells.
SlugSlug or land slug is a common name for any apparently shell-less terrestrialgastropodmollusc. The word slug is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a small internal shell, particularly sea slugs and semi-slugs (this is in contrast to the common name snail, which applies to gastropods that have a coiled shell large enough that they can fully retract their soft parts into it).
ConchologyConchology (from Ancient Greek κόγχος (kónkhos) 'cockle' and -λογία (-logía) 'study of') is the study of mollusc shells. Conchology is one aspect of malacology, the study of molluscs; however, malacology is the study of molluscs as whole organisms, whereas conchology is confined to the study of their shells. It includes the study of terrestrial and freshwater mollusc shells, as well as seashells and extends to the study of a gastropod's operculum.
ExoskeletonAn exoskeleton (from Ancient Greek (éxō)'outer' and (skeletós)'skeleton') is a skeleton that is on the exterior of an animal in the form of hardened integument, which both supports the body's shape and protects the internal organs, in contrast to an internal endoskeleton (e.g. that of a human) which is enclosed underneath other soft tissues. Some large, hard and non-flexible protective exoskeletons are known as shell or armour.
MolluscaMollusca is a phylum of protostomicinvertebrateanimals, whose members are known as molluscs or mollusks (). 86,600 extantspecies of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The number of additional fossil species is estimated between 60,000 and 100,000, and the proportion of undescribed extant species is very high. Many taxa remain poorly studied.*As an Amazon Associate I earn from qualifying purchases.