Corneous is a biological and
medical term
Medical terminology is a language used to precisely describe the human body including all its components, processes, conditions affecting it, and procedures performed upon it. Medical terminology is used in the field of medicine
Medical terminolog ...
meaning horny, in other words made out of a substance similar to that of
horns and
hooves
The hoof (plural: hooves) is the tip of a toe of an ungulate mammal, which is covered and strengthened with a thick and horny keratin covering. Artiodactyls are even-toed ungulates, species whose feet have an even number of digits, yet the rum ...
in some
mammal
Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fu ...
s.
The word is generally used to describe natural or pathological anatomical structures made out of a hard layer of
protein. In mammals this protein would usually be
keratin
Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up scales, hair, nails, feathers, hor ...
.
The word corneous is also often used to describe the
operculum of a
snail
A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Ga ...
, a
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. ...
mollusc
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 est ...
. Not all gastropods have opercula, but in the great majority of those that do have one, the operculum is corneous. (However in several genera within a few families including the marine
Naticidae
Naticidae, common name moon snails or necklace shells, is a family of medium to large-sized predatory sea snails, marine gastropod molluscs in the clade Littorinimorpha. The shells of the species in this family are mostly globular in shape. ...
and the terrestrial
Pomatiidae, the operculum is primarily
calcareous
Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.
In zoology
''Calcareous'' is used as an adj ...
, in other words mostly made of
calcium carbonate.) Corneous opercula are made out of the protein
conchiolin
Conchiolins (sometimes referred to as conchins) are complex proteins which are secreted by a mollusc's outer epithelium (the mantle).
These proteins are part of a matrix of organic macromolecules, mainly proteins and polysaccharides, that ass ...
.
References
Corneousat
dictionary.com
Dictionary.com is an online dictionary whose domain was first registered on May 14, 1995. The primary content on Dictionary.com is a proprietary dictionary based on ''Random House Unabridged Dictionary'', with editors for the site providing new a ...
Animal anatomy
Mammal anatomy
Keratins
Biology terminology
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