Microscopy of keratin filaments inside cells.

Keratins are a family of fibrous proteins. Keratin is what makes up hair in animals, as well as horns, nails, hooves, shells, beaks, and feathers. The name comes from Greek word keras meaning "horn".

Keratins are tough and insoluble. They form the hard but non-mineral structures in reptiles, birds, amphibians and mammals. A similar biological toughness is found in chitin.

Variety of animal uses

Keratins are the main constituent of structures that grow from the skin:

Arthropods such as crustaceans often have parts of their exoskeleton made of keratin, sometimes in combination with chitin.

Keratins are also found in the gastrointestinal tracts of many animals, including roundworms (who also have an outer layer made of keratin).

Although it is now difficult to be certain, the scales, claws, some protective armour and the beaks of dinosaurs would, almost certainly, have been composed of a type of keratin.

Other Languages
አማርኛ: ኬራቲን
العربية: كيراتين
български: Кератин
bosanski: Keratin
català: Ceratina
čeština: Keratin
dansk: Keratin
Deutsch: Keratine
eesti: Sarvaine
English: Keratin
español: Queratina
Esperanto: Keratino
euskara: Keratina
français: Kératine
Gaeilge: Ceiritin
galego: Queratina
한국어: 케라틴
Հայերեն: Կերատիններ
hrvatski: Keratin
Bahasa Indonesia: Keratin
italiano: Cheratina
עברית: קרטין
Kreyòl ayisyen: Keratin
lietuvių: Keratinas
magyar: Szaru
Bahasa Melayu: Keratin
မြန်မာဘာသာ: ကီရာတင်
Nederlands: Keratine
日本語: ケラチン
norsk: Keratin
norsk nynorsk: Keratin
occitan: Queratina
polski: Keratyny
português: Queratina
русский: Кератины
Scots: Keratin
slovenščina: Keratin
کوردی: کێراتین
srpskohrvatski / српскохрватски: Keratin
Basa Sunda: Keratin
suomi: Keratiini
svenska: Keratin
தமிழ்: நகமியம்
Türkçe: Keratin
українська: Кератини
اردو: قرنین
Tiếng Việt: Keratin
粵語: 角蛋白
中文: 角蛋白