spongin

biochemistry

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July 14, 2026

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Spongin is a scleroprotein, a type of protein, that is the main component of the flexible fibers found in the skeletons of certain sponges. It is similar to keratin, a protein found in the skin, claws, hair, and feathers of other animals. There are two types of spongin, A and B, which vary in their composition and structure. Sponges are unusual animals as they lack distinct organs, relying instead on a water-current system for functions like feeding, respiration, and waste removal. They also produce substances with antibiotic activity and contain a diverse range of fatty substances, pigments, and accumulate various elements.12

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sponge
Other types
…(Ceractinomorpha) has a type of spongin, which, in certain orders (Axinellida, Poecilosclerida, and Haplosclerida), cements the spicules in bundles or meshes, thereby increasing the elastic nature of the skeleton. In another group of Demospongiae (Keratosa), spongin fibres constitute the entire skeleton; the spongin fibres may be branched (order Dendroceratida), netlike…
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…(Ceractinomorpha) has a type of spongin, which, in certain orders (Axinellida, Poecilosclerida, and Haplosclerida), cements the spicules in bundles or meshes, thereby increasing the elastic nature of the skeleton. In another group of Demospongiae (Keratosa), spongin fibres constitute the entire skeleton; the spongin fibres may be branched (order Dendroceratida), netlike…
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