Colloblasts are a cell type found in ctenophores. They are widespread in the tentacles of these animals and are used to capture prey. Colloblasts consist of a coiled spiral filament that is embedded in the epidermis and an axial filament with a granular dome. The apical surface of these cells consist of eosinophilic granules that are thought to be the source of adhesion. On contact, these granules rupture, and release an adhesive substance onto the prey. The spiral filament absorbs the impact of the rupture preventing the ensnared prey from escaping. Colloblasts are found in all ctenophores except those of the order Beroida, which lack tentacles, and the species Haeckelia rubra, which utilize cnidocytes from cnidarian prey.
Like the cnidocytes of cnidarians, colloblasts are discharged from the tentacles and are used for prey capture. However, unlike cnidocytes, which are venomous cells, colloblasts stick to, rather than sting their prey.
Colloblasts were first observed in 1844.
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