colloblast

Colloblasts are specialized secretory cells located on the tentacles of most ctenophores (comb jellies). Each colloblast contains an adhesive granule, and when prey contacts a tentacle, the cell discharges the granule to release a sticky substance that coats the prey and the tentacle surface. The resulting adhesion helps the prey attach to the tentacle long enough for the ctenophore to bring it toward its mouth. This mechanism is a form of passive prey capture and is distinct from the venomous stinging cells of cnidarians.

Colloblasts are a defining feature of ctenophores and are found in high density on the tentacles and, in some species, on specialized structures called tentilla. The adhesive is thought to be a protein-based substance, possibly with mucopolysaccharide components, but the precise chemical composition and discharge mechanism are still the subject of research. Unlike nematocysts, colloblasts do not deliver toxins or stings.

Studies of colloblasts contribute to broader interests in marine biology and materials science. The rapid, seawater-friendly adhesion exhibited by colloblasts has inspired investigations into bioadhesives for wet environments and potential biomimetic applications.