Anatomy
I
Iridophore
/ /ɪˈrɪdəfɔː/ /
Quick Definition
A light-reflecting cell containing crystalline guanine platelets that produce iridescent or mirror-like coloration in fish.
📖 Full Definition
Iridophores are a type of chromatophore that contain stacks of thin, crystalline guanine platelets oriented in layers. These act as interference reflectors, producing structural colours through thin-film interference. Depending on the orientation of the platelets, iridophores can appear silver, gold, blue, or green. The silvery flanks of pelagic fish are produced by iridophores containing a dense palisade of platelets parallel to the skin surface, creating a mirror that reflects ambient light and disrupts the fish's silhouette from predators.
💡 Examples & Context
The mirror-like silver flanks of a fresh Atlantic herring are caused by iridophores. The colour fades within minutes of death as the cells lose structural integrity.