“Luminescence,” “fluorescence” and “bioluminescence.” These are all words you’ll be hearing and seeing around the Aquarium this winter, but what the heck do they mean?

Luminescence is the name of our feature exhibit. The internet tells me it means “the emission of light by a substance that has not been heated…” We’re featuring animals (both marine and terrestrial) that glow in the dark and under light.

Fluorescence occurs when light is absorbed as one colour and re-emitted as another colour – there has to be light present for fluorescence to happen. Some fishes can see fluorescence in sunlight because they can see into the ultraviolet (UV) spectrum. But we can’t, so that’s why we need additional UV light to see objects or animals fluoresce.

Clonal anemones under white light.

Clonal anemones under white light.

For example, take a clonal anemone (Anthopleura elegantissima). In sunlight, we see its pink tentacle tips. But when a UV light is shone on it – it glows green.

Bioluminescence, on the other hand, occurs in the absence of light – that is, in the dark.



Bioluminescence takes place when two naturally occurring chemicals inside an organism’s body react to create light. Deep-sea anglerfishes are famous for the dangling lures of bioluminescent light that extend from their heads (although these fishes actually “borrow” their light – they host bioluminescent bacteria in those lures.)

It’s complicated, we know. Still not quite sure what this all means?

Watch the video below.


Written by Karen Horak, writer-editor, content and digital experience at the Vancouver Aquarium.

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