Invertebrates
Japetella
Japetella diaphana · also called gelatinous octopus
Nearly invisible as a juvenile and darkly coloured as an adult, Japetella switches strategies entirely as it grows, trading transparency for a bioluminescent flash meant to startle rather than hide from a predator in open water.
Overview
Japetella, Japetella diaphana, is a soft-bodied, open-water octopus native to tropical and temperate ocean habitat recorded across multiple ocean basins worldwide. Its dramatic colour change from transparent juvenile to dark reddish-brown adult, shift from camouflage to bioluminescent defence, and open-water lifestyle make it one of the more behaviourally distinctive cephalopods found anywhere in the deep sea.
Two different survival strategies in one lifetime
Rather than sticking with a single defensive strategy throughout its life, Japetella appears to switch tactics entirely as it matures, relying on transparency while small and vulnerable before turning to a startling burst of bioluminescent light once camouflage alone is no longer enough to hide its darkened adult body.
Status
Least Concern, though population trends remain largely unknown given the difficulty of surveying deep-sea habitat.
Japetella: common questions
Why does Japetella change colour as it grows?
This species is nearly transparent as a juvenile, gradually darkening into a dense reddish-brown colour as it matures into an adult, a dramatic shift thought to reflect a change in how it avoids predators at different life stages.
Does Japetella rely on camouflage to avoid predators?
Only as a juvenile, once it has darkened into an adult it is thought to rely more on bioluminescent flashes to startle or confuse a predator rather than on blending into its surroundings.
Does Japetella live on the seafloor?
No, this species spends its life drifting through open ocean water rather than crawling across the seafloor, a lifestyle shared with several other deep-sea octopus species.
How deep does Japetella live?
This species has been recorded from several hundred metres down to well over a thousand metres, adjusting its typical depth somewhat as it matures from a juvenile into an adult.