Invertebrates
Bobtail Squid
Euprymna scolopes · also called Hawaiian bobtail squid
Burying itself in sand by day and hunting by night, a bobtail squid carries a colony of glowing bacteria inside its own body, tuning the light to match the faint glow of the moon above and erasing its silhouette from predators below.
Overview
The bobtail squid, Euprymna scolopes, is a small, bioluminescent cephalopod native to coastal ocean habitat recorded around the Hawaiian Islands. Its remarkable bacterial light-organ partnership, status as a leading scientific model for animal-microbe symbiosis, and nightly camouflage strategy make it one of the most scientifically influential small cephalopods found anywhere in the ocean.
A partnership that shaped an entire field of science
The bobtail squid’s relationship with its glowing bacterial partners has become one of biology’s clearest windows into how animals and microbes establish lasting, mutually beneficial relationships, insights that reach far beyond this one small squid and its Hawaiian coastal home.
Status
Least Concern, remaining widespread and stable across suitable coastal ocean habitat around the Hawaiian Islands.
Bobtail Squid: common questions
How does the bobtail squid use bacteria to hide from predators?
This species hosts a colony of bioluminescent bacteria within a specialised light organ, using the resulting glow for counter-illumination that matches moonlight or starlight filtering down from above, helping erase its silhouette from predators hunting below.
Is the bobtail squid born with its glowing bacteria already present?
No, this species acquires its light-producing bacteria fresh from the surrounding seawater shortly after hatching, rather than inheriting them directly from its parents.
Why is the bobtail squid so important to science?
This species is one of the most studied examples of a beneficial partnership between an animal and bacteria, providing key insights into how such symbiotic relationships establish and are maintained across many other organisms.
What does the bobtail squid do during the day?
This species buries itself in sand during daylight hours, emerging at night to hunt when its bioluminescent camouflage becomes useful against nocturnal predators relying on faint moonlight or starlight.