Bobtail Squid

ID points

• Body short and round like a pouch, with two small rounded ear-like fins
• Symbiotic glowing bacteria make the underside faintly luminous at night
• By day it hides by sticking sand grains to itself with mucus

Basics

Family

Sepiolidae

Length

3–7 cm

Depth

0-100 m

Regions

Indo-Pacific reefs

Distribution

Sandy bottoms in shallow tropical seas

Habitat

Shallow tropical sandy bottoms

Diet

Small shrimp, small fish

Easily confused with

Blue-ringed OctopusElectric blue rings flare over the whole body when it is provokedLongnose FilefishEmerald green ground covered with orange square patchesSharpnose PufferLong pointed snout; slimmer than an ordinary puffer

Fun fact

The Bobtail Squid houses the glowing bacterium Aliivibrio fischeri inside its light organ. Those bacteria let it produce bioluminescence at night, cancelling out the shadow it would otherwise cast in the moonlight so that predators below cannot pick it out.