Details
Euprymna scolopes
The Hawaiian bobtail squid is a small seafloor squid famous for its partnership with light-producing bacteria. By matching moonlight from below, it hides its shadow at night.
Map: Ecoregions 2017 © RESOLVE (CC BY 4.0) · Natural Earth (PD)
It lives in Pacific coastal waters around Hawaii, especially sandy bottoms near reefs. By day it buries in sand, emerging over shallow seabeds at night.
Length 2-4 cm; weight 1-8 g. It has a rounded body, large eyes, short arms, and rapid color change. A light organ on the underside controls a soft blue-white glow.
Nocturnal and solitary, it spends daylight covered with sand. At night it swims and adjusts bacterial light to match the brightness overhead.
A carnivore, it catches small shrimps and other crustaceans. The arms seize prey, and a beaklike mouth cuts it apart.
Females attach eggs in sheltered bottom spaces. Hatchlings acquire luminous bacteria from seawater and establish the light-organ symbiosis early in life.
It is listed as Least Concern. The species is a key model for studying how animals and beneficial microbes form partnerships.
