Phyllidia coelestis, a sea slug
© Jurgen Freund/Aurora Photos
Phyllidia coelestis, a sea slug
This sea slug, usually less than 2.5 inches long, crawls along the sea floor of the Pacific and Indian Oceans at depths of nearly 100 feet. The strange colour and markings have a purpose: It’s a warning to predators. Aposematic colouring, as this is called, usually indicates that an animal is either poisonous or doesn’t taste good. It’s an easy way to avoid becoming prey. Honestly, we aren’t hungry. We just like that this sea slug’s markings make it look like a rubber monster mask, cast off after a long night of Halloween fun.
Related Images
Bàu Cá Cái mangrove forest in Quảng Ngãi Province, Vietnam
Dubai Miracle Garden, United Arab Emirates
Lanterns at Datang Furong Garden, Tang Paradise in Xi'an, China
Christmas decorations in Warsaw, Poland, for Christmas Day
Oil lamps being arranged on rangoli during Diwali
Autumn leaves and goldfish in Tokyo, Japan
The Brandenburg Gate seen through a heart-shaped replica of the Berlin Wall, Berlin, Germany
Spanish shawl nudibranch on kelp off Santa Catalina Island, California, USA
Bing Today Images
Camels at Jaisalmer, Rajasthan, India
Oct 30, 2025
Common raven sitting on a branch
Oct 30, 2023
The sun sets over the Eastgate Clock in Chester.
Oct 30, 2022
Blakiston's fish owl in Hokkaido, Japan
Oct 30, 2020
Charles Bridge over the Vltava River in Prague
Oct 30, 2019
Tunnel in Yosemite National Park, California, USA
Oct 30, 2017
