02/05/2026
The bobtail squid is a small ocean animal with a very unique survival trick. Instead of making its own light, it uses glowing bacteria to help it disappear in the water. This special teamwork helps the squid avoid predators while it hunts at night.
During the daytime, the bobtail squid hides by burying itself in sand. When night comes, it swims out to look for food like shrimp and tiny crustaceans. Light from the moon and stars shines down into the water, which would normally create a shadow under the squid. Predators below could easily spot that shadow. To prevent this, the squid uses light from its belly to cancel out the shadow.
The light comes from bacteria called Vibrio fischeri. These bacteria live inside a special light organ on the squid’s underside. When they glow, their light matches the brightness of the moonlight above. This makes the squid almost invisible from below. This process is called counterillumination.
Baby bobtail squid are born without the bacteria. Soon after hatching, they collect the bacteria from seawater. Once inside the squid, the bacteria grow quickly. The squid gives them food, oxygen, and a safe place to live. In return, the bacteria provide light. This type of relationship is called mutualism because both sides benefit.
The squid can control how bright the light is by adjusting tissues around the light organ. Each morning, it releases most of the bacteria, then allows the remaining ones to regrow by nightfall.
Scientists study the bobtail squid to learn how animals and helpful bacteria work together. This tiny squid shows how cooperation in nature can be just as powerful as strength or speed.
via: dailydosagewildlife / tt
