Sea Pen

ocean · colonial animals · bioluminescence

Feathery ocean dwellers. Sea pens are soft, fleshy animals that look like giant feathers stuck in the mud on the seafloor. They're actually made of thousands of tiny creatures called polyps living together as one colony.

They glow in the dark. Many sea pens can make their own light through a process called bioluminescence, creating beautiful blue or green glows when disturbed. Scientists think they use this light to scare away hungry fish and other predators.

Found everywhere underwater. Sea pens live in oceans all around the world, from shallow tropical waters where sunlight reaches, all the way down to the dark depths over 20,000 feet below the surface where it's freezing cold.

Anchored to the bottom. Each sea pen has a special root-like structure that digs into sand or mud on the seafloor, keeping it in one spot even though ocean currents push and pull at it.

Tiny hunters of the sea. The polyps covering a sea pen catch tiny food particles and plankton floating by in the water, filtering them out with little tentacles that surround their mouths.