Urn Ascidian or Green Barrel Sea Squirt
Scientific name: Didemnum molle
Description: The urn ascidian grows in groups on dead coral or rock found in reefs in the Indo-Pacific ocean. The body is urn-like with a small hole on top allowing filtered water out, while the smaller holes covering its body take in water. The exterior is a brown and white opaque color while the interior of the animal can be a bright green color due to the symbiotic photosynthetic blue-green algae living inside their tissues. Aside from receiving nutrients from the algae, the tunicate or sea squirt also feeds on plankton by filtering them out of the water.
Fun Facts:
- The tunic or body produces mycosporins which act as a shield against UV light and therefore help the blue-green algae inside them not die!
- Tunicates may seem like very simple organisms but they are actually related to vertebrates. They have a dorsal nerve cord!
