Growing from the rocks on a long stalk, the Sea Tulip is commonly encountered by divers around Sydney.
The Sea Tulip is covered in lumps and bumps, giving it a kind of warty appearance. It comes in a variety of colours such as orange, purple, yellow or pink. These bright colours aren't the work of the Sea Tulip but are from an encrusting sponge, Halisarca australiensis, which covers its surface.
The Sea Tulip is found in coastal waters to a depth of 80 m.
Feeding and diet
The Sea Tulip is sessile (unable to move around) and so waits for the currents to bring food to it. Like all sea squirts, the Sea Tulip is a filter feeder, pumping water in and out of its siphons and extracting the plankton.
Other behaviours and adaptations
Many sponges contain compounds to deter predators. In the relationship between the Sea Tulip and the encrusting sponge, the Sea Tulip gains protection from predators by using the sponge's defence, and the sponge benefits by having a surface on which to grow.