Tunicates (sea squirts)
Brightly coloured filter-feeding marine invertebrates. They are often found on live rock. Some are beautiful, others haunting.
Detailed explanation
Tunicates (sea squirts) are sessile invertebrates that filter water to feed on phytoplankton and organic particles.
Some species are decorative: the blue sea squirts (Rhopalaea crassa), the orange sea squirts (Polycarpa aurata) are spectacular but difficult to maintain because they require feeding with phytoplankton.
Other species arrive as stowaways on live rock and can become weeds: Didemnum are whitish colonies that cover the surfaces.
Reef safe tunicates do not harm corals and can add colour and interest to the aquarium. Infesting ones must be removed manually.