Large sessile habitat-forming organisms such as sponges, corals, bryozoans and hydroids play a crucial role in the structure of Antarctic marine communities and enhance the local biodiversity. Not only are there many species of these groups found in the Antarctic (387 sponges, 141 corals, 320 bryozoans and 337 hydroids) but they also form vital habitats for countless other organisms. The habitats formed by these megafaunal organisms are increasingly being recognized as both vulnerable and important ecosystems. The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) adopted a proposal to declare two areas of the Southern Ocean as Vulnerable Marine Ecosystems (VMEs). Both areas proposed are highly biodiverse, particularly with respect to habitat-forming hydrocorals, sponges and associated fauna.