The oldest living animal group on earth, sponges are known to have existed for over 600 million years. They are remarkably diverse, with the number of species estimated at over 25 000. Sponge grounds are themselves complex ecosystems and sponges also play a crucial role in the functioning of wider deep-sea ecosystems.
Although ubiquitous in deep sea and of huge ecological importance, sponges have been largely overlooked in research and conservation work. Often found in areas such as shelves, slopes, ridges, canyons and fjords, they are vulnerable to human activities such as fishing, mining for minerals or drilling for oil and gas.