The bottom of the ocean really is an alien world, less well-mapped than Venus, inhabited by species that look like visitors from other planets. Some indeed look like specific imaginary aliens, including a newly described glass sponge that bears a striking resemblance to the star of the 1982 blockbuster, E.T. – The Extra-terrestrial.
The species, now named Advhena magnifica, lives on Pacific Ocean seamounts. It was first collected in 2016 by the Okeanos Explorer's study of mounts near the Mariana Trench, but that expedition took so many samples it sat at the Smithsonian National Museum of Natural History unstudied until 2017, when the Explorer filmed what marine biologists called the “Forest of the Weird”. There, among other strange organisms that inspired the name, the Explorer’s operators saw what looked like a familiar face – sponges with a spooky resemblance to ET.
Dr Cristiana Castello Branco of the Smithsonian set about describing the invertebrate. Her work has now been published in PeerJ, including the scientific name of the new sponge, Latin for "magnificent alien".
In an interview for the NOAA website Branco noted that to the Romans, alien meant “visitor, foreigner or immigrant”, adding, “Of course we, humans, were the actual visitors to the sponge’s deep-sea home.”
The key to the resemblance is the two holes that look like ET’s giant eyes. Living at depths where light barely reaches, glass sponges have no vision, and lack a central nervous system to process the information eyes provide anyway. Instead, these are oscules, the openings through which the sponge expels water after it has been drawn in through smaller holes with food particles removed in a network of canals and chambers. The impression is reinforced by the long stalk that gives A. magnifica access to more food-rich waters, but looks a little like ET's neck.
We know little about A. magnifica’s place in its deep-sea ecosystem, but sponges, like corals, provide habitats for other species, making the places where they grow biological hotspots. In addition to A. magnifica, the paper describes two new species; Euplectella sanctipauli and Bolosoma perezi discovered in the South Alantic. Bolosoma sponges have never before been reported in the Atlantic Ocean. Besides not looking like anyone famous, this pair are members of existing genera, unlike A. magnifica, which is so different from anything previously recorded Branco judged it as needing a genus of its own.
Most sponges live at depths of 450-900 meters (1500-3,000 feet), but A. magnifica was collected 2,028 meters (7,000 feet) down and E. sanctipauli at almost twice that. All are known as glass sponges because their skeletons are made of silica.
Sponges cannot flee from danger, so they fight off enemies using chemical warfare. The molecules they produce could be a treasure trove in the quest for new medicines.