Although us to know the deep sea is weird, the “carnivorous sea sponges” still sound like something out of a science fiction movie. However, researchers have just announced the discovery of three new species of this type off the coast of Australia.
Go a few hundred meters deep into the ocean and it begins to look like you’re in a whole new world: from a creature that looks like a starfish crossed with an octopus, to shark-eating fish, to carnivorous sponges. I’ve never seen it before.
It simply demonstrates how much of our deep oceans have not yet been explored (these particular sponges are quite unique, as they are only found in this region of The Great Australian Bight), a region that was planned for oil exploration in deep waters, ”said one of the researchers, the manager of Queensland’s Sessile Museum marine invertebrate collection, Merrick Ekins.
Typically, sea sponges feed on multicellular filters: they have perforated tissues for flowing water, from which their cells extract oxygen and food. They are fairly simple creatures, with no nervous, digestive, or circulatory system, but that have existed in some way for over 500 million years.
Scanning electron microscope image of Oxycars of the Acarnidae. (Ekins et al., Zootaxa, 2020)
But carnivorous sponges are a little different. Some carnivorous sponges still use the water flow system, while others (such as the three newly discovered species) have lost this ability altogether and capture small crustaceans and other prey with filaments or hooks.
The researchers in this study found three new species of carnivorous sponges: Heptaxia Nullarbora, Oxychasts of the Acarnidae i Lycopodina hystrix, which are also new genera, as well as a closely related non-carnivorous sponge species, Guitar davidconryi. All of these species were found at depths between 163 and more than 3,000 meters deep.
“Here we report on four additional new species of sponges discovered in the Great Australian Bight, South Australia. This area has recently been inspected, using a Grab-Smith-McIntyre and a Vehicle Operated Remotely (ROV) to photograph and harvest marine biota, ”the researchers write in their new article.
“These new species are the first recorded carnivorous species in South Australia and increase the number of recorded species across Australia to 25.”
Sponges are also prettier than you might imagine, looking a bit like flowers with their prickly protrusions, but not like sponges.
Close-up of A. oxiaster. (Ekins et al., Zootaxa, 2020)
Carnivorous sponges pass for a while. We have known about it since 1995, but many more have recently been discovered around the world.
“Over the past two decades, our knowledge about the diversity of carnivorous sponges has almost doubled,” the same team explains in a previous paper, which described the discovery of 17 new species of carnivorous sponges.
“[This is] due, in part, to rapid advances in deep-sea technology, including ROVs and submarines capable of photographing and harvesting intact carnivorous sponges, and also to the Herculean efforts of a number of contemporary taxonomists who redescribe many of the older species described. in the 19th and 20th centuries “
Almost every species of carnivorous sponge found in Australia was discovered during a CSIRO RV researcher trip in 2017, which shows the importance of this research in deep water.
With the ocean floor still almost unexplored, imagine that we will see many more species of carnivorous sponges and other strange and wonderful sea creatures.
The research has been published in Zootaxa.