The harp sponge is the sort of thing you look at and just think “this exists.” A lot of deep-sea life fits that category, but just look. A harp, upside-down chandelier, or whatever you want to see, it’s thing created by nothing more than chance and selection — and that’s awesome. While first identified by researchers using a remote-operated vehicle in 2000, the creature was described only last month in a paper in Invertebrate Biology, courtesy of the Monterey Bay Aquarium Research Institute and its two ROVs, Tiburon and Doc Ricketts. You may remember the Institute from such discoveries as the Pigbutt worm and the self-farming Yeti crab.The harp sponge isn’t actually going to eat your face , but one of its claims to notability is that it’s a meat-eater. Which is unusual: most sponges live off of bacteria and assorted organic floaties. This one actually snares small fish and crustaceans with small velcro-like hooks, then coats them in a thin membrane and slowly digests them. The balls at the end of the sponge’s spires don’t actually have anything to do with the process. Rather, this is where the harp’s sperm is created and released. The structures about halfway down on the spires are where their eggs hang out.A post at Nature.com has a bit of background:Seventeen years ago, Jean Vacelet and Nicole Boury-Esnault from the Centre of Oceanology at France's Aix-Marseille University provided the first real evidence that a sponge could be more than, well, a sponge. They had discovered a new species of deep-sea sponge living in the unusual setting of a shallow Mediterranean sea cave, the inside of which mimicked the conditions of its usual habitat more than a kilometre below the surface. This allowed the researchers an unprecedented view of the sponge's eating habits, and they watched as it snared its prey of small fish and crustaceans instead of absorbing bacteria and organic particles through their bodies, like most other sponge species do – including ones living in the very same cave.
Vacelet and Boury-Esnault's sponges were of the Asbestopluma genus and belonged to the Cladorhizidae family of carnivorous demosponges – the class that contains over 90 percent of the world's sponges. Since reporting their discovery in a 1995 issue of Nature, 24 new species of cladorhizid sponges, including the incredible ping-pong tree sponge, have also been discovered. Yet due to the difficulty of studying their behaviour at such incredible depths, researchers have had little opportunity to describe essential aspects of their lives, particularly how they reproduce.Fortunately, MBAR and its deep-sea vessels are there to provide that opportunity. And we can all be a little more baffled by reality.Reach this writer at michaelb@motherboard.tv.
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