Related to the non-synthetic sponges seen in kitchens and bathrooms, the four new species were discovered from the Pacific Northwest to Baja California by marine biologist Lonny Lundsten of Monterey Bay Aquarium Research Institute along with two Canadian researchers. The team videotaped the four new sponges that thrive on the seafloor. For further taxonomic work, samples of the sponges were collected.
This is a major finding as it was some 20 years ago that scientists first discovered carnivorous sponges. Since the first finding, scientists have successfully identified seven carnivorous species and all of them were found in the northeastern Pacific.
Similar to small shrubs or twigs, these animals are enveloped in tiny hairs and these contain tightly packed minute hooks that help the sponge trap its prey. The cells of the sponge engulf and digest the trapped animal in a few hours. After days, it is just an empty shell that is left.
Known to be filter feeders, sponges have specialized cells called choancytes. But the carnivorous sponges do not have choancytes.
Lundsten explained, "To keep beating the whip-like tails of the choancytes takes a lot of energy. And food is hard to come by in the deep sea. So these sponges trap larger, more nutrient-dense organisms, like crustaceans, using beautiful and intricate microscopic hooks."
On examining the samples, researchers saw numerous crustaceans prey that were present in several states of decomposition.
Out of the four sponges, two had spines. The two belong to the genus Asbestopluma. One of the Asbestopluma monticola was collected from the top of Davidson Seamout, extinct underwater volcano. Monitcola in Latin means mountain-dweller.
The second new species of killer sponge is named after marine biologists Ed Ricketts and is called Asbestopluma rickettsi. The new species of sponges were seen at two different locations offshore of Southern California. One sponge was found close to a colony of clams and tubeworms that use bacteria to get the nutrition from methane seeping out of seafloor. Even this sponge had spines but no animals were trapped in it.
Research revealed that the sponge uses bacteria as food source, similar to its chemosynthetic neighbor.
The other two new species of carnivorous sponge were seen near communities of chemosynthetic animals. One sponge called Cladorhiza caillieti was seen on a recent lava flow along a volcanic ridge off shore of Vancouver Island.
The fourth one, baptized Cladorhiza evae, was seen in a hydrothermal vent field off the tip of Baja California. Both these sponges had several prey engulfed in their spines.
At the moment, the researchers are unclear whether the sponges that had animals trapped in their spines were consuming their crustacean prey. They hope to resolve this mystery in future studies.
"Numerous additional carnivorous sponges from the Northeast Pacific (which have been seen and collected by the authors) await description, and many more, likely, await discovery," the authors noted.
The discovery of the new carnivorous sponges was reported in the journal Zootaxa.
