A Strange, Meat-Eating Sea Sponge in the Deep Ocean

Sort of an under water Venus Fly Trap?

The harp sponge (Chondrocladia lyra) can indeed be likened to an underwater Venus flytrap due to its specialized adaptations for capturing prey. Much like the carnivorous Venus flytrap and sundew plants, the harp sponge is designed to ensnare small living organisms drifting by in deep-sea currents. Its branching limbs are covered with fine, hook-like projections known as spicules, which function similarly to Velcro, effectively snagging tiny crustaceans and other small marine creatures that come into contact with them. Once prey is captured, the sponge envelops it in a thin membrane and begins the digestion process, breaking down the organic material for nutrient absorption. This feeding mechanism contrasts sharply with most sponges, which typically filter-feed on microscopic particles in the water.

A New Carnivorous Sponge Discovered in Monterey Bay

A remarkable carnivorous sponge resembling a candelabra, known as the “harp sponge” (Chondrocladia lyra), has been observed in the deep ocean waters off California’s Monterey Bay. This species was first discovered in 2000 by a team from the Monterey Bay Research Aquarium Institute using remotely operated vehicles (ROVs) during explorations nearly 2 miles below the ocean’s surface.

Lonny Lundsten, an invertebrate biologist at the institute and one of the initial observers of this sponge, expressed his astonishment, stating, “No one had ever seen this animal with their own eyes before.” The harp sponge’s unique structure allows it to capture prey effectively; its branching limbs are covered with Velcro-like barbed hooks that ensnare tiny crustaceans as they are swept into its branches by deep-sea currents. Once captured, the sponge envelops its prey in a thin membrane and digests it slowly.

Initial findings revealed sponges with only two branches, or vanes, but further ROV dives uncovered specimens with up to six vanes, with the largest recorded at approximately 14 inches tall. This elaborate structure is believed to enhance the sponge’s ability to capture more prey by increasing its exposure to ocean currents. The sponge anchors itself to soft, muddy sediments on the ocean floor using root-like structures called rhizoids.

Recent research published on October 18, 2023, in the journal Invertebrate Biology has provided insights into the life cycle and reproductive methods of C. lyra. Unlike most sponges that release free-swimming sperm into the water, harp sponges transfer sperm in condensed packages called spermatophores. These packets are released from swollen terminal balls at the tips of their branches and can be captured by nearby sponges for fertilization.

Lundsten noted that despite having explored only 1% of Monterey Bay, it remains one of the most well-studied deep-sea regions on Earth, suggesting that many more undiscovered species may inhabit these waters. The harp sponge is one of four new species Lundsten has helped identify since its discovery.

Risk to Humans

While the harp sponge (Chondrocladia lyra) is a fascinating deep-sea predator, it poses no threat to humans. The sponge’s method of capturing prey involves using its Velcro-like barbed hooks to ensnare small fish and crustaceans as they are swept into its branches by ocean currents. Given its habitat, nearly 2 miles underwater, human encounters with this species are exceedingly rare. In the unlikely event that a person were to come into contact with a harp sponge, they would likely be able to break free due to their size and the sponge’s relatively weak grip compared to larger marine predators. The sponge primarily targets small marine organisms, and its adaptations are specifically designed for capturing prey much smaller than a human, making any risk to people virtually nonexistent.

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[1] https://www.sci.news/biology/article00703.html
[2] http://novataxa.blogspot.com/2012/11/2012-chondrocladia-lyra.html
[3] https://www.cbsnews.com/news/strange-meat-eating-sea-sponge-found-in-deep-ocean/
[4] https://en.wikipedia.org/wiki/Chondrocladia_lyra
[5] https://www.nature.com/articles/nature.2012.11789