The harp sponge: an extraordinary new species of carnivorous sponge

Scientists from the California Academy of Sciences, the University of Victoria, the Khoyatan Marine Laboratory, and the Monterey Bay Aquarium Research Institute recently described an extraordinary new species of carnivorous sponge, named Chondrocladia lyra, or the harp sponge. Rather than filtering water for food, as most sponges do, carnivorous sponges ensnare tiny animals with small, Velcro-like hooks and spines. The sponges then envelop and digest their prey. In fact, enclosed and partially digested crustacean prey were observed embedded in tissues of the sponges we collected for this study. MBARI's remotely operated vehicles Tiburon and Doc Ricketts were used to collect two specimens of the new sponge. We used these specimens, along with video observations of 10 other individuals to describe the unique morphology of this sponge and to characterize the habitat and environment where it lives. These sponges were observed on the deep seafloor off the coast of California. They live on soft, muddy sediment at depths of 3300 – 3500 meters, where environmental conditions, including food sources, are extremely stable. The harp sponge anchors itself into the soft sediment with a root-like structure called a rhizoid. Other organisms, including anemones and sea cucumbers, were observed near the harp sponges. We named this unique animal a harp sponge because the shape of the vane and the vertically aligned branches resemble a harp. Like sea-fan corals, we think the harp sponge evolved into this shape to maximize the surface area that is exposed to prevailing currents. This increased surface area probably helps the sponge capture prey and release its eggs and *** into passing ocean currents. The first specimens we encountered showed only two vanes. However, additional observations revealed that the harp sponge often has multiple vanes; up to six have been observed, and these all radiate from the center of the organism. The upright branches of each vane typically end in a swollen ball, which is where packets of *** are produced and released. When *** packets released from other, nearby sponges are captured on egg development sites of vertical branches the area become swollen as the fertilized eggs mature. In addition to studying the new sponge’s morphological characters and ecology, we used powerful microscopes to describe the shape and size of species-specific structural elements called spicules. Close examination and description of spicules is essential to species identification in sponges. Our observations suggest that a related species of sponge may occur in deep waters of the south Atlantic. This unique discovery aids in our understanding of carnivorous sponge biology and enhances our knowledge about deep-sea biodiversity. At MBARI this is Lonny Lundsten.