The giant barrel sponge is a large sponge that lives on coral reefs around the Caribbean Sea and adjacent waters. Reaching sizes of at least 6 feet (1.8 m) across, this is one of the largest sponge species wherever it lives. Its bowl-shaped body (open at the top, closed at the base) provides habitat for many other species of invertebrates (including crabs and shrimps) and fishes (including gobies, cardinalfishes, and other species). Giant barrel sponges, like all sponges, are attached to the reef surface and are unable to move. Like most sponges, this species has a glass-like skeleton.
Together, the sponges make up one of the oldest, most primitive groups of animals on Earth. Sponges have existed for at least 500 million years. Sponge cells do not have specialized purposes. Each of a sponge’s individual cells can transform to complete the job of any other cell in the body. This lack of specialization means that sponges do not have tissues, like every other type of animal. In fact, in laboratory settings, a sponge that is destroyed in a blender can reform itself as the cells swim back together and take on the form and job needed for recovery. Giant barrel sponges feed by filtering water through the body wall, trapping food particles and excreting waste materials into the inner bowl. The, now filtered, wastewater exits the sponge through the large opening at the top (called an osculum). They also obtain oxygen from the water during this process.
Giant tube sponges are hermaphroditic – each individual produces both eggs and sperm. They release large clouds of sperm into the water column but do not release the eggs. Instead, through their filter-feeding behavior, they filter out sperm from other individuals and fertilize the eggs inside their bodies. After the eggs mature, larvae are released into the water column, through the osculum, and eventually settle to start growing into new sponges. Giant tube sponges can live as long as 2000 years (and probably much longer).
The conservation status of the giant tube sponge is unknown. However, because this species lives mostly on coral reefs, changes to that fragile system caused by irresponsible human behavior may threaten this sponge.
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