But that changed when it was revealed that sponges could move. Sponges were thought to be unresponsive to outside stimuli and, well, very plantlike. Today there are 6,000 known species and new ones being identified regularly. Sponges evolved more than 500 million years ago, flourished through Earth’s great extinction events, and have endured ever since. But new accidental findings may show we’ve underestimated them. They’re also the least evolutionarily advanced creatures on the planet. Sponges may look like plants, but they’re animals-some of the longest-lived on Earth, with a few living more than 10,000 years. Or are sponges able to move faster sporadically? Credit: AWI OFOBS team, PS101 With paces of just millimeters per year, some tracks may have taken hundreds of years or more to create. After the eggs mature they themselves are released to find their way to move on and form new sponges.Sponge-spicule trails are typically tan and may move uphill and change directions like this one. They can then use this filtered sperm (from other sponges) to fertilize the eggs in their own bodies. While the sponge holds onto the eggs, clouds of sperm are released into the water column and are filtered out by the same process as the barrel sponge uses for food and oxygen. Giant tube sponges on the other hand are hermaphroditic, producing both eggs and sperm at the same time. Given time though, the individual cells will find a workaround so that water flow will resume and the sponge will continue to grow. If for example, a clumsy diver kicks or bumps into a barrel sponge, the crushed cells on the sponge may well stop water flow through the wall and whole sections of the sponge will die off. Remember that the sponge itself is thousands or millions of cells working together to enable this process to happen, each able to change its task as required. The materials that they don’t need are excreted into the “bowl” in the middle. The freshly filtered water is the ejected from the osculum, (the large hole at the top). By filtering oxygen and particulate out of the water for food, they make a pretty efficient filtering / eating machines. Giant barrel sponges, like we find in Nusa Lembongan, feed by filtering water through the wall of the body by whipping their flagellum.
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