Natural sea sponges are among the ocean’s most ancient and fascinating creatures. Despite their simple appearance, these animals—yes, they are animals, not plants—hold a wealth of biological secrets and ecological importance. With a lineage stretching back over 600 million years, sea sponge (phylum Porifera) is one of the oldest forms of multicellular life on Earth.
What Are Natural Sea Sponges?
Sea sponges are sessile marine animals, meaning they are attached to surfaces like rocks, coral, or the seafloor and do not move around. They come in various shapes, sizes, and colors, and their bodies are made of a porous matrix that allows water to flow through them. This structure is key to how they survive.
What Do Sea Sponges Eat?
Sea sponges feed by filtering microscopic particles from the water—a process called filter feeding. Tiny openings on their surface, called ostia, let in water, which flows through internal canals. Specialized cells known as choanocytes use whip-like flagella to create currents and trap plankton, bacteria, and organic debris. The sponge then absorbs nutrients and expels the filtered water through a larger opening called the osculum. A single sponge can filter thousands of liters of water per day.
How Do They Move?
Though they appear completely still, sponges exhibit a slow and subtle form of movement. As larvae, sponges are free-swimming and move using small hair-like structures called cilia. This mobile stage lasts just a few hours or days before they settle onto a surface and grow into their adult, immobile form.
Adult sponges don’t move in the traditional sense, but recent research has shown that some can slowly change their shape or location—about 1–4 mm per day—by rearranging their cells or using contraction-like processes. It’s not movement as we know it, but it helps them adapt to currents or increase their exposure to nutrient flow.
Secrets of Their Survival
Sponges are masters of regeneration. If damaged, they can re-grow lost parts or even reassemble if broken apart. This makes them incredibly resilient. Some sponges have lifespans of thousands of years, and certain deep-sea species may be among the longest-living animals on Earth.
Another fascinating feature is their production of bioactive compounds. Many species produce chemicals that deter predators, prevent infection, or inhibit the growth of nearby competitors. Some of these compounds have been studied for potential use in medicine, including treatments for cancer and viral diseases.
Eco-Friendly Cleaning Tool
Natural sea sponges have long been harvested for use in bathing and cleaning due to their absorbency and durability. Unlike synthetic sponges, they’re biodegradable and sustainably renewable when harvested correctly.
In essence, sea sponges are silent engineers of the sea—purifying water, supporting marine ecosystems, and offering untapped medical potential. Their simplicity hides a world of complexity that continues to captivate scientists and ocean lovers alike.