Ocean sponges are fascinating multi-cellular animals that don’t walk or swim. They eat by filter-feeding, straining the water around them to capture organic debris particles and microscopic life forms.
How powerful are their filters? How strong is their current for capturing food? With the help of some non-toxic Fluorescein dye, we can see how highly effective ocean sponges are as filters of ocean water. Watch this incredible demonstration in Jonathan Bird’s Blue World: Sponges, which also includes some sponge history and details on sponge anatomy. From Oceanic Research:
The scientific term for sponges is Porifera which literally means “pore-bearing.” A sponge is covered with tiny pores, called ostia, which lead internally to a system of canals and eventually out to one or more larger holes, called oscula. Within the canals of the sponge, chambers are lined with specialized cells called choanocytes, or collar cells. The collar cells have a sticky, funnel shaped collar and a hairlike whip, called a flagellum. The collar cells serve two purposes. First, they beat their flagella back and forth to force water through the sponge. The water brings in nutrients and oxygen, while it carries out waste and carbon dioxide. Second, the sticky collars of the collar cells pick up tiny bits of food brought in with the water. Another type of cell, called an amebocyte, takes the food to other cells within the sponge.
Ocean sponges are just one kind of filter feeder. Oysters are also vital water filters within our marine ecosystems. This Chesapeake Bay Foundation time lapse video demonstrates their essential filtration capabilities:Here’s another excellent example on this site: Sea cucumbers are underwater vacuum cleaners (also known as “the sea cucumber pooping video”).
One more must-see video: Slow Life: Incredible macro video of fluorescing corals and sponges.