Tube Sponge    Leucosolenia sp.



This weird creature looks like the skeleton of a flea, but it's not even closely related.  It is a sponge, a very primitive animal that has a wide variety of cousins in the Pacific NW.  Sponges range in form from upright tubes to balls and encrusting mats.  This little fellow (around 2 inches long) was found under a float at the Boston Harbor Marina.  It ranges from British Columbia to Southern California.  It differs from other sponges in the numerous small tubes that give it a branching appearance.  It also tends to be whitish in color.


You are probably familiar with large sponges that are used as household tools for cleaning windows and countertops and washing cars.  Those species were harvested from tropical locations until the resource was depleted.  Today most sponges found for sale are artificial.


Sponges are the next step up from single celled organisms because several cell types are cooperating to form a large multicellular structure.  One cell type forms microscopic openings for incoming water and line the walls of the water-carrying canals.  Within the canals are chambers that house other cells with two functions: collars that catch plankton and flagella that move the water through the canals.  The water exits from the sponge through large easily seen openings.  Some cells make a supporting material called a spicule whose chemical composition and shape is so varied that it is used to identify sponges.  Sponges can reproduce through budding where parts of the mass breaks off and grows another individual or through sexual reproduction where there is a fusion of genetic material between two separate individuals.