Yellow tube sponge

Aplysina aerophoba is a very distinctive type of yellow colored sponge. The body consists of a set of tubular outgrowths, with a smooth yellow surface and holes at the tips, called oscules. When it is exposed to air, it becomes black-green in color, which is why it got the name aerophoba, i.e. afraid of air. It lives in symbiosis with cyanobacteria that inhabit the cells of the outer layer of the sponge. Changeable sulfur is fed by filtration. The flagellate cells cause an inflow of water in the interior cavity of the sponge through tiny pores all over the sponge, called ostia. The water exits through the largest opening, the osculum, which is located at the top of the tubular growths. The flagellated cells of the inner layer of the sponge have cilia with which they hunt microorganisms and suspended particles. It reproduces sexually by gametes (sperm and eggs) and asexually by budding.