.ref=== Sponges ===[[File:Callyspongia sp. (Tube sponge).jpg|thumb|Tube sponges attracting small [[reef fish]]]]
[[File:Phoeniconaias minor 01.jpg|thumb|The bill of this [[lesser flamingo]] is well adapted to bottom scooping]]
[[File:Pterodaustro BW.jpg|thumb| The pink coloring of this Pterodaustro is hypothetical, but is based on ecological similarities to flamingoes]]
Sponges have no true [[circulatory system]]; instead, they create a water current which is used for circulation. Dissolved gases are brought to cells and enter the cells via simple [[diffusion]]. [[Metabolic waste]]s are also transferred to the water through diffusion. Sponges pump remarkable amounts of water. Leuconia, for example, is a small leuconoid sponge about 10 cm tall and 1 cm in diameter. It is estimated that water enters through more than 80,000 incurrent canals at a speed of 6 cm per minute. However, because Leuconia has more than 2 million flagellated chambers whose combined diameter is much greater than that of the canals, water flow through chambers slows to 3.6 cm per hour.ref Such a flow rate allows easy food capture by the collar cells. All water is expelled through a single [[osculum]] at a velocity of about 8.5 cm/second: a jet force capable of carrying waste products some distance away from the sponge.