You ask and we deliver! And if you have ever had any doubt we are the baddest blog ever, we have carnivorous sponge video! Bolstered by a commenter about the mechansism of flesh eating sponges, I asked Dr. Vacelet to give some more insight into this process.
I was pointed to Vacelet & Duport (2004) Prey capture and digestion in the carnivorous sponge Asbestopluma hypogea (Porifera: Demospongiae). Zoomorphology 123: 179-190). Dr. Vacelet was also kind enough to provide this description.
The prey, mostly small crustaceans and other invertebrates provided with setae or thin appendages, is trapped on the surface of appendages of the sponges, which is lined by tiny hook-like spicules acting as Velcro. Then the cells of the sponge migrate towards the prey, and individually phagocytize and digest fragment of the prey. This is a very unusual phenomenon in pluricellular animals, a unique case in which a non-microscopic prey is digested in the absence of any digestive cavity. This has been investigated in one species, but is likely general for all the carnivorous sponges (family Cladorhizidae), which are deep-sea species usually a few cm high (not really dangerous for a diver…).
But it gets better, there is video (note this requires Real Player and you need to select Une eponge carnivore on the right side)