∞ generated and posted on 2016.09.02 ∞
Members of animal phylum Porifera, which uniquely among animals digest their food within cells rather than extracellularly.
Sponges are primitive filter-feeding animals. They obtain their nutrients and energy from materials that they phagocytize such as one sees with many protozoa including choanoflagellates.
Unlike even colonial choanoflagellates, however, sponges display cellular differentiation, separate germ cells, juvenile forms (which are responsible, along with sperm cells, for sponge dissemination about environments), and an extracellular matrix consisting in part of the protein collagen.
Unlike other animals, sponges lack what is known as a "tissue grade" of body organization, but instead display only a "cellular grade" of organization. Sponges, that is, possess specialized cells but not specialized groups of cells.
The following video shows the movement of water into and through a complex sponge:
The following video takes us on a plunge into the 'abyss' through the sponge belt(!):