Characteristics of Phylum Porifera
1.- Multicellular; body an aggregation of several types of cells differentiated for various functions, some of which are organized into incipient tissues of a low level of integration.
2.- Body with pores (ostia), canals, and chambers that form a unique system of water currents on which sponges depend for food and oxygen.
3.- Mostly marine; all aquatic.
4.- Radial symmetry or none.
5.- Outer surface of flat pinacocytes; most interior surfaces lined with flagellated collar cells (choanocytes) that create water currents; a gelatinous protein matrix called mesohyl contains amebocytes of various types and skeletal elements.
6.- Skeletal structure of fibrillar collagen (a protein) and calcareous or siliceous crystalline spicules, often combined with variously modified collagen (spongin).
7.- No organs or true tissues; digestion intracellular; excretion and respiration by diffusion.
8.- Reactions to stimuli apparently local and independent in cellular sponges, but electrical signals in syncytial glass sponges; nervous system probably absent.
9.- All adults sessile and attached to substratum.
10.- Asexual reproduction by buds or gemmules and sexual reproduction by eggs and sperm; free-swimming flagellated larvae in most.
Integrated principles of zoology / Cleveland P. Hickman, Jr. ... [et al.]. – 14th ed. p. cm.