Chapter 1——What is a hydrolyzed sponge?

Sponges, phylum Porifera, are the oldest metazoan group still extant on our planet. Their continued survival in vast numbers in Recent seas (and in freshwater habitats) is closely linked to the apparent adaptability of their bauplan to dramatic changes in environmental characteristics and competing biota . Sponges are exclusively aquatic animals, which are fixed on the

substrate and live by drawing in water and filtering microscopic-size food particles from it. Recent research also indicates an ability to take up dissolved organic matter . Sponges have a simple level of organization: there are specialized cells for a variety of life functions, but these are not organized into tissues or organs. All sponges have a 'skin' of T-shaped or flattened cells (called pinacocytes) which covers the outside of the sponge) as well as its internal system of canals, and microscopic chambers.

These chambers have a lining of flagella-bearing cells (choano-cytes) that generate the water currents necessary for the unique filtering activity characteristic to sponges. An exception to this is in the so-called carnivorous sponges, highly adapted deep-sea forms, in which the aquiferous system is non-existent, but which have a sticky outer surface with which small prey animals are captured. The space  between canals and chambers is filled with a collagenous matrix, called the mesohyl,which harbors individual cells, supporting fibers, and inorganic structures of the skeleton.

Sponges grow in distinct shapes and sizes due to the form of the internal mineral and/or organic skeletons secreted by specialized cells. The skeleton may also be supplemented by exogenous materials, such as sand grains. Skeletons, when present, are constructed of discrete siliceous or calcareous elements (spicules) and/or organic collagenous fibers (spongin), and rarely skeletons may be aspicular massive limestone constructions. Depending on the nature and density of these building components, sponge species may variously be soft, compressible, fragile or rock hard in consistency. Sponges come in various shapes and sizes, from flat cushions to elaborate branching or cup-shaped forms, from tiny crusts measured in mm, to giant shapes in meters.Sponges have numerous microscopic openings (the incurrent pores) and one or a few larger vents (the excurrent oscules). The shapes of sponges are variable among different species and genera, but also vary to some extent between individuals of the same species in response to environmental factors such as hydrodynamics, light and turbidity. A great diversity of symbiotic organisms often thrive inside or on the body of a sponge, from microscopic prokaryotes, to macroscopic organisms such as shrimps, polychaetes, hydrozoans and fishes.