Sponges…weird - in a good way.
- Unifying Characteristics
- Predominantly marine except for two freshwater families
- Metazoan, with loosely aggregated cells
- Adults sessile, commonly encrusting.
- Asymmetrical or radially symmetrical.
- Body permeated with pores, canals, and chambers through which water current flows
- Internal cavities are, at least partially, lined with flagellated cells (choanocytes)
- Possess an internal skeleton of spicules and/or organic fibers.
- A nervous system is absent.
- Possess high regenerative powers.
- Exhibit cellular differentiation, but no tissue layers
- 3 cell layers
epidermis - outer layer
mesenchyme - middle layer
endodermis - inner layer
- Canal systems extend surface area of sponge
- asconoid, syconoid, leuconoid
- Skeletal systems - all sponges possess spicules
- spongin - fibrous, similar to collagen
- calcium carbonate
- Porifera Classification
- Class Calcarea
- calcareous spicules
- asconoid and syconoid canal systems
- Class Hexactinellida - glass sponges
- silicaceous spicules (6-rayed)
- syncold and leuconoid canal systems
Venus flower basket (Euplectella)
- Class Demospongiae
- silicon or spongin spicules, or both
- (spicules never six-rayed)
- all leuconoid
Spongia; bath and basket