Phylum Porifera Flashcards

Phylum Porifera

• Considered simplest metazoans, characterized by loose cell aggregation and minimal tissue organization.
• Exhibit cellular level of organization, with a division of labor among cells.
• Lack organs and organ systems, as well as structures like a mouth or digestive tract.
• Not classified as diploblastic or triploblastic; feature rudimentary nervous integration.

Chief Characteristics of Sponges

• Defined by pores and canal systems facilitating water flow.
• Choanocytes, flagellated feeding cells, line cavities to create water currents.
• Possess an internal cavity known as the spongocoel, which opens to the outside via the osculum.
• Internal skeletons made of spicules or organic fibers like spongin.

Spongocoel

• Central cavity of the sponge that operates as a chamber for water circulation.

Osculum

• The opening at the terminal end of the sponge, functioning similarly to a mouth, allowing water to exit.

Spicules

• Microscopic skeletal elements made of calcium carbonate or silica, contributing to sponge structure and protection.

Choanocytes

• Specialized cells that line the interior cavities and are responsible for creating water currents, which aids in feeding and respiration.

Grantia

• A genus of calcareous marine sponges within the phylum Porifera.
• Colonial, benthic, and sessile filter feeders, typically asymmetrical in shape.
• Sometimes referred to as Scypha in older literature.

Structure of Grantia (Sycon)

• Specific structural adaptations that include a syconoid body plan, allowing for greater surface area and efficiency in water filtration.

Radial Canal

• Canals lined with flagellated cells, closed at one end and opening into the central cavity.
• Does not have direct connection to the external environment, serving as a passageway for water.

Incurrent Canals

• External spaces between enclosed canals, leading into the sponge while ending blindly at the inner end.

Dermal Ostium

• Minute openings on the sponge surface that provide access to the incurrent canals, facilitating water intake.

Spongin Fiber

• Type of collagen protein forming the fibrous skeleton of many sponges, secreted by spongioblasts.
• Provides flexibility and is characteristic of members in the class Demospongiae.

Glass Sponge

• Specialized sponges known for their silica spicules, distinguishing them from other sponge types.