Biology Chapter 3: Phylum Porifera

Body Organization and Habitat

• Porifera, or sponges, exhibit a simple body organization characterized by a porous structure with a lack of true tissues and organs.
• Most sponges inhabit marine environments, though some species are found in freshwater.

Reproduction and Gas Exchange

• Sponges typically reproduce both sexually and asexually, through budding or gemmule formation.
• They exchange respiratory gases and nitrogenous wastes through diffusion across their cell membranes.

Structure and Skeleton

• The spongioblasts in sponges are responsible for producing spongin, a fibrous protein that contributes to the sponge's structure.
• The central cavity in a sponge's body is known as the atrium or spongocoel.
• Calcarea sponges have a skeleton made of calcium carbonate spicules, which gives them a rigid structure.

Characteristics of Specific Sponges

• Calcarea sponges are generally small, often not exceeding 10 cm in height.
• Sycon ciliatum sponges exhibit a tubular shape, allowing efficient water flow.
• The unique canal system in Sycon sponges enhances water circulation and feeding efficiency.
• Calcarea sponges are typically found in shallow marine waters.

Classification and Habitat

• Sycon sponges belong to the phylum Porifera.
• Leucosolenia variabilis has thin tube walls that are easily permeated by water, facilitating filtration.
• Commonly, Leucosolenia variabilis is found in marine habitats, often on rocky substrates.

Unique Features of Other Sponge Classes

• Hexactinellida spicules are characterized by silica content and are hexaxon in structure.
• The Venus’ flower basket has the primary function of providing structural support and habitat for small sea creatures.

Importance to Humans and Environmental Indicators

• Leucosolenia has ecological significance, aiding nutrient cycling and serving as a food source for other marine life.
• Hexactinellida sponges are commonly referred to as glass sponges due to their transparent, glass-like appearance.
• The presence of freshwater sponges, such as those in the genus Spongilla, indicates good water quality.

Feeding and Class Information

• Sponges primarily feed through filter feeding, trapping food particles from water.
• Spongilla lacustris belongs to the genus Spongilla, the class Demospongiae, and the order Spongillida.
• The division of Spongilla lacustris is Porifera, indicating its classification as a sponge.

Notable Sponge Types and Functions

• The cylindrical skeleton of the Glass Rope Sponge primarily comprises silica, providing unique structural properties.
• Notably, Glass Rope Sponge reefs serve as important ecosystems and habitats for marine life.
• In Japan, the species commonly used as a wedding gift is Euplectella aspergillum.
• The class Demospongiae represents about 90% of all living sponge species.
• Crustaceans primarily feed on detritus and microorganisms that are filtered out by sponges like Euplectella aspergillum.