Sponge Classification and Characteristics

Sponge Classification

• Domain: Eukarya
• Kingdom: Animalia
• Phylum: Porifera, meaning "pore bearing"

Sponge Characteristics

• Exhibit asymmetry
• Function as filter feeders
• Lack true tissues
• Possess an internal skeleton made of spicules or collagen fibers

Sponge Body Types

• Ascon Sponge: Least complex structure
• Sycon Sponge: Intermediate complexity
• Leucon Sponge: Most complex, efficient in extracting oxygen and food particles

Calcarea Class

• Comprises marine sponges
• Characterized by small, needle-shaped spicules made of calcium carbonate with 3-4 rays
• Can exhibit ascon, sycon, or leucon body types

Demospongiae Class

• Commonly known as bath sponges or commercial sponges
• Features beautifully colored marine sponges with skeletons made of spongin

Hexactinellida Class

• Comprises marine sponges with six-rayed spicules made of silica
• Can display sycon or leucon body types
• Some taxa inhabit freshwater environments like streams, ponds, and lakes

Spicules

• Structural components that provide support and deter predators; can be made from calcium carbonate or silica

Sponge Structure - Pinacocyte

• Flattened cells that form the outer body wall of the sponge

Sponge Structure - Amoebocyte

• Mobile cells capable of transforming into various cell types, responsible for transporting food within the sponge

Sponge Structure - Porocyte

• Doughnut-shaped cells that facilitate water flow into the radial canals

Sponge Structure - Choanocyte

• Also known as collar cells, they line the radial canals, using flagella to capture food particles, aiding in the sponge's filter-feeding process

Water Flow Through the Sponge

• Water enters through ostia (pores)
• Moves through incurrent canals via porocytes
• Flows into radial canals lined with choanocytes
• Enters the spongocoel (the central chamber)
• Exits through the osculum

Importance of Water Transport in Sponges

• Essential for respiration, nutrient transport, digestion, and excretion
• Allows exchange of oxygen, nutrients, and waste via diffusion and water currents

Asexual Reproduction

• Two main types: fragmentation and budding

Fragmentation

• Sponges break into parts capable of regenerating into new individuals

Bud Formation

• External buds: small sponges detach from the parent
• Internal buds, or gemmules: balls of amoebocytes encased in spongin and spicules that survive harsh conditions

Sexual Reproduction

• Occurs when conditions are favorable
• Choanocytes transform into haploid sperm via meiosis and are released into the water
• Sperm enter a different sponge, fuse with a haploid egg, and develop into ciliated larvae that settle and mature into new sponges

Asexual Reproduction: Gemmule Diagram

• Represents the structural components associated with gemmule formation and resilience

Explore the fascinating world of sponges with this quiz focused on their classification, characteristics, and body types. From the simplest Ascon to the complex Leucon, learn how these unique creatures filter feed and their structural adaptations. Perfect for biology enthusiasts and students alike!