Introduction

Porifera, also known as sponges, are a diverse group of aquatic animals that belong to the phylum Porifera. They are characterized by their porous body structure and the presence of specialized cells called choanocytes. Sponges are sessile, filter-feeding organisms that can be found in a wide variety of aquatic habitats. The classification of Porifera is divided into three main classes: Calcarea, Hexactinellida and Demospongiae.

Calcarea

• The class Calcarea is characterized by the presence of spicules made of calcium carbonate.
• Spicules are small, needle-like or star-shaped structures that provide support and protection for the sponge.
• Calcareans are typically found in shallow, marine environments and have a skeleton made of spicules.
• Example of Calcarea sponges are Sycon ciliatum, Leucosolenia complicata, and Leucosolenia botryoides

Hexactinellida

• The class Hexactinellida, also known as glass sponges, are characterized by the presence of spicules made of silica.
• These spicules are typically six-rayed, giving the class its name.
• Hexactinellids are found in deeper marine environments and have a skeleton made of spicules.
• They have a complex body organization, some of them have a central canal system, and others have a radial canal system.
• Examples of Hexactinellida sponges are Euplectella aspergillum, Monorhaphis chuni, and Rossella racovitzae

Demospongiae

• The class Demospongiae is the most diverse class of Porifera and includes about 90% of all known sponge species.
• They are characterized by the presence of spicules made of spongin, a protein-based substance, and/or silica.
• Demosponges are found in a wide variety of aquatic habitats and have a skeleton made of spicules and/or spongin.
• They have a relatively simple body organization, most of them have a single-layered choanoderm, and no centralized canal system.
• Examples of Demospongiae sponges are Spongilla lacustris, Hippospongia communis, and Spongia officinalis

Conclusion

The classification of Porifera is based on the type of spicules present in the sponge and the body organization, Calcarea have calcium carbonate spicules, Hexactinellida have siliceous spicules, and Demospongiae have spongin spicules. Each class of Porifera is adapted to different environments and way of life. The study of sponges and their classification can give us more insight into the evolution and diversity of life on Earth.