Phylum Porefera:

Porefera(Latin, porus=pore + fera=to bear), also known as sponges, is a diverse group of aquatic animals that are characterized by their porous structure. They belong to the kingdom Animalia and are the simplest of all multicellular animals. This phylum consists of more than 10,000 species and are found in oceans, rivers, and freshwater habitats.

Introduction of Sponges:

Sponges are the most primitive type of multicellular animal and have been in existence for over 700 million years. They are known for their ability to filter large amounts of water, making them critical to the aquatic environment. Sponges are also used in various applications, such as cosmetics and medical treatments, due to their unique properties.

Cell Types:

Sponges have three main cell types: pinacocytes, porocytes, and mesenchyme cells.

• Pinacocytes:

Pinacocytes are the outermost cells of the sponge and are responsible for forming the outer layer of the sponge body.

• Porocytes:

Porocytes are the cells that form the water-carrying channels within the sponge.

• Mesenchyme cells:

Mesenchyme cells are the cells that make up the innermost layer of the sponge and are responsible for supporting the structure of the sponge and for transporting nutrients and waste.

Size:

Sponges can be found in a range of sizes, from tiny individuals less than a millimeter in length to larger species that can grow up to 1.5 meters.

Characteristics of Phylum Porefera:

Here some of the general Characteristics of Phylum Porifera:

• Spherical or irregular shape:

Sponges are usually circular or irregularly shaped, with a porous body structure.

• Asymmetrical Body Plan:

Sponges lack a true head, tail or distinct left and right sides, making them asymmetrical in structure.

• Poriferous Structure:

The body of sponges is characterized by numerous small pores called ostia, which allow water to flow in and out of the sponge.

• Absence of true tissues and organs:

Sponges are simple multicellular organisms, lacking true tissues and organs like those found in more complex organisms.

• Filter-feeding habit:

Sponges feed by filtering water that flows through their body, trapping small particles of food in specialized cells called choanocytes. This filter-feeding habit is the basis of their survival

Structure of Cell Wall and Skeleton:

Sponges have a porous body structure that is composed of a mesh-like network of cells and fibers.

The cell wall of sponges is composed of a tough, flexible material called spongin, which helps to support the structure of the sponge.

Some species of sponges also have a rigid, mineralized skeleton made of silica or calcium carbonate.

Movement:

Sponges are sessile and do not move once they have attached to a solid surface. However, they are capable of limited movement through the contraction and expansion of their body, which helps them to regulate water flow and obtain food.

Role of Water Currents:

Sponges are dependent on water currents for their survival, as they use these currents to filter food and oxygen from the water.

The water-carrying channels within the sponge also help to circulate water, which helps to remove waste and distribute nutrients throughout the sponge.

Body Forms:

Sponges can be divided into three main body forms: ascon, sycon, and leucon.

• Ascon sponges have a simple body plan, with a single layer of pinacocytes surrounding a central cavity.

• Sycon sponges have a more complex body plan, with multiple layers of pinacocytes and a more elaborate system of water-carrying channels.

• Leucon sponges have an even more complex body plan, with a labyrinthine network of water-carrying channels and numerous chambers.

Maintenance Functions:

Sponges play an important role in maintaining the health of the aquatic environment. They filter large volumes of water, removing debris, excess nutrients, and other pollutants. This helps to maintain water quality and support the growth of other aquatic organisms.

• Filtration in Choanocytes:

Choanocytes are specialized cells found in the sponge body that are responsible for filtering water and capturing small particles such as bacteria and organic matter. They have a unique flagellum, which creates a water current that draws water into the sponge, and a collar of microvilli, which form a filter to trap particles.

In filtration, water enters the sponge through small openings, or ostia, and moves through the sponge body, encountering choanocytes along the way. The beating of the flagellum creates a flow of water that draws water and particles into the collar of microvilli, where the particles are trapped. The choanocytes then move the particles to the sponge's central cavity, where they are engulfed and digested by other cells within the sponge.

Filtration by choanocytes plays an important role in the survival of sponges, as it provides the cells with the nutrients they need to grow and reproduce. It also helps maintain the water quality within the sponge, as the choanocytes are able to remove particles that might otherwise clog the sponge's water-flow system or be harmful to the cells.

Nervous System in Sponges:

Sponges do not have a traditional nervous system like that found in other animals. Instead, they rely on a simple network of specialized cells called collar cells or choanocytes, which are responsible for filtering water and capturing food particles. These cells are capable of sensing changes in water flow and the presence of food particles, and they can respond by changing their behavior to capture the food.

However, some species of sponges have been found to have specialized cells called spicules that can respond to touch and other stimuli.

These spicules have been shown to have the ability to move and change shape in response to stimulation, suggesting that they may play a role in the simple sensory system of some sponges.

Overall, the lack of a complex nervous system in sponges limits their ability to respond to environmental stimuli and to coordinate their activities in a sophisticated manner.

Nevertheless, sponges have been able to survive and thrive for millions of years in a variety of environments, using their simple but effective sensory system and their ability to filter water and capture food to ensure their survival.

Life Cycle──Reproduction:

Sponges are primitive, aquatic animals that reproduce both sexually and asexually. They have a unique mode of reproduction that allows them to colonize new habitats and ensure the survival of their species.

There are two main types of reproduction in sponges: sexual and asexual.

Sexual Reproduction:

Sexual reproduction in sponges involves the production of gametes, which are specialized cells that are involved in the formation of offspring.

In most sponges, both male and female gametes are produced in the same individual, and they are released into the water column where they can fertilize each other.

Fertilization occurs when a male gamete fertilizes a female gamete, forming a zygote. The zygote then develops into a larvae, which settles on a suitable surface and develops into a new sponge individual.

Asexual Reproduction:

Asexual reproduction in sponges involves the production of offspring without the involvement of gametes.

There are several methods of asexual reproduction in sponges, including fragmentation, budding, and gemmulation.

• Fragmentation:

Fragmentation involves the breaking of an individual sponge into smaller pieces, which then develop into new sponge individuals. This method of reproduction is common in many species of sponges and allows them to quickly colonize new habitats.

• Budding:

Budding involves the development of a small, rounded outgrowth on the surface of an individual sponge. This outgrowth eventually detaches from the parent sponge and develops into a new individual.

• Gemmulation:

Gemmulation is a type of asexual reproduction that occurs in some species of sponges. It involves the formation of small, protective structures called gemmules within the sponge tissue.

These gemmules contain cells that are capable of developing into new sponge individuals, allowing the species to survive unfavorable environmental conditions.

In fact, sponges are capable of reproducing both sexually and asexually, allowing them to colonize new habitats and ensure the survival of their species. The unique modes of reproduction in sponges have allowed them to adapt to a wide range of environmental conditions and to persist as a diverse and abundant group of animals.

Conclusion:

In short,Phylum Poriferae is a taxonomic classification that encompasses a diverse group of organisms known as sponges. They are primitive, sessile (non-moving) animals that lack true tissues and organs, but have a highly porous and spongy structure made of collagen fibers and specialized cells called "choanocytes". Sponges are found in a variety of aquatic environments, including oceans, lakes, and rivers.

They feed by filtering microscopic food particles from the water that passes through their porous body structure. Sponges play an important role in marine ecosystems, serving as habitats for other organisms and helping to regulate water quality by filtering out excess nutrients and pollutants. Despite their simple structure, sponges are incredibly diverse, with over 10,000 species known to exist, each with unique characteristics and adaptations to their environment.

Phylum Porifera: Introduction and Characteristics

Phylum Porefera:

Introduction of Sponges: