Porifera

Porifera (also known as sponges) are a group of simple, multicellular, non-mobile organisms that are classified within the phylum Porifera. They are the simplest form of multicellular organisms and are characterized by their ability to filter feed by drawing water in through their porous bodies and extracting nutrients.

Anatomy

Sponges have a unique anatomy, lacking the complex organ systems found in most other animals. Their bodies are composed of a soft, porous, gelatinous substance that is covered by a thin layer of cells. The interior of a sponge is lined with specialized cells called choanocytes or "collar cells", which have a ring of tentacles surrounding a single flagellum. These cells are responsible for generating a current of water through the sponge's body, allowing it to filter feed.

Reproduction

Sponges reproduce both sexually and asexually. In sexual reproduction, sponges produce eggs and sperm, and the sperm is often carried to other sponges by the current of water flowing through their bodies. In asexual reproduction, a piece of the sponge's body, called a bud, grows out and eventually detaches to become a new individual.

Ecology

Sponges play a significant role in marine ecosystems. They serve as habitat for a variety of organisms and are important in nutrient cycling. Many species of sponges are also symbiotic, hosting photosynthetic microorganisms within their bodies that provide them with nutrients.

Classification

The phylum Porifera is divided into three main classes: Demospongiae, Hexactinellida, and Calcarea. These classes are distinguished by the types of spicules (skeletal elements) present in the sponges' bodies.

See also

• Metazoa
• Animal

External links

• Poriferan at Britannica

Porifera Resources
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