Organisms of which of the following phylum are called sponges ?

The correct answer is Porifera

Explanation:

• Organisms belonging to the phylum Porifera are commonly known as sponges.
• Porifera are simple, multicellular animals that are mostly marine, although a few species live in freshwater.
• Sponges have porous bodies, which is a key characteristic that allows water to circulate through them, facilitating the intake of nutrients and oxygen and the removal of waste products.
• Sponges have a water transport or canal system.
• Choanocytes or collar cells line the spongocoel and the canals.
• Digestion is intracellular.
• The body is supported by a skeleton made up of spicules or spongin fibres.
• Sexes are not separate (hermaphrodite), i.e., eggs and sperms are produced by the same individual.
• Sponges reproduce asexually by fragmentation and sexually by formation of gametes.
• Fertilisation is internal and development is indirect having a larval stage which is morphologically distinct from the adult.
• Example:- Sycon,Spongilla and Euspongia

Other Options:

• Coelenterata: Also known as Cnidaria, this phylum includes organisms like jellyfish, corals, and sea anemones. They have a simple body structure with a single body cavity and specialized cells called cnidocytes that contain stinging organelles.
• Platyhelminthes: This phylum includes flatworms, such as tapeworms and planarians. They are bilaterally symmetrical and have a simple body structure with no body cavity (acoelomates), and many are parasitic.
• Echinodermata: This phylum includes starfish, sea urchins, and sea cucumbers. They have a unique water vascular system and a body plan based on five-part radial symmetry, typically as adults.