* True Tissues: Poriferans lack true tissues, meaning they don't have specialized groups of cells working together to perform specific functions. They have loosely organized cells with minimal coordination.
* Organs and Organ Systems: They lack organs and organ systems. This means they don't have specialized structures like stomachs, brains, hearts, or any other complex systems for digestion, nervous function, or circulation.
* Symmetry: Sponges are asymmetrical, meaning they have no consistent body plan or shape.
* Movement: While some sponges can move very slowly, they are generally considered sessile, meaning they remain fixed in one place.
* Nervous System: Sponges lack a nervous system, which means they do not have the ability to sense or react to their environment in the same way other animals do.
* Digestive System: Poriferans lack a digestive system. Instead, they rely on intracellular digestion, where individual cells engulf and break down food particles.
* Reproductive System: While sponges can reproduce both sexually and asexually, they lack specialized reproductive organs like gonads.
In summary, poriferans are unique in their simplicity and lack of many features that are considered fundamental to most other animal groups.