Final answer:
Sponges lack true tissues, which are a characteristic feature of non-sponge animals; they have specialized cells instead and are filter feeders without organized tissues or organs.
Step-by-step explanation:
One major feature that distinguishes non-sponge animals from sponges (Phylum Porifera) is that sponges lack true tissues. In contrast to other animals, which have organs and organized tissues, sponges have specialized cells that perform different functions but do not form true tissue layers. These cells facilitate processes like filtering water for food and gas exchange, making sponges efficient filter feeders. While other animals have complex organ systems and often show some form of body symmetry, sponges have a more simplistic body plan with no true symmetry and no nervous, digestive, or circulatory systems. They are mostly marine invertebrates and have an endoskeleton made up of spicules and spongin fibers.