Although sponges do not have organized tissue, they depend on specialized cells, such as choanocytes, porocytes, amoebocytes, and pinacocytes, for specialized functions within their bodies. Food particles are trapped in mucus produced by the sieve-like collar of the choanocytes and are ingested by phagocytosis. The cnidocyte is a specialized cell for delivering toxins to prey and predators. Identify the life cycle stages of jellies using this video animation game from the New England Aquarium. By the end of this section, you will be able to: The kingdom of animals is informally divided into invertebrate animals, those without a backbone, and vertebrate animals, those with a backbone. But in sponges, cells do not perform any specific duty; they differentiate easily to perform other functions. Sponges release sperm into the water; there they are captured by other sponges just like food particles. Invertebrates include a huge diversity of animals, millions of species in about 32 phyla, which we can just begin to touch on here. Do sponges have tissues and organs? Hence, they possess a cellular level of organization. Type of symmetry? Sponges do have specialized cells and there are cooperation and coordination among the cells, but it is limited.The cells of the body perform their functions more or less independently exhibiting division of labour. Between these two layers is a non-living, jelly-like mesoglea. Poriferans do not possess true tissues, whereas cnidarians do have tissues. But more importantly, if epithelia exist in sponges, then either demosponges have evolved epithelia independently, or epithelia arose with the evolution of the first multicellular animals ( Figure 4 ). Porifera, commonly called sponges, are composed of a few cell types that are not tightly associated into tissues, such as kidneys, gut, or skin. Other animals, including humans, have tissue-level organization because they have tissues with specific functions. Brown tube sponges (Agelas conifera) on Belize reef How long was Margaret Thatcher Prime Minister? Sponges are thought to be the first to branch off the evolutionary tree from the common ancestor of all animals, making them the sister group of all other animals. Cnidarians have specialized cells known as cnidocytes (“stinging cells”) containing organelles called nematocysts. National Geographic article about sponges in the Shape of Life: Was The Humble Sponge Earth's First Animal? All sponges are aquatic and the majority of species are marine. How does sponge ingest food? Sponges do not have organs, but I believe they do have tissues that they are composed of. The body of the simplest sponges takes the shape of a cylinder with a large central cavity, the spongocoel. Cnidarians display two distinct body plans: polyp or “stalk” and medusa or “bell” ([Figure 4]). Gemmules survive hostile environments and can attach to a substrate and grow into a new sponge. Sponges do not have tissues while cnidarians have two tissue layers. Although sponges do not have organized tissue, they depend on specialized cells, such as choanocytes, porocytes, amoebocytes, and pinacocytes, for specialized functions within their bodies. In some cases, the digestive system may extend into the pedalia. Lacking a true digestive system, sponges depend on the intracellular digestive processes of their choanocytes for their energy intake. Comparing Prokaryotic and Eukaryotic Cells, Citric Acid Cycle and Oxidative Phosphorylation, The Light-Dependent Reactions of Photosynthesis, Chapter 6: Reproduction at the Cellular Level, Chapter 7: The Cellular Basis of Inheritance, Biotechnology in Medicine and Agriculture, Chapter 13: Diversity of Microbes, Fungi, and Protists, Chapter 17: The Immune System and Disease, Chapter 18: Animal Reproduction and Development, Chapter 19: Population and Community Ecology, Chapter 21: Conservation and Biodiversity.