Get Sponge And Cnidarian Review

Cnidarians are a little more complex than sponges. Besides specialized cells, they have tissues and radial symmetry. There are more than 10,000 cnidarian species, see Figure below.

Cnidarians, in the phylum Cnidaria, include organisms such as the jellyfish, corals, and sea anemones. These animals are found in shallow ocean water. You might know that these animals can give you a painful sting if you step on them. That's because cnidarians have stinging cells known as nematocysts.

Cnidarians are radially symmetrical. Sponges have no particular symmetry; they are not radially or bilaterally symmetrical. Cephalization means having a head. For humans and many other animals, our head is the part of the body that has the brain and most of the sensory organs.

Sponges vs Cnidarians One interesting difference between sponges and cnidarians is that sponges lack tissue while cnidarians have tissues but not the organ systems. Sponges and Cnidarians are very primitive acoelomic invertebrates with very simple body structures. Both organisms are found in aquatic ecosystems.

Sponges, ctenophores, placozoans, and cnidarians have key evolutionary significance in that they bracket the time interval during which organized animal tissues were first assembled, fundamental cell types originated (e.g., neurons and myocytes), and developmental patterning mechanisms evolved.

Porifera and Cnidaria are organisms which share similar characteristics with one another. -They are both multicellular, they consist of many cells working together. They are both eukaryotic, they have DNA in the form of chromosomes contained within a distinct nucleus.

Cnidarians lack organs. This means that they do not have respiratory or circulatory systems. Like the cells in sponges, the cells in cnidarians get oxygen directly from the water surrounding them.

Compare the structural differences between Porifera and Cnidaria. Poriferans do not possess true tissues, whereas cnidarians do have tissues. Because of this difference, poriferans do not have a nerve net or muscle cells for locomotion, which cnidarians have.