Germ Layers: Cnidarians are diploblastic animals, i.e., derived only from two embryonic germ layers, viz., ectoderm and endoderm. How many germ layers does the hydra contain? The epidermis contains a collection of different types of cells. Examine slides of Hydra (phylum Cnidaria, a diploblastic animal) and Lumbricus (the common earthworm, phylum Annelida, a triploblastic animal) and see if you can identify and label the tissue layers. They are diploblastic animals and have a more complex level of organization than Porifera. Body wall (Fig. How many tentacles does your hydra specimen contain? Hermaphrodite. 5. The representatives of Phylum Cnidaria have radial or biradial symmetrical body. Cnidaria also depend on the cilia that line the GVC to move fluid and nutrients throughout the body. Endomesoderm. The inner tissue layer of a cnidarian polyp, larva or medusa. 4.12): ... Cnidaria have no organs (at the tissue level of organization) Term. Which phyla have only two germ layers? The outer tissue layer of a cnidarian polyp, larva or medusa. Inside of Mesoglae (sac) is the GVC. a sac. The body wall of a cnidarian consists of three layers, an outer layer known as the epidermis, a middle layer called the mesoglea, and an inner layer referred to as the gastrodermis. All cnidarians have two tissue layers, with a jelly-like mesoglea between them. Cnidaria have two germ layers and they are the endoderm and ectoderm. 6. 4. Gastrovascular cavity: Definition. Explain the movement of the hydra if live specimens are available. Figure 15.2.4: Cnidarians have two distinct body plans, the (a) medusa and the (b) polyp. A specialized polyp within a hydrozoan colony that forms only medusae or gametes. Acoelomate vs. Coelomate vs. Pseudocoelomate: Many animals have a body cavity. About 99 % cnidarians are marine species and few inhabit in freshwater. Cnidarians are carnivorous animals that possess muscle, nervous, reproductive and digestive tissues. jelly-like layer between 2 germ layers. connects with the outside through the mouth. What type of symmetry is seen in the hydra? Circulatory System: Cnidaria do not have a circulatory system but it is replaced by diffusion across different germ layers, including that of the GVC. Level of Organization: They are the first multicellular animals from evolution point of view which show tissue level of organization. Name the stinging cells present on the tentacles that are unique to cnidarians. Endoderm. In other cnidarians, both a polyp and medusa form exist, and the life cycle alternates between these forms. Can you find the hydra tentacles? % Gonozooid. A germ layer in animal embryos that can give rise to either endoderm or mesoderm. All cnidarians show the presence of two membrane layers in the body that are derived from the endoderm and ectoderm of the embryo. Type of Symmetry: The animals within phylum Cnidaria have Radial symmetry. Term. Muscle tissues (ectodermal) Definition.