1. Chidarlans are radially symmetrical whereas flatworms, roundworms mollusks, annelids, and arthropods are bilaterally symmetrical. How does the type of symmetry relate to the lifestyle of each type of animal? 2. Describe the differences between protostomes and deuterostomes.Give examples of animals that are protostomes and those that are deuterostomes. 3. Describe the basic features of lephotrochozoans and ecdysoroans Give an example of each. 4. Many specles of Invertebrates le.g. flatworms roundworms, arthropods) are parasites of other animals. List several advantages, as well as challenges, inherent in a paraslic lifestyle. 5. What makes insects a successful group? d. What distinguishes a chordate from an echinoderm?

## Step 1<br />The type of symmetry in an animal can have a significant impact on its lifestyle. Radial symmetry, as seen in Chidarlans, allows for the animal to interact with its environment from all directions. This is particularly useful for sessile organisms, which are fixed in one place and interact with their environment from all directions. On the other hand, bilateral symmetry, as seen in flatworms, roundworms, mollusks, annelids, and arthropods, allows for streamlined movement in a specific direction. This is advantageous for active, directional movement.<br /><br />## Step 2<br />Protostomes and deuterostomes are two major groups of animals that differ in their embryonic development. Protostomes, such as insects and mollusks, develop the mouth first from the blastopore, while deuterostomes, such as echinoderms and chordates, develop the anus first.<br /><br />## Step 3<br />Lophotrochozoans and Ecdysozoans are two major groups of animals that differ in their body structure and development. Lophotrochozoans, such as mollusks and annelids, have a lophophore, a specialized feeding structure, and undergo direct development. Ecdysozoans, such as insects and crustaceans, undergo ecdysis, or molting, to grow.<br /><br />## Step 4<br />Parasitic lifestyles, such as those seen in flatworms, roundworms, and arthropods, have both advantages and disadvantages. Advantages include a constant food source and protection from predators. However, challenges need to evade the host's immune system and the potential for host death.<br /><br />## Step 5<br />Insects are a successful group due to their small size, which allows for rapid reproduction and dispersal. They also have a hard exoskeleton, which provides protection and support. Additionally, insects have a variety of body forms and functions, which allows them to occupy a wide range of ecological niches.<br /><br />## Step 6<br />Chordates and echinoderms are two major groups of animals that differ in their body structure and development. Chordates, such as vertebrates, have a notochord, a dorsal hollow nerve cord, and pharyngeal slits at some stage of their development. Echinoderms, such as starfish and sea urchins, have a water vascular system and a hard, calcified skin.