Final answer:
Animals display a variety of symmetries, digestive systems, and skeletal structures, with specific adaptations for marine or terrestrial living, alongside bodily segmentation in certain cases, such as in annelids.
Step-by-step explanation:
Jellyfish have radial symmetry, flatworms and roundworms have bilateral symmetry, while organisms like snails and amphioxus show adaptations for land or aquatic living, along with possession of a complete digestive system, skeletons, and in some cases, segmentation The symmetry of an animal is its balanced distribution of duplicate body parts or shapes. Jellyfish possess radial symmetry, allowing an equal division along an axis. Flatworms and roundworms showcase bilateral symmetry, enabling improved mobility. Segmentation, an external and internal division of body sections, is observed in earthworms—members of the Annelida. As for digestive systems, jellyfish present an incomplete gastrovascular cavity, while others like roundworms have a complete digestive tract. Snails have an internal skeleton and are adapted to live on land with a complete gut, while echinoderms, such as sea stars, have calcareous endoskeletons suitable for marine life. Adaptations to live on land can be seen in the muscular foot of snails or the lungs for air breathing in amphioxus and higher animals. A skeleton is absent in jellyfish, while snails have an exoskeleton in the form of a shell, and vertebrates like fish, frogs, reptiles (snakes), birds, and mammals (humans) possess an endoskeleton.