Definition: Actinostomes are a type of animal that lacks a backbone and have a long, flexible skeleton, which allows them to move rapidly and efficiently through their environment. They are characterized by a series of muscles called appendicular muscles that help them crawl, run, or swim. The most prominent features of an actinostome include: 1. Long, flexible skeletons: These animals often have thick, flexible skeletons that allow them to move in all directions with ease. 2. Large brain and spinal cord: Actinostomes are typically larger than other vertebrates such as frogs and mammals. They contain a large, fluid-filled brain and spinal cord, which allows them to sense their environment, receive sensory information from the surrounding world, and communicate with each other through vocalizations and communication. 3. Sensory neurons: Most actinostomes possess multiple sensory neurons that are used for sensing their environment or communicating with other animals. 4. Large eyes: These animals have large, dark eyes that are typically located on the back of their heads. The definition of an actinostome can vary depending on the specific species and evolutionary history of the animal, but generally refers to a type of marine invertebrate that lacks a backbone and has a long, flexible skeleton for movement.

actinostome