1. Lack of Internal Skeleton: In contrast to vertebrates, which have a backbone, soft-bodied animals lack an internal skeleton. They may have an external skeleton, like the shells of mollusks or the exoskeletons of insects, but their bodies are not supported by a rigid internal framework.
2. Diverse Body Shapes: Soft-bodied animals come in various shapes and sizes. Some are symmetrical, meaning their bodies can be divided into mirror images (like jellyfish), while others are asymmetrical (like sea cucumbers). Some are long and worm-like, while others are flat or spherical.
3. Flexible Bodies: Due to the absence of a rigid skeleton, soft-bodied animals have flexible and often muscular bodies. This allows them to move, bend, and contort their bodies in various ways.
4. Diverse Locomotion: Soft-bodied animals employ a wide range of locomotion methods. They can swim, crawl, burrow, glide, or even float. Many aquatic invertebrates use specialized structures like fins, tentacles, or cilia to move through the water.
5. Sensory Structures: Soft-bodied animals have a variety of sensory organs and structures to perceive and respond to their surroundings. They may possess eyes, antennae, chemoreceptors, or light-sensitive cells to gather information about their environment.
6. Diverse Feeding Strategies: Soft-bodied animals exhibit various feeding adaptations. Some are filter feeders, capturing tiny food particles from the water (e.g., sea sponges), while others are predators or scavengers, actively capturing and consuming other animals. Some have specialized mouthparts or feeding appendages to obtain food.
7. Reproduction: Soft-bodied animals can reproduce both sexually and asexually. Many species practice external fertilization, releasing eggs and sperm into the water where fertilization occurs. Others use internal fertilization, with males transferring sperm to females. Some invertebrates reproduce asexually, creating offspring without the involvement of gametes.
8. Habitat and Distribution: Soft-bodied animals occupy diverse habitats, from marine environments to freshwater ecosystems and terrestrial habitats. They are found in various environments, including oceans, lakes, rivers, forests, grasslands, and even deserts.
It's important to note that soft-bodied animals encompass a vast array of species, each with its unique characteristics. The above traits provide a general overview of some common features observed in many soft-bodied animals.