The animal with no bones is the earthworm.
Understanding Invertebrates
Earthworms are part of a large group of animals called invertebrates. This group is defined by what they lack: a backbone.
- Key Characteristics of Invertebrates:
- No internal skeleton made of bone.
- They often rely on an external skeleton (like an insect's exoskeleton) or a fluid-filled system for support.
Earthworm Anatomy
Earthworms specifically have a soft body structure and no skeletal elements at all, not even a hard external shell. According to the reference, "Earthworms are invertebrates, which means they do not have a backbone. In fact, they don't have any kind of bones." They use their muscular system and body fluid pressure to move and maintain their shape.
Why No Bones?
- Evolutionary Path: Some animals evolved with a bony skeleton (vertebrates), while others evolved without it (invertebrates).
- Movement: Earthworms' lack of bones allows them to move easily through soil.
Summary
To summarize, earthworms are an example of an animal with no bones, as they are invertebrates. They lack any internal or external skeletal structure, relying on other mechanisms for support and movement.
