Did you know that the snail and the squid are related? Even though the snail has a shell and the squid doesn’t, they are related by their characteristics--they are both in the phylum Mollusca, also known as mollusks. Mollusks have some specific characteristics.
Mollusk Characteristics
- Mollusks are invertebrates that lack a true skeleton.
- They have soft bodies with bilateral symmetry. Organisms with bilateral symmetry have a body plan that divides the right and left sides of the organism into mirror images of each other.
- Mollusks have organ systems. They have developed circulatory, digestive, and excretory systems. The circulatory system is open but has a defined heart. Their digestive systems have evolved into very efficient systems for collecting wastes from body fluids and discharging them out of the body.
- Mollusks filter out water pollutants and carry them in their bodies.
Some mollusks creep across the reef very slowly, while others live their lives cemented in place. Mollusks are good indicators of the health of the oceans they live in.
Reflection
Question
Why are mollusks good indicators of their habitat?
Mollusks filter out water pollutants and carry them in their bodies. The more mollusks there are, the healthier the environment will be!
