Animales simples: investigando a los moluscos

The video explains that mollusks are invertebrate animals, including clams, squid, and mussels. Most have a hard outer shell for protection, while some have internal shells or none at all. Mollusks possess a well-developed nervous system with a brain and sensory organs like eyes.

Can you name some mollusks that do not have shells?

What is a characteristic of mollusks' nervous system?