Amodel organism is a species that researchers study to better understand certain biological process mollusks and arthropoda are commonly used as model organisms for studying mechanisms of learning and memory , while sponges and jellyfish are not why this?

Both arthropods and mollusks possess cephalization, while sponges and jellyfish do not.

Explanation:

The processes of memory and learning are the functions of the brain. Cephalization refers to the procedure of concentration of sensory composition and development of head in organisms. The sponges and jellyfishes are the radially symmetrical species with no cephalization. The flatworms were the first to possess certain cephalization. The arthropods and mollusks are the species that possess greater extent of cephalization and thus are used as model organisms in order to examine the mechanisms of memory and learning.

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