Annelids are considered closely related to mollusks. How are they different?

Question

Julian Aguilar · Accepted Answer

They do not have shells.

Annelids are also known as segmented worms, most commonly exemplified by the earthworm. These organisms have soft bodies with no tough outer protection. Mollusks also have soft bodies, but they are protected by a hard shell made of #CaCO_3#.

Sebastian Alvarado · Answer

undefined Annelids and mollusks are both members of the animal kingdom, but they belong to different phyla. Annelids belong to the phylum Annelida, while mollusks belong to the phylum Mollusca.

Here are some key differences between them:

1. Body Structure: Annelids typically have segmented bodies with repeating units, while mollusks generally have unsegmented bodies.

2. Symmetry: Annelids usually exhibit bilateral symmetry, while mollusks may show bilateral, radial, or asymmetrical symmetry.

3. Body Covering: Annelids have a body covering called a cuticle, while mollusks have a mantle that often secretes a calcium carbonate shell.

4. Appendages: Annelids typically have bristly appendages called setae for locomotion, while mollusks may have various types of appendages such as tentacles or foot for movement.

5. Reproduction: Annelids reproduce sexually, often with separate sexes, while mollusks can reproduce sexually or asexually, and some species are hermaphroditic.

Overall, while annelids and mollusks share some similarities, they have distinct differences in their body structure, symmetry, body covering, appendages, and reproductive methods.