<span>A. endoskeleton
</span>Endoskeleton is not a characteristic of Arthropods that has attributed to their diversity and success. Endoskeleton is defined as inner characteristics of the skeletal feature of an organisms such as bears, humans, fish and etc.
Exoskeleton on the other hand is the trait by which arthropods posses. It is skeletal feature that is described outside or is extrinsic, this is evident as crabs have their skeletons outside of their body.
Explanation:
Worms are invertebrate animals with bilateral symmetry. Worms have a definite anterior (head) end and a posterior (tail) end. The ventral surface of worms and other organisms is the bottom side of the body, often closest to the ground. The dorsal surface is located on the upper part of the body facing the sky. The lateral surfaces are found on the left and right sides of the body. Figure 3.35 compares bilateral symmetry in a whale shark and a swimming plychaete worm. Organs for sensing light, touch, and smell are concentrated in the heads of worms. They can detect the kinds of environment they encounter by moving in the anterior direction
Endoplasmic Reticulum. -- Transport System.
Golgi Apparatus -- Delivery System.
Lysosomes - Intracellular Digestion Centers.
Ribosomes - Sites of Protein Synthesis.
ENERGY RELATED ORGANELLES.
Cytoskeleton - Support System.
Related to Movement.
Nucleus. Cytoplasm . Ribosome . Endoplasmic reticulum . Golgi body . Mitochondria . Lysosome
Cell membrane
the following parts of a cell.
Structure
