1. Body shape: Dolphins have streamlined, fusiform bodies, while sharks have a more streamlined, torpedo-shaped body with a flattened snout.
2. Dorsal fin: Dolphins have a single, prominent dorsal fin, while sharks may have one or more dorsal fins. The dorsal fins of dolphins are typically curved and located in the middle of the back, whereas those of sharks are more triangular and positioned further back.
3. Tail flukes: Dolphins have horizontal, fluke-like tails, while sharks have vertical, lunate tails.
4. Snout: Dolphins have a rounded snout, while sharks have a more pointed snout.
5. Teeth: Dolphins have conical, peg-like teeth designed for catching and holding fish and squid. On the other hand, sharks have rows of sharp, serrated, triangular teeth adapted for cutting through flesh and bone.
6. Skin: Dolphins have smooth skin, while sharks have rougher skin with dermal denticles (tooth-like scales).
7. Blowhole: Dolphins have a single blowhole located on the top of their heads, while sharks have a pair of nostrils located underneath their snout.
These differences in appearance reflect the different evolutionary adaptations and ecological roles of these two groups of marine animals.