* Streamlined bodies: This helps them move efficiently through water.
* Fins: They both have fins for stability, balance, and maneuvering.
* A dorsal fin: This helps them stay upright in the water.
* A tail fin: This is used for propulsion.
* Cartilaginous skeletons: This makes them lighter and more flexible.
* They are apex predators: They are at the top of the food chain in their respective environments.
However, they are very different animals in terms of their:
* Class: Sharks are fish (Chondrichthyes) and dolphins are mammals (Cetacea).
* Breathing: Sharks breathe through gills and dolphins breathe air with lungs.
* Reproduction: Sharks lay eggs or give birth to live young. Dolphins give birth to live young and nurse them.
* Warm-bloodedness: Dolphins are warm-blooded, while sharks are cold-blooded.
* Body covering: Sharks have scales, while dolphins have smooth skin.
While they share some similar physical features due to convergent evolution (developing similar features due to similar environmental pressures), they are fundamentally different types of animals.