What are the similarities between these animals: Shark, dolphin and seal. Where did it come from?

in the shape of the body (elongated shape, the presence of fins, etc.)
it arose in connection with the aquatic lifestyle (sharks are primary aquatic organisms, dolphins and seals are secondary aquatic organisms)



One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.