Question: Is a dolphin a small whale?

Valeria Senigaglia answered on 11 Jun 2012:

Nope,
dolphins and whales have some characteristics in common, for example are both marine mammals so they lactate and give birth to formed and alive babies (called calves).
However they eat in very different ways, in fact dolphins have teeth so they can chew fishes and squids while whales have baleens, these look like a broom made of keratine (the same material as your fingernails). To eat, whales engulf large quantity of water, then they close their mouth and they spit the water out with their tongue. However krill (tiny shrimps) remains entangled in the baleen and constitute the whales’ meal.
they also have very different society, while dolphins usually live in big group, whales are more solitary. this makes sense because big whales don’t need the protection of other whales against predators while small dolphins may gain advantage from being in large group so that they can defend themselves and hunts all together.