Dolphin Facts: Habitat, Behavior, Diet – ThoughtCo

Dolphins (Odontoceti) are a group of 44 species of toothed whales or cetaceans. There are dolphins in every ocean on Earth, and there are freshwater species of dolphins that inhabit rivers in South Asian and South American. The largest dolphin species (the orca) grows to more than 30 feet long while the smallest, Hector’s dolphin, is just 4.5 feet in length.

https://www.thoughtco.com/facts-about-dolphins-129800