There are many dolphins present in the ocean of Ecco's universe. Although some live solitary lives, most live in family units known as pods. Communication is done via clicks and sonar, also known as songs.
Most dolphins are friendly creatures that will aid Ecco throughout his adventures, either by giving him hints or rewarding him for meeting goals such as bringing a fish or winning a race. Some dolphins are aggressive, most notably the Clan.
Bottlenose Dolphins are the main cetacean species in the Ecco games. Ecco and his pod are Bottlenose dolphins. These species are fairly large. Breaching, chasing and playing is common for the species. Bottlenose dolphins occur in Ecco the Dolphin, Ecco Junior, Ecco: The Tides of Time and Ecco: Defender of the Future.
Skyfins are an evolved species of dolphins from the distant future with levitation abilities. They are larger than typical bottlenose dolphins, though resemble them in colouration. Some of them appear to have the ability to time travel at will.
The Outcast are green dolphins that appear in the Dolphin's Nightmare scenario of Ecco: Defender of the Future. They have developed gills which removes the need to surface for air. They are rivals of the Clan.
The Clan are an aggressive pod first seen in Entrapment in Ecco: Defender of the Future. These large half-orca species feature multiple spines and tusks. Most are yellow, green and black. Clan dolphins use crimson markings to identify their rank in the pod. They are rivals of the Outcast.