Ecco Jr. is a video game in the Ecco the Dolphin series, released in Summer 1995. It had the controls and basic gameplay of the other two Mega Drive/Genesis titles, but was very much geared towards younger players, lacking the extreme difficulty of Ecco the Dolphin and Ecco: The Tides of Time.
The story was that a younger version of Ecco went to see the Big Blue, completing tasks such as herding seahorses, swimming through rings, and finding lost balls for sea lions along the way. Two other playable characters were introduced: Tara the baby orca (there is also a bottlenose dolphin character named Tara in Ecco: The Tides of Time) and Kitnee the young Atlantic dolphin, who is darker gray than Ecco. They were interchangeable with Ecco and each other at any time; every character had a different voice but not much else was different between them. The game had a password system, though all the passwords were included in the instruction manual, and a "Parent's Menu" that had, among other things, facts about real dolphins.
Source: Wikipedia, [http://en.wikipedia.org/wiki/Ecco_Jr. Ecco Jr. ], available under the CC-BY-SA License.