- Some kids are just solemn.
- They're still trying to suggest he's got some kind of disorder, though, so...
- Some kids are just solemn.
- "I have my ways, kitten."
- Don't forget the Sea Rhinoceros (usually seen around Sea Bears) the kids befriend.
- It could be possible that she was intended as an Expy, considering that MLP:FIM debuted either before or around that time as this show. If not that, it could be coincidental.
Obviously this generation won't be successful due to lack of mobility on the land. But the breeding program continues...
This version of Earth has an extremely dense atmosphere, which is why the Guppies and many animals appear to be swimming. They are not actually underwater in most scenes.
The Guppies are genetically engineered humans with fish tails, since that's easier than genetically engineering a fish to give it a human head and intelligence. The snails and lobsters have teeth and hair, so they must have had genetic engineering too. Mr. Grouper may be a shapeshifter who can look more human if he wants, or somebody engineered a human to look like a fish just because they can.
The Law of Conservation of Detail sometimes kicks in, such as when we see water poured into a pitcher and it freezes, but doesn't expand like ice is supposed to. The creators didn't worry about how water freezes in a hyper-dense atmosphere. This may also apply when the characters are stuck in a tree or climbing down a ladder. How they would really deal with those in a hyper-dense atmosphere isn't something the creators felt the need to calculate.The idea of the hyper-dense atmosphere seems like a more likely reason for rain, snow and other things we see on the show.
The duplicate Earth with genetically engineered creatures also explains why the creatures are generally not a threat, and speak English, or whatever other language the Guppies are speaking.
We never see or hear about the guppies' parents (with one exception when Molly's sister Mia was born.) The Guppies seem to have relatively good musical skill, which can imply that they acquired this skill somewhere, maybe from their parents. This implies that the kids' parents are in a band and that the Guppies are stage kids.
Mr. Grouper's class is small for a preschool, and he seems to run the whole facility himself, implying the school is private and the guppies are rich.
The guppies wave and interact with the cameramen, not the viewers.
In one episode, the guppies play at a band, and Mr. Grouper introduces them as if they are a household name of some sorts, meaning that the series may exist canonically in the Bubble Guppies universe.