At the end of season one's last episode in Shinryaku! Ika Musume, Ika Musume loses her squid powers, like glowing, tentacle usage, and regeneration, among others. In fact, it seems that the only power she kept was breathing underwater. Why? The anime gave no reason for her powers to go away, nor any reason for them to come back. The trigger was, "someone is in danger", but Takeru threw an inflatable orca at her to no avail, and Sanae managed to glomp Ika without being hurt. Given Ika's notorious selfishness, the best motivator should have been her being in danger, rather than someone else.
Was it ever explained or implied in the manga? Was this anime-only filler? What's the deal with that?