In conclusion, dolphins need open space because at sea, dolphins are always on the move, often traveling hundreds, sometimes thousands of miles. Their large brains likely help them to succeed in foraging on widely scattered and temporarily available resources. Dolphins, like some other animals, are essentially complex social mammals that need expansive space to live in. A tank can’t even begin to address these needs…
If you’re going to write a 5 paragraph essay just think of it as writing 3 body paragraphs and an intro and a conclusion. First, introduce what you’re talking about. Then in the body paragraphs talk more in depth about your points you’re making in the essay. Lastly, wrap up your thoughts in the conclusion paragraph.
Go looking for more sources is the option. Writing about something you're confused about is not a good choice. Plagiarism is never the right answer. And picking another research topic is not always a possibility and it's nonsensical to just give up on your original topic.