No. It doesn’t have the Latin ending -us, but actually ends with pus (fom the Greek word for foot). From the Greek origin, the plural would be octopodes. Octopuses is more usual.
The modern English representation of the classically correct Greek plural (had the word been so used in ancient Athens) would be octopodes. The common plural octopi (1817) regards the -us in this word as the Latin noun ending that takes -i in plural. As with many modern scientific creature-names, it was coined in Modern Latin from Greek elements, so it might be allowed to partake of Latin grammar in forming the plural. But probably the best policy for common words is to follow the grammar of the living language using them, and octopuses goes best in plain English (unless one wishes also to sanction diplodoci for the dinosaurs).
Isn’t it octopi?
No. It doesn’t have the Latin ending -us, but actually ends with pus (fom the Greek word for foot). From the Greek origin, the plural would be octopodes. Octopuses is more usual.
Merriam Webster answered this https://youtu.be/s166nC_hiZ0
Both are acceptable, I’ve read.
https://www.etymonline.com/word/octopus