In order to get this achievement, you'll need to get to the seventh milestone for Planetary Zoology. This basically means you need to scan all of the fauna on a planet.This is actually a lot easier than you'd expect - there's a trick (or "legit" exploit) to getting this achievement.
One way to complete a planet's fauna without running around spending hours looking around
is to find a planet that already has all of the fauna scanned and uploaded by someone else. The easiest and quickest way to do this is to do the weekly community event. Hundreds or thousands of players will flock to the system for the event, and all of the fauna will quickly be scanned. So all you have to do is talk to Specialist Polo at the Anomaly to start the community mission, which will lead you to a portal that you will automatically be able to use no matter how far along you are, and go through it.
Once at the new planet, hit the pause button, go to the fauna section of that planet's discoveries, and you just need to hold
to "upload" all discoveries (even though someone else completed them, you'll be able to do that), then go to the silver paw print in the upper right hand corner, and hold
. This will finalize the upload, and you'll get credit for scanning all the fauna on the planet, even though technically someone else already discovered it all. If someone else has already discovered all of the fauna on the planet, that's literally all that you need to do. Then, jump in your ship and fly to the next planet, and repeat. Once you get credit for "discovering" all of the fauna on all those planets, another community event will come along in a week or so, and you can do it again. Once you hit the seventh milestone, you get this achievement.
Another option is to join someone else's game, where you will be brought to their system, and if you're lucky, they will have already discovered all the fauna on some of the planets, so you can just do what you did above. Unfortunately, it's a matter of luck in this case, obviously there are no guarantees that they will have found all of the fauna - however they may have a good head start, and you have the option of trying to find the remaining fauna.