1: Parasite (Creature)
#2: Map Station (Research) - There are four of these in the game. Scan them BEFORE you use
them, otherwise there'll be nothing to scan.
#3: Fall of Zebes (Pirate Data) - The only Pirate Data on the Frigate Orpheon, and the only one you can feasibly miss. The name of the room you find it in is "Biohazard Containment".
#4: Parasite Queen (Creature) - The boss of the Frigate. You're encouraged to scan it anyway to find the weak point.
#5: Missile Door Lock (Research) - These are all over the place when you first land on Tallon IV, but they become far more rare later on. Make sure you scan at least one of them, because once you blow them open, they're gone for good.
#6: Hive Mecha (Creature) - This is your first mini-boss on Tallon, specifically the Hive Totem in the Chozo Ruins. It's the thing that makes the
high-pitched noise to release the Ram War Wasps. You DON'T scan the part that turns red. What you need to scan is the part below the water level.
#7: Ram War Wasp (Creature) - In your fight with the Hive Mecha, you should take note of the fact that Wasps you fight are different from standard War Wasps. This is the only place the Rams show up.
#8: Incinerator Drone (Creature) - A mini-boss fought in the Burn Dome.
#9: Barbed War Wasp (Creature) - These Wasps when you fight the Incinerator Drone are also different from the standard War Wasp. Isn't that a pain? Again, this is your only shot.
#10: Flaahgra (Creature) - Like all bosses, there's only one chance.
#11: Flaahgra Tentacle (Creature) - In addition to scanning the main body of Flaahgra, be sure to get the tentacles blocking the holes.
#12: Stalactite (Research) - In Phendrana Drifts and Magmoor Caverns. These ceiling-mounted rock formations cannot be scanned once you drop them to the ground, water, or lava, so be sure to scan one before they're all gone.
#13: Ice Burrower (Creature) - In Phendrana Drifts. Make sure you scan them before getting the Thermal Visor. After that, the place you scan them in will have Sentry Drones instead.
#14: Ice Shriekbat (Creature) - Oddly enough, these guys appear in only one room: Ice Ruins West in Phendrana Drifts, and you must scan them before taking the Thermal Visor, or else they'll disappear from that area.
#15: Ice Parasite (Creature) - They're found in Phendrana Drifts, and the first place you'll see them is the Chozo Ice Temple. After getting the Wave Beam, they disappear from there, but you get another shot at the Frozen Pike later on, after which they'll disappear for good once you get the Gravity Suit.
#16: Thardus (Creature) - Another boss enemy.
#17: Aqua Drone (Creature) - Found in the crashed Frigate Orpheon, in the Biohazard Containment room. After you pass through and enter the Phazon Mines, this enemy will disappear.
#18: Elite Pirate (Creature) - There are only three active ones in the game. The first is in Elite Control, the first time you enter. The second is in
Omega Research after earning Power Bombs. The third is in Dynamo Access after earning the Plasma Beam.
#19: Phazon Elite (Creature) - The only one of these is in Elite Research in the Phazon Mines. Power Bomb the tank to fight it.
#20: Omega Pirate (Creature) - Naturally, you...
#21: Meta Ridley (Creature) - ...only get one...
#22: Metroid Prime (Creature) - ...shot to scan...
#23: (True) Metroid Prime (Creature) - ...these bosses!