Metroid Database Bestiary

The dominant species of planet SR388, Metroids can suck the life force out of living things. A Metroid will latch onto its prey using its hooked mandible and siphon life force energy. Their internal organs seem to be limited to nucleonic absorption cells and massive energy reservoirs. As energy-based creatures, they will show immediate mass increases upon energy absorption. The only way to shake an attached Metroid off is to enter Morph Ball mode and lay a bomb.

Any Metroid enthusiast should know by now how to kill a Metroid: Ice Beam to freeze it, Missile to kill it. If you don't have the Ice Beam, a Super Missile or a Power Bomb will also suffice, but in the Prime series, Metroids can also be defeated with the Charge Beam.

If a Metroid latches onto Samus, lay some Bombs to free her from its clutches.

Metroids in Prime will grow larger if they latch onto Samus and are removed or if they absorb a large amount of damage. You can also release Metroids from their cages, and they will attack any Space Pirates in the area before turning their attentions on Samus. Apparently, the Pirates had a problem with personnel taunting the Metroids in their holding pens... Metroids will also be destroyed automatically if they somehow exit the room in which they appear, such as by latching onto Samus and then leaving the room.

Longtime Metroid fans have also noted that in all previous games, the only way to defeat a Metroid was by freezing it and shattering it with Missiles or destroying it with Power Bombs. Also, due to the game having a much slower rate of fire for Missiles, it only takes a single Missile to kill a Metroid rather than the usual five. These changes were made to better facilitate the gameplay structure of Metroid Prime, even if they are somewhat inconsistent with traditional Metroid lore, leading some fans to classify them as a particular breed of "Tallon Metroids" mutated by Phazon.

The Space Pirates found Phazon strain Vertigo to be particularly effective on the Metroids. They also noted that Metroids would not feed on any of the synthetic energy they created and would only feed on "active bio-energy sources".