Zeta Metroid

The Zeta Metroid is the fourth stage of a typical Metroid's life cycle. It morphs from the form of a Gamma Metroid, and does so by shedding the previous form like a butterfly sprouting from its chrysalis. The Zeta Metroid has a very different structure from the previous three forms; it gains a bipedal structure with a tail, and its limbs become clawed. The head is separated from the rest of the body by a short neck. In the place of a Gamma Metroid's beak, the Zeta Metroid grows a leech-like mouth. The Zeta Metroid is much smaller than a Gamma Metroid, and gains quite a bit of maneuverability. It also gains the ability to spit large globs of a damaging fluid of some kind; most likely a form of enzyme that is designed to predigest prey before consumption.

Battle Tactics
The Zeta Metroid is much quicker and more maneuverable than its last form. You can no longer cause damage by firing missiles from underneath; only from the creature's front and behind. The Metroid will spit damaging fluid from its mouth, so firing at it from behind would be more favorable. But this creature is constantly using this strategy against you, and will try and swoop behind you many times. If you're in a wide open space with no ledges, it is easy to get back behind the creature by rolling into the morph ball and going under it as it erratically hovers around in the air. 20 missiles are required to destroy a Zeta Metroid.

Samus Aran encountered Zeta Metroids during her mission to SR388.