|This article is written from a Real World point of view.|
- "To go on was to lead my team – my friends further into the unknown. And from what we'd just seen on the Japanese carrier, there was a good chance the unknown was seriously weird. And probably very dangerous. Or go back. Turn around. Forget the search for the Sea Blade. Leave it to chance whether Visser Three ever found the Pemalite ship. Stole its secrets. Used those secrets to further the Yeerk invasion of Earth. The visser. The Abomination responsible for the sickening recent torture and murders of Hahn and forty-nine other innocent Hork-Bajir."
The Mutation, published in November 1999 and written by Erica Bobone based on an outline by K.A. Applegate, is the thirty-sixth book in the Animorphs series. It is the twelfth book narrated by Jake and the eighth book with Jake as the sole narrator.
Visser Three is still trying to find a way to reach the Pemalite ship. The ship that was hidden thousands of feet below the ocean's surface. A ship containing technology so advanced that it is superior to anything even the Andalites have built. And this time, the visser plans to find the ship so he can use the power to complete Earth's invasion.
Jake, the other Animorphs, and Ax acquire additional deep-sea morphs in order to stop the visser's plan. But while trying to destroy the Yeerk ship, the kids make a startling discovery: an underwater civilization. Have the kids discovered Atlantis...or is it just another trap?
- Hahn Tunad (Only Appearance) (Death)
- Elfangor-Sirinial-Shamtul (Mentioned Only)
- Eva (Mentioned Only)
- Tom (Mentioned Only)
- Walter (Mentioned Only)
- Michelle (Mentioned Only)
- Pemalites (Mentioned Only)
- Peter (Mentioned Only)
- Nora Robbinette (Mentioned Only)
- Euclid (Mentioned Only)
- Wildlife Rehabilitation Clinic
- Nartec City
- Sea Blade
- Abandoned Construction Site (Mentioned Only)
- Hork-Bajir Valley (Mentioned Only)
- The Gardens (Mentioned Only)
- Yeerk pool (Mentioned Only)
- Dracon beams
- Sea Blade
- Elfangor's fighter (Mentioned Only)
- Pemalite ship (Mentioned Only)
- Blade ship (Mentioned Only)
- The Animorphs discover an underwater civilization known as the Nartec, which are revealed to be amphibious, mutated humans who dissect and kill humans and wish to reverse engineer human technology to conquer the surface civilizations.
- The Animorphs work with Visser Three for the first time.
- Jake, as the leader of the 'Andalite bandits', uses thought-speak to communicate with Visser Three for the first time.
- Jake and Cassie's relationship is conveyed, with the pair holding one another during Hahn's death and Jake later referring to Cassie as his girlfriend for the first time.
- Tobias and Rachel's relationship is briefly shown, with Rachel hugging Tobias after he frees them and Tobias responding that he was worried about her as well.
|Morpher||Morphs acquired||Morphs used|
|Jake||Orca (Swoosh)||Peregrine Falcon, Orca (Swoosh), Hammerhead Shark, Great Horned Owl, Siberian Tiger|
|Rachel||Orca (Swoosh)||Orca, Sperm Whale (Swoosh), Hammerhead Shark, Great Horned Owl, Grizzly Bear|
|Tobias||Orca (Swoosh), Nartec||Orca (Swoosh), Sperm Whale, Hammerhead Shark, Nartec|
|Cassie||Orca (Swoosh)||Orca (Swoosh), Hammerhead Shark, Great Horned Owl, Wolf|
|Marco||Orca (Swoosh)||Osprey, Orca (Swoosh), Hammerhead Shark, Great Horned Owl, Silverback Gorilla (Big Jim)|
|Ax||Orca (Swoosh)||Orca (Swoosh), Hammerhead Shark, Great Horned Owl|
|Visser Three||--||Luminar, Unnamed Giant Squid-like creature|
- The cover quote is, "You won't even get the chance to change your mind...."
- The inside cover quote is, "The Animorphs have a whale of a problem...."
- This is the eighth book in which all the Animorphs acquire the same new morph.
- This marks the fourth time that the Chee pose as the Animorphs while they are on a mission.
- ANIBASE: One of the downfalls of writing a series is the need to keep coming up with new idea after new idea. "Frankly", K.A. Applegate says of this book, "I think I was getting a little desperate for ideas!" Here's what she had to say about what might have been the influence for this book: "I used to write Little Mermaid books for Disney, so maybe this was my anti-Ariel fantasy."
- ANIBASE: Queen Soco is the leader of the mutated Nartec. She cares only about her people, and has a grand, never-to-be-fulfilled goal of one day overtaking the world of Surface-Dwellers. Naca was a Nartec guard assigned to the Animorphs.
- On p7, Hahn is on a metal operating table, but on p9 he's on bales of hay.
- Toby Hamee informs Jake and Cassie that Visser Three is searching for the Pemalite ship after his efforts were thwarted by the Drode, despite the fact that the Drode made himself known to only the Animorphs during The Exposed; had the Visser been able to see and hear the Drode, he would have heard the Drode refer to the 'Andalite bandits' as humans.
- On p12, Jake states that it is the next day, but immediately adds that it's only been hours since Hahn's death (the previous chapter).
- Ax informs them that Visser Three has constructed a new vessel known as the Sea Blade for the sole purpose of diving deep to locate the Pemalite ship, despite the fact that Bug fighters were able to do so in The Exposed.
- Ax also states that the Chee have informed him of the Pemalite ship's true location and that it is deep, but not too deep, citing that it is possible for humans and Yeerks to find it. However, in The Exposed, the Pemalite ship was located so deep that the Animorphs had to morph giant squids to reach it, and at the end of that book, Erek King moved it even deeper to a depth only an android could reach.
- On p21, Jake is the first to notice the hologram, notifying Marco. However, on the same page, Jake remarks that Marco was the one to notice it.
- When Jake notices that an orca has been split in two, he calls out to his team to check up on them, receiving assurances from Tobias, Cassie, Ax and Marco. Jake is relieved that his friends are not dead, despite the fact that Rachel did not respond back nor did Jake or any of the Animorphs remark on Rachel's lack of reply.
- Jake refers to his regular self as his 'human morph' on p63.
- Marco's line begins with a thought-speak tag but ends with a quotation mark on p68.
- On p86, Queen Soco speaks various languages in an attempt to communicate with the Animorphs, while Marco and Rachel mutter in English. After Jake asks her if she can speak English, she replies that she can, after which Marco mutters that she must be a queen. Queen Soco then tells him that her hearing is quite good and that she is indeed a queen. If her hearing was good enough for her to hear the Animorphs whispering, then she would have heard them speaking in English to begin with.
- Ax says On my commnad on p136, when it should be 'command'.
- A thought-speak sign is in the wrong direction when Jake asks about the Visser on p140.