A Piranha inspired robot which was last seen in "AQUATIC RUIN ZONE" in "Sonic 2". It lurks underwater hunting for its next victim. Once they spot Sonic and his friends, nothing will stop their rapid approach and attempt to crush them with its powerful jaw.
— Profile, Sonic the Hedgehog 4: Episode II website
The Chop Chop (ピラーナ Pirāna?, lit. "Piranha") is a reoccurring enemy in the Sonic the Hedgehog series that first appeared in Sonic the Hedgehog 2. It is a piranha-type Badnik created by Dr. Eggman, that hovers underwater sections at high speed while moving his sharp teeth on mouth, making it difficult to dodge.
Chop Chops are similar to Choppers and Mashers, however it does have many alterations on its design. The majority of the upper mechanical body is colored blue while lower body is yellow. Chop Chops have only single dorsal- and anal fin, which are yellow and grey coloring. Each side of Badnik's lower body has a grey motor that keeps Badnik moving. The mouth of Chop Chop has sharp teeth that Badnik keeps chopping during the charge. Each side of mouth's corner has grey bolt, which may indicate an eye.
The appearance of Chop Chop in Sonic the Hedgehog 4: Episode II is slightly different, as the anal fin is replaced with two yellow and white pelvic fins and motors are seen to have turbines as well. Both bolts have sharp eye while the yellow, lower jaw is larger than before.
Sonic the Hedgehog 2
Chop Chops first appear in Sonic the Hedgehog 2, as drifting aimlessly in the waters of the Aquatic Ruin Zone. Once they spot the player, they jet off at high speeds and charge in the players direction with their jaws mashing. These robots can also catch the player unawares by charging backwards too.
With water physics slowing down movement as it is, their fairly fast charge can be hard to avoid, it's best to avoid the waters altogether. However if Chop Chop attacks to the player, it can be destroyed by doing Spin Jump or Spin Attack on right time.
Sonic the Hedgehog Pocket Adventure
Chop Chops make their second appearance in Sonic the Hedgehog Pocket Adventure. These Badniks are seen at Aquatic Relix Zone, which contains similar Badniks and gimmicks. Chop Chops are seen in underwater sections and have their same attack pattern from Sonic the Hedgehog 2.
Sonic the Hedgehog 4: Episode II
Chop Chop makes their reappearance in Sonic the Hedgehog 4: Episode II. The Badnik looks similar to the one in Sonic the Hedgehog 2, though it has a smoother appearance and its eyes are open. Despite that, the attack pattern is almost same, except now it can now turn back and attack behind of the player. It appears in Sylvania Castle Zone and White Park Zone Act 3, being one of few enemies in the game that appear more than one Zone.
Powers and abilities
Chop Chops are dangerous Badniks on underwater sections. As it sees its target, it starts charging into it at high speed, as being underwater makes the victim's maneuvers harder. Chop Chops also move in pairs and sometimes these Badniks lurk at places, where they can not be easy to notice. In Sonic the Hedgehog 4: Episode II, these Badniks are able to turn back and keep attacking on its victim.
In other media
Sonic the Hedgehog Yearbook 1992The large variation of Chop Chop has been appeared in Sonic the Hedgehog Yearbook 1992' story "Big Trouble", which has been created by Robotnik. Sonic and Tails encounter large Badnik underwater of Aquatic Ruin Zone, as they swim fast and leaving it behind easily.
Robotnik tries to smash them by using his Egg Mobile with a hammer extension, as Sonic keeps swimming with Rings being around. However, Robotnik doesn't notice that the Eggmmobile is moving into a large Chop Chop that is starting to open its mouth. Following a collision, Chop Chop and Egg Mobile gets destroyed while Robotnik flies to the pillar.
Adventures of Sonic the Hedgehog
A small number of Chop Chops appear in the pilot episode of Adventures of Sonic the Hedgehog. The Chop Chops, some Mashers and an Octus that chase Sonic as he tries to stop Doctor Robotnik's attempts to drain a lake. The Mashers, Chop Chops and Octus are all defeated when they become entangled in seaweed that whips up behind Sonic as he swims past at high speed.