The Giant Robotic Space Crab, is a boss that appear in 3 star systems, first in Two Forks Are Better Than One (Chapter 2). It also makes two more appearances in the star systems Turn Left At The Space Crab Nebula (Chapter 5) and A Race Against Time (Chapter 9), as an upgraded version. In Chicken Invaders: Cluck of the Dark Side the Crab returns, upgraded to version 2.0, with 2 attacks but actually pretty hard to beat.
For a list of all bosses go here.
Space Crab #1
It has 4 Chicken Catapults that throws chickens at you. It can throw chicks and chickens, chicks move slower than chickens.
Space Crab #2
It's weapons are 4 Instant Lasers.
King Of Crabs
The King has 4 Chicken Catapults and 2 Instant Lasers. It can only throw chickens.
Space Crab v2.0
It's appearance changed, now it is black in color, has red and green eyes and is now harder to kill.
It's weapons are sun-like balls thrower that work pretty much like the Chicken Catapults and a force-field after 12 fireballs thrown. It's force-field also activates after it enters the screen, catching the player off-guard if they don't know the attack pattern.
Its only appearance so far has been in Chicken Invaders: Cluck of the Dark Side.
Although this has not been confirmed, Ben Cooney recently found out that the v2.0 Space Crab might actually a reference to Five Nights at Freddy's 2.
The text entitled "New and Improved" (Like the New and Improved Freddy Fazbear's Pizza on the game's Help Wanted ad) and the Space Crab's endoskeleton-type of appearance are provided as evidence.
They look the same except they have a plant on the bottom of the ship.
It does not throw chickens, but it throws pies.
Its eyes are green and has bells attached to it.