From Data Realms Wiki
The planet's native inhabitants, these animals were unlucky enough to get caught in the middle of the resource wars. But that doesn't mean they won't fight back!
The most common native life on the planet. It may not seem the most threatening creature. Crab attacks consist of bumping into you until you die. This isn't the most effective tactic. If you lie down in the sand and let one step on your head it could possibly kill you.
Prior to Build 27, the Crab could be purchased, free. Though unable to use any weapons, Crabs remained very popular with Cortex Commanders (see also "Crab Bomb").
A big crab that defends the nest and protects its smaller brethren. Mega Crab has a thick shell and can take many more bullets than you want to know. It will leap at hostiles and a well-aimed pounce is an instant kill.
At this time Mega Crab is not for sale.
A tiny little shelled, fleshy, one-legged "land mollusk" that just jumps around.
Jumper is also not for sale.