Anyone know what this guy is?

[Aquattro]

That pic of a hand fed shrimp is because the shrimp has lost it's raptors. Alex is trying to tame it while it's unarmed (pardon the pun)

Mantis can have trouble moulting, as can many shrimp. They need good water and diet.
Other than that, they're not particularly difficult to keep for many years.