Well, the key thing to remember is that both craynarbians and graspers are evolutionary offshoots of humanity in the far future.
In the Jackelian universe, at least on Earth, non-human races tend to fall into three categories… naturally evolved offshoots of base human, the result of genetic engineering in the distant past, or alien imports from when Earth still had a space faring culture.
Craynarbians are human-like, but with much of their skin overgrown with crab-like carapace natural armour to protect them from a very harsh natural environment. Think a kind of organic Imperial Stormtrooper, if you're a StarWars fan. They stand six foot tall and their normal human arms and hands (their manipulator arms) have been added to with two extra weapon arms, one a bony club arm, and the other a razored bone-like slicing arm.
Graspers are a branch of humanity that retreated underground during the ice age. They're more or less the same us, but stand about five feet tall, with a variety of natural fur coverings in a range of colours. Their eyes are slightly larger than base human and their skin more leathery.
Hope that’s useful, commodore.