Catching the crabs can be tricky but it is possible. The blue crab will always turn right and the left crab will always turn left - but only if they are not close to the octopus, fish or sea star. Hope this helps.
Viewing post in Crabs'n'Sticks jam comments
Great job catching both the crabs!
Yes, the crabs can run over the fish and the sea star. They have three goals listed in priority order:
1) Avoid the octopus: Long distance (100 pixels)
2) Avoid the sea star: Short distance (50 pixels)
3) Approach the fish: Short distance (50 pixels)
There is no random component in the crab motion.