There are crabs all over on Poptropica, so you have to specify an island.
Time Tangled Island - on this older island, clicking the crab makes him explode
Big Nate Island - it is a lobster, not a crab, that you recover by swapping the old photo for the diving suit and diving at the lighthouse. The lobster can turn the lighthouse light.
Steamworks Island - get the robot crab by climbing to the Living Quarters and jumping on top of him. Use the key to enter Sully's paraphernalia. Once you have the robot Sprocket, you can use him to drop the robot crab on the hot hatch, which will cool it down.
Wimpy Boardwalk - the crab is used to recover the $20 bill at the end of the quest. Once you have the toy helicopter, use the slippery lotion to free Rowley from the fun house slide, and you get some Fish Sticks. Use the sticks to bait the hook on the copter and catch the crab at the ocean.
(see related questions below)
it is in the museum after the story
hygc
You don't need to use anything
On Poptropica, Steamworks island you are using the robot crab to cool down the bell. Once you have cooled the bell down you can touch it without being burned.
Use the helicopter with the crab on it to scare them.
you put the fish stick on the toy helicopter and use it to get the crab
You shoot the bird by the gold mine.
When u get the crab, u go 2 the hot tunnel thing and use the water 2 cool it down
first instrument is a crab shell and was hit with a bird beak
You get the helicopter and the fish sticks and catch the crab to get Gregs money back.
use the fish stickes from freglys mom. then go to the water and put it above the crab.
you use it when your near fregly and he gives you a blotter for the early bird bingo
Answer: Go to your items and click use on your fish sticks item. Then your person will say something like this,"Maybe i can use the fish sticks as bait" Then go over by the beach where the crab is. And use "the bait". Then the crab will grab onto the helecopter.
o.k you have to use the pea shooter to shoot the key off of the bird(the bird is a little ways to the left)then get the key, get in front of the door, & use the key(in items)