Information is definitely out-dated, and you shouldn't really take it to heart.
Sand Crabs are NPCs that spawn from crates, or from one of King Crab II's attacks. They are able to trip the player when touched. These are an enormous threat, even to the well prepared, as they are extremely hard to hit.
As it turns out, crabs are very protective of their fellow species. When you decided to end King Crab II, they started rising. They look cute, but they're snappy and will kill you, so you're gonna have to put them down. They're also great for cooking, if you don't mind the crunchy sand.
- It's advised to bring explosives, such as the RPG, a Grenade, or a Molotov as these spawn in groups when their crates are destroyed.
- Don't rely on camping on the sand castles as they can barely jump above them. Try camping on the lighthouse instead as they can't jump upon there. You should also be careful on the lighthouse because they can easily knock it down.
- If they do knock down the tower, you can use your Parasol to slow down your fall.
- There's a chance the lighthouse will be launched off the map by them, which can kill you too.
- These should be killed on sight, as these will instantly stun you if they touch you.
- One of these can easily keep you tripped until you die.
- If you are at a far enough distance, you can easily dodge its leaps by sidestepping.
- Try to find the pattern of when they will leap.
- Also, do not walk or run in a straight line.
- Use a Jetpack so you can escape the horde of these, but be advised of the fuel, you can quickly fall to your death if you're not paying attention.
- If you do run out of fuel, use the Parasol.
- It will take a bit of fuel and time before you are out of the Sand Crab's range, so move around.
- Stay away from the crates. Stay at a medium or far range to prevent the group of Sand Crabs stunning you once it breaks open.
- Keep in mind players may attempt to release crates next to you, either for trolling or eliminating competition for the rewards.
- Sometimes when attacked by a Sand Crab, you will lose your arms and legs. You may still move but you are completely incapacitated from attacking or using Items.
- When survivors are far from its range, it can leap around freely in any direction.
- These had to be nerfed from Debug as they were very hard to kill.
Just in case, here is a link to the Mini Crab.