First cover all the holes, then dig a hole and put bamboo at the bottom. There should be no holes, just a hole on the top. After the fiddler crabs get in, take out the bamboo tube and reach out to catch it. That's it.

Fiddler crabs live on salt and brackish water beaches, in muddy areas, and live a camping cave life, often with specialized burrows that often change every few days. once. The depth of excavation is related to the water table. Digging depth can reach 30 cm.

Generally speaking, the bottom of the excavation needs to reach moist soil. Many male crabs also build a semicircular umbrella-shaped lid to cover the entrance of the hole. The activities of crabs follow the ebb and flow of the tide with certain regularity. At high tide, stop at the bottom of the cave. When the tide is low, it moves along the beach to provide food and repairs to the cave. Finally, occupy the cave and prepare for mating.

Extended information:

Fiddler crabs arrange their own rhythm of life according to the rise and fall of the tide. They go out when the tide goes out and go back when the tide rises. And it can accurately change color day and night. The body color of fiddler crabs changes alternately between day and night. At night, the body color becomes lighter, and during the day it becomes darker and brighter. The time when the body color contrast is most obvious is exactly 50 minutes later than the previous day, which also coincides with the rise and fall of the sea water every day.

This extremely regular life rhythm is obviously the result of biological clock control and is the result of hundreds of millions of years of evolution of this species.