hi I am Rupert I am 8 years old and my dad Eliot uses this site


we have been looking at beach's in Tasmania and we are wondering if there are bigger crabs under bigger rocks.

we went to a rocky beach and noticed that there were bigger crabs under bigger rock's because there were bigger gaps under them. we think they were shore crabs.

we went to a beach with big bolder rock's. dad's hypothesis was that we will find bigger crab's. my hypothesis was we will find no crab's and I was right!

I want to find out are there bigger crab species normally in rocky beach's

thank you for all your help

Hi Rupert,

Great question - and well done for having hypotheses to go out and test! In general crabs like to find gaps that are big enough for them to get into, but only just. That way it is hard for a predator to pull them out, even if they find them. So you are right - it's not the size of the rocks so much as the size of the gaps than matters. I don't know for ceratin, but my hypothesis would be that on the boulder beach the gaps were just too big to be safe hiding places for any crabs at all.