しおひがり （潮干狩り）

I have a coworker that is really good at Japanese vocabulary. And the staff asked him this random word and he (based on the core words i guess) popped out with "clam digging" which was correct. BUT! 潮干［しおひ] does not mean clam it means 'low tide' and! 狩り［かり] doesnt mean dig either. It means to 'hunt' so this litterly 'low tide hunting' ... by the way, if you dont know 'clam' is *something* with 貝［かい], there are many types. 貝 it self just means shell fish i think.