First of all...please clean the clams in water nicely to remove dirt and sand and follow the above video....That's how its done at home and in most of the households down south.
I know I know....not everybody has that kind of weird looking scary knife/sickle/weapon(whatever they call it)....MOOTATHANE (in tulu)....so there is an easier method which I learnt from my Goan friend in Bahrain.
Pop the clams in the freezer for 20 to 30 minutes...remove....chuck it into a vessel with room temperature water...after few second they will open up... Separate the shells slowly, you will notice that there will be more flesh on one shell, using that shell scrape out the remaining flesh from the other shell and throw away the empty one....simple.
Now I saw this on Nigella Lawson show where she had mentioned ....to throw away the clams that do not open up....supposedly they are the bad/evil ones...so I do listen to Nigella and throw away the ones that do not open.....But mom does not care....open or not she rips its apart with her weapon.
I am no expert on clams...whatever little I know...learnt it from mom ......So if anyone else has any input in this matter please feel free to comment...rather than saying to yourself 'ee ponnage dada gothuji ' (translation- this girl does not know anything).....yes I am talking to all the beautiful Mangalorean aunties out there :)