As crabs grow, they shed their entire shell, are briefly considered ‘soft shell’ and grow into a larger shell. So at different times in this cycle, you could buy what looks like a huge crab, but when you crack it open there is barely any meat in it – because it is still growing into its new ‘larger’ shell.
So both live and cooked crabs should feel heavy for their size and have a tough shell.
You can test the hardness of a crab shell by turning it on its back and pressing with your thumb on various parts of the white underside of the body or carapace.
If it is very firm, that’s a ‘full crab’ if you can push on the underside of the carapace and it is flexible – the crab is still in the growth phase of filling out the meat in its shell and is in the process of ‘hardening up’ the shell.
No type of crab, cooked or raw or live – should smell like a fish, or ammonia or have damaged or missing parts.
If you are buying live crabs that have their claws tied up, it means they haven’t eaten any crab dinner since they were tied up (they use their claws to eat – like hands). So they are gradually wasting away.
Freshly caught live crabs that have eaten recently aren’t sluggish. So look for active crabs. If the sand crab or any other kind of live crab is being kept in a chilled environment that will make them sluggish also.
Check the crab for any broken limbs or holes in its shell (pictured). You want a perfectly intact shell with nothing missing: two arms with both claws fully intact, four legs with the pointy foot attached and two rear legs with swimming paddles attached.
Sand crabs are often cooked when they are at their best (steamed or boiled), then offered for sale ready for the customer to take home and clean out the gills and guts, then serve or pick out (yield) the meat to serve.
Before they are sold they are kept in an environment that is either refrigerated or chilled with ice to keep them fresh. But they do eventually go bad, all seafood has a limited shelf life.
Check how it smells! The crab should smell fresh and slightly salty, but definitely not fishy or like ammonia.
The crab should also have a firm shell and feel heavy for its size.
Green Crabs (Raw & Dead):
When we talk about seafood, ‘Green’ doesn’t refer to colour, it means dead and uncooked. Like raw prawns – dead and uncooked prawns are referred to as ‘green’ prawns. It’s the same with sand crabs, lobster tails, and Moreton Bay bug tails.
A portion of the sand crabs a fishmonger may have for sale will be dead, cleaned of their innards and sold ready to be cooked.
Smell is the most important indicator when buying green crabs. If they smell overly fishy or have an ammonia smell don’t buy those crabs!
Don’t ever buy frozen crabs if you can avoid it. The process of freezing and thawing crab meat removes much of the flavour and damages the crab meat.
Be especially cautious not to buy frozen whole crabs, as they haven’t been cleaned (involves removing the crab organs and semi digested food the crab has been eating).
Another significant disadvantage of buying frozen crabs is you don’t know what kind of health or state of decay they were in when they were frozen, or how many times in the shipping and storage phase that they partly or entirely defrosted and were semi or fully frozen again.
Crabs ‘On The Half Shell’:
Are dead crabs, cooked or raw, frozen or not… they have simply been cleaned properly of their gills and guts and had the top of the shell and the flap (that includes from where they discharge their excrement) removed.
You are left with a clean crab body and limbs consisting only of meat and shell.
This is a more premium preparation, done with bulk buyers in mind. If you can by blue swimmer crabs this way – jump at the opportunity.
Soft Shelled Crabs:
When a blue crab has just shed it’s hard shell and is ready to grow into its new shell – for that brief part of the day – they are called soft shared crabs.
They have to be caught at this ideal time. So the best soft shelled crabs are bought fresh or cooked at the source!