Odd crab behavior

[Mech]

A friend and I were recently out on a private beach scouting for geoducks.
It was a -3.2 tide and we were walking in the sea grass area.

We didn’t see any geoduck vent tubes but saw probably 100 gaper tube’s snouts and crab everywhere.
Lots and lots of mainly juvenile dungies  in shallow water.

So walking around in the shallow water I see what I think is a crab molt and it’s really big.
I gently kick it a few times because it is half buried and then it jumps up mad and scurries off.
I’m like wtf?
Is this a big female laying eggs?
We then see several more all half buried all extra large in size, looking male and some even were confirmed male.
These were all easily over 7 inches and one even bit my boot hard.

Why are these crab half burying themselves?
One or two wouldn’t really make me wonder but we saw four or so so had had to be doing this for a reason.

I’ve seen eagles grab large crab here in the shallows before too.

[HntnFsh]

I don't know why they do it. But suspect dropping eggs. I've dug up sevetal crab a foot deep while clam digging.

[Griiz]

Maybe this:

Soon after the live crab has exited (the larger, green crab in adjacent photo) they bury themselves in sand to allow their new shell to harden. Adult crab populations tend to molt simultaneously, Females in the spring, Males in the late summer. It often produces a scene like this one

[Bareback]

Crabs frequently dig in.  In deeper water with strong currents they dig in to avoid being swept away. They are in the eel grass to jump all the honeys coming in to lay eggs. Instead of going out with the tide they dig in. Before I had a boat crabbing was a minus tide wading through crab grass.   I’d  tow a cooler behind me and use a pitch fork. Slide the fork under them and they clamp on. Lift and measure. Some days were very productive.

[Rob]

Normal behavior.   When diving we use to see them buried all the time.  Takes them about 10 seconds to bury to their eyestalks.

Fun to coax them out-they run away with sand on their backs and it streams away as they run.  It looks like smoke and they are on fire!

[Rob]

Think of it as protection.  When buried they are very hard to see and predators may pass them by.

Flounders do the same thing-just buggy eyes sticking up.

When your home is open sand you make your own cover!

[AL WORRELLS KID]

Think of it as protection.  When buried they are very hard to see and predators may pass them by.
Flounders do the same thing-just buggy eyes sticking up.

I too, have noticed this laying low "Survival Behavior" before, especially the Older Adults... trying to hide out, in plain sight. 

[Mech]

Just to give this subject an update,

These last few days my friends and I have been taking advantage of these nice low tides hunting geoducks.

We did see several crabs doing this and some were even locked up doing what I think was “the wild thing”.
I never knew that they locked up.
For some reason I thought they did the spawn thing like fish.
Some were face to face some were belly to belly.
Not that this means much but those that were locked up were of opposite sex.

[Rob]

As I recall, the females can be mated after a molt.  So the males will pick up a female and carry her around until she molts.  I have always seen them belly to belly under the males claws.

[STIKNSTRINGBOW]

These 2 were kissing.

[Mech]

Ha Ha.