Here the fingers of both the hands are interlocked with each other.

Lets take a look at the Viniyoga shloka (uses)
Sammuhagamane tundadarshane shankhapurane
anganam motane shakhonnamane cha niyujyate
This verse says that Karkata is used to denote

Arrival of people (Get together)
Showing the Belly
Blowing the counch
Twisting and stretching of Limbs
Bending a branch

Return to Samyukta hasta