While letting the instrument down into the water, the two
levers with
buckets at their ends are spread like an open scissor. The levers are locked in this position, and unlocked on hitting the ground. When the rope is pulled upward again, the two buckets close and grab a sample from the
sea floor. File:VanVeenGrab - Locked.jpg|Van Veen grab when it is locked, ready to be lowered to the floor File:VanVeenGrab - Unlocked.jpg|It is now unlocked after hitting the floor, ready to collect sediment File:Van Veen Grab - Close.jpg|When lifting it after unlocked, the jaws will close to collect sediment inside Three small technical changes lead to variations with more mechanical parts or structure: • The
Ekman grab sampler does not close the
shovels instantly on ground contact, but a messenger weight has to be sent down in order to release springs and take the sample. • The
Ponar type sampler is modified also and has additional springs which are released upon bottom contact which might be helpful for harder surfaces. • The
Young modified grab sampler includes a metal frame for additional stability. ==See also==