Van Veen grab sampler
The Van Veen Grab Sampler is limnological instrument to sample sediment in the ocean. Usually it is a clamshell bucket made out of stainless steel. Up to 20 cm deep samples of roughly 0.1 m2 can be extracted with this instrument. It is light-wight (roughly 5 kg) and low-tech. The smallest version even fits into hand luggage. A draw-back is that it tends to disturb the sediments more than a hydraulically damped corer, it is not designed to sample living organisms.
Mechanism
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 unlock when hitting the ground. When the rope is pulled upward again, the two buckets close and grab a sample from the sea floor.
External links
Instrument description at Woods Hole Oceanographic Institute