Grabs

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Grab sampling is the process of bringing up surface sediments from the seafloor. Once it is launched, the jaws of the grab sampler open and it descends to the seafloor. A spring closes the jaws and sediments, or loose substrates, are trapped. The grab sampler is then brought up to the surface where its content is studied in detail. ​

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The type of equipment selected for sampling seabed substrata and the benthic macrofauna is primarily determined by the hardness or compactness of the substrata. Whilst a wide variety of sampling methods are available, only a small proportion of these can effectively collect samples from areas of relatively coarse sediments, which are characteristic of such sites. 

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In certain situations, it may be necessary to use more than one technique to sample the full range of benthic organisms present in an area.