The history of sea urchin exploitation in most countries has been one of dramatic growth leading to over exploitation and the collapse of stocks and the industry. If a sea urchin processing industry were to be developed in Shetland great care would have to be taken to ensure that the fishery was carried out on a carefully managed and sustainable basis. The podia tips are flattened to form powerful suckers which can grip rock, kelp or other surfaces. These powerful teeth form a complex chewing mechanism which can effectively graze or masticate an impressive variety of materials. While they are normally inclined to eat growing kelp or kelp debris, sea urchins are in fact omnivorous and if hungry enough will eat almost anything within reach.
Most sea urchins are dioecious, i.e. the sexes are separate.
The female ovaries have a somewhat granular appearance, due to the presence in them of eggs, whereas the male gonad has a finer texture. In Shetland sea urchins start to spawn from early March, with maximum activity in April, and continue on perhaps until the end of July. A mature sea urchin, opened during December, showing the creamy coloured roe. The potential season for sea urchin harvesting in Shetland would appear to last from December through to late February, just before the start of the spawning season. Additional harvesting might prove to be viable during October and November.