Shear legs to the gin pole, derrick and tripod (lifting device). Shears are an A-frame of any kind of material such as timbers or metal, the feet resting on or in the ground or on a solid surface which will not let them move and the top held in place with guy-wires or guy ropes simply called "guys". Shear legs only need two guys whereas a gin pole needs at least three. The U. S. Army Field Manual FM 5-125 gives detailed instruction on how to rig shears. Fixed shear legs are most commonly found on floating cranes known as floating sheerlegs.
Crown-of-thorns starfish of the fauna of most coral reefs and the effects of "A. planci" populations on coral reefs are very dependent on the population density. At low densities (1 to perhaps 30/hectare) the rate at which coral is being preyed upon by the starfish, is less than the growth rate of the coral, i.e. the surface area of living coral is increasing. The starfish may, however, influence the coral community structure. Because the starfish don't feed indiscriminately they may cause a distribution of coral species and colony sizes that differs from a pattern without them. This is evident by comparison of