The element calcium (Ca) supports all animals in two main ways; it builds their skeletons and supports their muscle and nerve function. Ca is the basic mineral in vertebrate teeth and bones and invertebrate (think clams and lobsters) shells and carapaces. It is also the crucial trigger for contraction in muscles, and it initiates impulses in nerves.
Without an adequate supply of calcium over the long-term your teeth, vision and brains are damaged, and your bones become brittle. You suffer from osteoporosis. Given all these roles it is no surprise that humans and other animals need a lot of Ca.
Calcium forms about 6% of our body weight, ignoring our water content. The Ca needs of aquatic animals range from lows of 0.1% or less in some non-crusty plankton to 10 to more than 20% in turtles, snails, crayfish, and crusty animal plankton such as Daphnia. Given this range in need, it is no surprise that calcium decline in lakes first affects calcium-rich animals such as crayfish and Daphnia.
Calcium is as important to plants as it is to animals. Although they don’t need quite as much as animals, needs do vary among plant species. For example, sugar maple need about 5 times more Ca than conifers, and are thus more sensitive to Ca decline in the soil. In plants, as in animals, Ca plays both structural and physiological roles. Calcium forms an essential mineral that holds cells of plants together in proper alignment. Too little Ca and root tips and young leaves don’t grow properly. Ca also serves as a messenger in plant signalling. With inadequate Ca, plants can’t properly defend themselves against invaders, as they can’t properly signal the attack.