Rennet, the stomach contents of an unweaned animal; also, the membrane lining the stomach. The word rennet also refers to preparations that contain the enzyme rennin and that are used in curdling milk. The chief source of rennet is the fourth stomach of young calves. Rennet is used in making cheese, junket, and medicinal preparations. It is also used to coagulate casein (a milk protein) in making plastics.
The golden toads of the Monteverde Cloud Forest Preserve, a rain forest in the mountains of Costa Rica, were numerous and easy to find as recently as 1987. Lately, the sound of these amphibians has been quiet. Find out why.
The sea urchin is a prickly-looking marine animal that is spherical in shape and covered with long movable spines.