Animal heterotrophy distinguishes itself from fungal heterotrophy in several ways. While both animals and fungi are heterotrophs, the main difference lies in how they obtain their nutrition. Most animals derive their nutrition by consuming living prey, rather than dead prey. They use enzymes to digest their food, and some animals even prey on other animals by ingesting them. In contrast, fungi obtain their nutrition by absorbing nutrients from dead organic matter in their environment. They secrete enzymes onto the organic matter, breaking it down into smaller molecules that can be absorbed by the fungi. 57) Animals have several unique characteristics. These include the presence of a structural carbohydrate called chitin, a nervous system that allows for signal conduction and muscular movement, cells that contain mitochondria, and the ability to obtain nutrition through heterotrophy. Additionally, some animals have flagellated gametes.