Animalia

Kingdom Animalia

Great Bay Estuary hosts a diverse assortment of animals. Even a tiny sampling of community members—worms burrowing into the mudflats, crabs scrambling into rocky crevices, large sport fish running down a school of minnows, mice nibbling at marsh plants, and hawks soaring on an aerial hunt—demonstrates the wide variety of their forms and lifestyles. But they all share certain characteristics, traits that make them animals.

None produce food. Animals are consumers, relying on photosynthetic plants, algae and some bacteria to create organic compounds. Even the carnivores ultimately depend on photosynthesis, the cornerstone of the food pyramid.

Every animal begins life as a zygote, the combination of two sex cells, each with half the necessary amount of genetic material. Fertilization, the fusing of these cells, takes place either internally (e.g. birds), or externally (e.g. oysters releasing their sex cells simultaneously into a current).

Only in animals [except sponges] does the zygote grow through a series of cell divisions into a ball, called a blastula. In most animals the ball is hollow, with an embryo developing on one end of the inside. The outer layer forms the placenta through which gases, nutrients and waste are exchanged.

Animals are multicellular, as are plants and many algae species. But animals are unique with their diverse kinds of cells arranged into tissues that form specialized organs. These organs function in systems like digestion, circulation, or secretion. Also, plant cells have rigid cell walls, while animal cells have membranes.

Most animals have a nervous system and a brain, which allows them more advanced responses to stimuli than organisms of the other kingdoms.

For a sampling of animals found in the habitats of Great Bay Estuary, check out the drop down menus under the Kingdom Animalia link.