Couldn't find element LayerAd

Error finding content

Kingdom Animalia - Windows to the Universe

Kingdom Animalia

With over 2 million species, Kingdom Animalia is the largest of the kingdoms in terms of its species diversity. But when you think of an "animal", what image comes to mind? While mammals, birds, reptiles, amphibians, and fish are the most familiar to us , over half of all the animal species belong to a group of animals known as arthropods. Arthropods include animals such as centipedes, crabs, insects, and spiders. And with over a million species of arthropods, this means that the majority of animals species come from a group of critters that give most folks the creeps!

So, what exactly is an "animal"? With so much diversity among different animal species, it's difficult to imagine what they all might have in common. First, animals are "multicellular" (composed of many cells). In most animals, these cells are organized into tissues that make up different organs and organ systems. Second, all animals are heterotrophs (= "other feeder"), meaning that they must get their food by eating other organisms, such as plants, fungi, and other animals. (Plants are referred to as autotrophs or "self feeders") because they produce their own food by the process of photosynthesis.) In addition, all animals require oxygen for their metabolism , can sense and respond to their environment, and have the capacity to reproduce sexually (though many reproduce asexually as well). During their development from a fertilized egg to adult, all animals pass through a series of embryonic stages as part of their normal life cycle. Though frogs and humans don't look very much alike, we share many features in common during our embryonic phase.

Last modified October 15, 2011 by Jennifer Bergman.

Shop Windows to the Universe Science Store!

Traveling Nitrogen is a fun group game appropriate for the classroom. Players follow nitrogen atoms through living and nonliving parts of the nitrogen cycle. For grades 5-9.

Windows to the Universe Community



You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Kingdom Plantae

Kingdom Plantae contains almost 300,000 different species of plants. It is not the largest kingdom, but it is a very important one! In the process known as "photosynthesis", plants use the energy of the...more


Autotrophs are organisms that can "make their own food" from an inorganic source of carbon (carbon dioxide) given a source of energy. Most autotrophs use sunlight in the process of photosynthesis to make...more

Analysis of Protein from T. rex Bone Confirms Dinosaurs' Link to Birds

For a long time, scientists have suspected that birds are dinosaurs' closest living relatives. They came up with this hypothesis based on the shapes found in bird and dinosaur skeletons. Now scientists...more

Exploratour - Life on Earth

Between 2 and 3 million species are currently known on Earth and new species are being discovered every year. From tiny yeasts to starfish to blue whales, the diversity of life is pretty awesome! With...more

Biomes and Ecosystems

Biomes are large regions of the world with similar plants, animals, and other living things that are adapted to the climate and other conditions. Explore the links below to learn more about different biomes....more

Explore the Wetlands of Brazil!

"People outside Brazil know only the Amazon. . . it's a shame because the Pantanal is a very important ecological place." -- Dr. Maria Pádua, Former Director, Brazil's National Parks The Pantanal wetland...more

Kingdom Protista

Members of the Kingdom Protista are the simplest of the eukaryotes. Protists are an unusual group of organisms that were put together because they don't really seem to belong to any other group. Some protists...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF