Shop Windows to the Universe

Young Voices for the Planet DVD in our online store includes 8 films where students speak out and take action on climate change.

Kingdom Animalia

With over 2 million species classified into 30 phyla, Kingdom Animalia surpasses the other 4 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 single phylum -- the arthropods! Arthropods include animals such as centipedes, crabs, insects, and spiders which all share in common hardened exoskeletons, jointed appendages, and fused body segments. And with over a million species of arthropods, this means that the bulk of animal diversity of Earth belongs to a group of organisms 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 obtain energy and nourishment by consuming other organisms. (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. In many respects, the embryonic phases are quite similar across animal groups.

Last modified October 15, 2011 by Jennifer Bergman.

Shop Windows to the Universe Science Store!

"Science, Evolution, and Creationism", by the National Academies, provides fascinating background on these topics for all, and is particularly useful for the Earth and space science classroom. Check our other books in our online store.

Windows to the Universe Community

News

Opportunities

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

Though not the largest kingdom, with a mere 300,000 species catalogued, many might argue that the Kingdom Plantae just may be the most important group of living organisms. In the process known as "photosynthesis",...more

Autotrophs

Autotrophs are organisms that produce organic compounds from an inorganic source of carbon (carbon dioxide) given a source of energy. If the source of energy is the reactions of inorganic chemical compounds,...more

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

Scientists have put more meat on the theory that dinosaurs' closest living relatives are modern-day birds. Molecular analysis, or genetic sequencing, of a 68-million-year-old Tyrannosaurus rex protein...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

Joanna Hubbard

This is my 10th year with the Anchorage School District as a science teacher, currently working with K-12 teachers around the district rather than in a classroom. My most recent classroom time was as a...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 some of the...more

Explore the Wetlands of Brazil!

"The Pantanal has the greatest concentration of fauna in the Americas. People outside Brazil know only the Amazon. . . it's a shame because the Pantanal is a very important ecological place." -- Dr. Maria...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA