1. KEY CONCEPT Animals are diverse but share common characteristics.

2. The kingdom Animalia contains heterotrophic multicellular eukaryotes that develop from embryos. The invertebrates—animals that have exoskeletons and jointed legs—may be the majority of all multicellular species. 18.5 Five Kingdoms (cont.) The Kingdoms of Life The vertebrates—animals with a spinal column, or backbone—are another large group of animals. Most members of this kingdom reproduce sexually, are motile, or capable of locomotion, and have senses and nervous systems.

3. Each animal phylum has a unique body plan. Vertebrates have an internal segmented backbone. Invertebrates do not have a backbone. Arthropods make up most of the invertebrates.

4. Animals are the most physically diverse kingdom of organisms. Animals range in size from 25-meter-long blue whales to microscopic rotifers. Animals are found nearly everywhere on Earth.

5. All animals share a set of characteristics. All animals share a unique set of derived characters. Animal cells are supported by collagen. –three-stranded protein –found in bone, skin, ligaments, fingernails, and hair

6. Animals are grouped using a variety of criteria. Criteria are used to categorize animals. –Body plan symmetry –Feeding –Respiration –Circulation –Excretion –Response –Reproduction gastrovascular cavity mouth mesoglea oral arms tentacles blood vessels brain hearts muscle segment nerve cord mouth digestive track

7. There are two types of body plan symmetry. –bilateral symmetry: body divides equally along one plane Animals with bilateral symmetry can be divided equally along only one plane, which splits an animal into mirror-image sides.

8. –radial symmetry: body arranged in circle around a central axis There are two types of body plan symmetry. –bilateral symmetry: body divides equally along one plane Animals with radial symmetry have body parts arranged in a circle around a central axis.