Feeding and Digestion All animals are heterotrophic. The structure or form of an animal’s mouth parts determines how its mouth functions. After obtaining food, all animals must digest it, either in specialized cells or organs. Copyright © McGraw-Hill Education Animal Characteristics

Support Between 95-99 percent of animals are invertebrates – animals without backbones. Many invertebrates are covered by exoskeletons, which are hard or tough outer coverings. Some invertebrates have an internal support structure called an endoskeleton. If an animal has an endoskeleton and a backbone, it is called a vertebrate. Copyright © McGraw-Hill Education Animal Characteristics

Habitats Animal adaptations around feeding, digestion, and support allow them to live in a variety of habitats. Invertebrates and vertebrates are found in terrestrial, marine, and freshwater ecosystems. Copyright © McGraw-Hill Education Animal Characteristics

Animal Cell Structure Animal cells do not have cell walls. The cells of all animals except sponges are organized into tissues, which have specialized functions. Copyright © McGraw-Hill Education Animal Characteristics

Movement Evolution of nerve and muscle tissue allows animals to move in unique ways. Some animals are stationary as adults, but most have a body form that can move during some stage of development. Copyright © McGraw-Hill Education Animal Characteristics

Reproduction Most animals reproduce sexually. Some animals are hermaphrodites, meaning the produce both sperm and eggs in the same body. Fertilization occurs when the sperm penetrates the egg to form a fertilized egg called the zygote. Internal fertilization occurs when sperm and egg meet inside an animal’s body. External fertilization occurs when sperm and egg meet outside an animal’s body. Copyright © McGraw-Hill Education Animal Characteristics

Reproduction Asexual can occur through: Budding – offspring develops as a growth on the parent body Fragmentation – parent breaks into pieces that develop into adults Regeneration – a new organism can grow from a lost body part Parthenogenesis – egg develops in a female without fertilization Copyright © McGraw-Hill Education Animal Characteristics

Reproduction Early development The zygote undergoes mitosis and a series of cell divisions to form new cells. The cells continue to divide, forming a fluid-filled ball of cells called the blastula. The blastula continues to undergo cell division, and some cells form a gastrula, a two-cell-layer sac with an opening at one end. Copyright © McGraw-Hill Education Animal Characteristics

Development of a Zygote Animation FPO Add link to concepts in motion animation from page 696 (Figure 5) here. Copyright © McGraw-Hill Education Animal Characteristics

Reproduction Tissue development The inner layer of the gastrula develops into the endoderm, which forms the digestive organs. The outer layer of the gastrula develops into the ectoderm, which becomes the nervous system and skin. The mesoderm forms between the ecto- and endoderm, and forms the muscle, circulatory, excretory, and respiratory system in some animals. Copyright © McGraw-Hill Education Animal Characteristics

Review Essential Questions Vocabulary How do adaptations enable animals to live in different habitats? How is structure and function related in animals? What are the stages of embryonic development in animals? Vocabulary invertebrate exoskeleton endoskeleton vertebrate hermaphrodite zygote internal fertilization external fertilization blastula gastrula endoderm ectoderm mesoderm Copyright © McGraw-Hill Education Animal Characteristics