Unit 8 - Lesson 1 - Animal Characteristics

​Lesson 1

Animal Characteristics

General Animal Features

•The ancestral animals were eukaryotic and multicellular.

•They developed adaptations in structure that enabled them to function in
numerous habitats.

•All animals share some common features.

Animal Characteristics
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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.

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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.

Animal Characteristics
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Multiple Choice

animal without a backbone

• Exoskeleton

• Invertebrate

• Endoskeleton

• Vertebrate

Multiple Choice

animal with a backbone

• Exoskeleton

• Invertebrate

• Endoskeleton

• Vertebrate

Multiple Choice

A body covering, typically made of chitin, that provides support and protection

• Exoskeleton

• Invertebrate

• Endoskeleton

• Vertebrate

Multiple Choice

internal skeleton or supporting framework in an animal

• Exoskeleton

• Invertebrate

• Endoskeleton

• Vertebrate

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.

Animal Characteristics
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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.

Animal Characteristics
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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.

Animal Characteristics
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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.

Animal Characteristics
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Multiple Choice

an organism that has both male and female reproductive organs

• Endoderm

• Hermaphrodite

• Ectoderm

• Gastrula

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

Animal Characteristics
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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.

Animal Characteristics
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Multiple Choice

An embryonic stage in animal development encompassing the formation of three layers: ectoderm, mesoderm, and endoderm.

• Endoderm

• Hermaphrodite

• Ectoderm

• Gastrula

Multiple Choice

A hollow ball of cells that marks the end of the cleavage stage during early embryonic development in animals.

• Blastula

• Hermaphrodite

• Mesoderm

• Gastrula

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.

Animal Characteristics
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Multiple Choice

outermost germ layer; produces sense organs, nerves, and outer layer of skin

• Endoderm

• Hermaphrodite

• Ectoderm

• Gastrula

Multiple Choice

the inner germ layer that develops into the lining of the digestive and respiratory systems

• Endoderm

• Hermaphrodite

• Ectoderm

• Gastrula

Multiple Choice

middle germ layer; develops into muscles, and much of the circulatory, reproductive, and excretory systems

• Endoderm

• Hermaphrodite

• Mesoderm

• Gastrula