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animal characteristics - Coggle Diagram
animal characteristics
General Animal Features
characteristics
- Animals are multicellular heterotrophs that have evolved to live in many different habitats.
- Animals are eukaryotic have membrane-bound organelles.
- Animals do not have cell walls.
- The cells of all animals, except sponges, are organized into structural and functional units called tissues.
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Recall that biologists have created an evolutionary tree to organize the great diversity of living things.
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All present-day animals might have evolved from choanoflagellates, which are protists that formed colonies in the sea 570 million years ago.
Choanoflagellates, such zoothamnium, might have been the earliest true animals.
As animals evolved from this multicellular ancestor, they developed adaptations in structure that enabled them to function in numerous habitats.
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Feeding and Digestion
Animals are heterotrophic, so they must feed on other organisms to obtain nutrients.
A sea star obtains its food from a clam it has pried open, and a butterfly feeds on nectar from a flower.
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After obtaining their food, animals must digest it.
Some animals, such as sponges, digest their food inside specific cells.
Others, such as earthworms and humans, digest their food in internal body cavities or organs.
Animal Cell Structure
The cells of all animals, except sponges, are organized into structural and functional units called tissues.
A tissue is a group of cells that is specialized to perform a specific function. For example, nerve tissue is involved in the transmission of nerve impulses throughout the body and muscle tissue enables the body to move.
No matter where an animal lives or what adaptations it has, its cells do not have cell walls.
movements
The evolution of nerve and muscle tissues enables animals to move in ways that are more complex and faster than organisms in other kingdoms.
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Some animals are stationary as adults, yet most have a body form that can move during some stage of development.
Support
Just as animals digest their food in different ways, they support their bodies in different ways.
Vertebrates—animals
If an animal has an endoskeleton and a backbone, it is called a vertebrate.
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Fishes, amphibians, reptiles, birds, and mammals have endoskeletons made of bone.
An endoskeleton protects internal organs, provides support for the body, and can provide an internal brace for muscles to pull against.
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Invertebrates—animals
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The bodies of many invertebrates are covered with exoskeletons, which are hard or tough outer coverings that provide a frame- work of support.
Exoskeletons also protect soft body tissues, prevent water loss, and provide protection from predators.
As the animal grows, like the cicada (səˈkādə) in Figure 2, it must shed the old exoskeleton and make a new one. This process is called molting.
Some invertebrates, such as sea urchins and sea stars, have internal skeletons called endoskeletons.
Reproduction
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Animals, such as earthworms, that produce both eggs and sperm are called hermaphrodites
Hermaphrodites produce eggs and sperm at different times, so another individual of the same species is needed for reproduction.
Asexual reproduction means that a parent produces offspring that are genetically identical to itself.
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early development
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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.
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.