Animal Kingdom

Characteristics:

• Eukaryotic
• Don’t have cell walls
• Ingest/digest food
• mobile
• Reproduce sexually and produce an embryo that undergoes a state of development

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Characteristics Used to Classify Animals

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Levels of Organization:

• Classified based on the differences in their tissues and organ systems
• Most animals have cells that are organized into tissues (except sponges)
  • Tissue: a group of similar cells that perform a specific function (organized into organs and organ systems)

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Number of Germ Layers:

• Most animal have three layers
  • Ectoderm- Outer Layer, (skin, nerve tissue, sense organs)
  • Mesoderm- Middle layer (muscles, blood, kidneys, reproductive organs)
  • Enderm- inner layer (lungs, liver, pancreas, bladder, stomach lining)
• Classified based on whether they have 123 germ layers

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Symmetry and Body Plans:

• Asymmetrical Body Plans: body is an irregular shape eg. sponges
• Symmetrical body plans: radial symmetry can be divided along any plane into roughly equal halves
• Bilateral symmetry: Can be divided along one plane into 2 equal halves

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Body cavities:

• Coelum: fluid-filled body cavity that provides space for the development and suspension of organs and organ systems.

  - organs are contained in the body cavity

• Can be:

  • coelomate: have
  • Acoelomate: without
  • pseudocoelomate is similar to coelom but lacks a layer of cells

• Advantages: allows for quick responses and movement and development of complex organs

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Digestive system:

• No digestive system (sponges)
• Incomplete digestive system: only one opening, food goes in and waste comes out of the same hole
• Complete digestive system: digestive tube has 2 openings
• Protostome: mouth develops first
• Deuterostome: anus develops first

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Segmentation:

• The division of the body into repetitive segments or sections
• Advantages: If one section is damaged, the rest continue to work. Mobility is also more effective

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Movement:

• Most animals are mobile
• Sessile: some animals are stationary and stay in one place, but at some point in its early stages it had movement

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Reproduction:

• Reproduce sexually
• produced by either external or internal fertilization
  • External: fertilization happens outside of the body
  • Internal: Gameters combine inside the body

*some animals like aphids reproduce sexually/asexually

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Nervous System:

• Some have it, some don’t
• Cephalization:
  • nervous tissue is concentrated at one part of an organism (eg. the brain)
  • Ceph: means brain

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