Ch 10

• What traits do you share with:

  • A jellyfish
  • An earthworm
  • A chimpanzee
• Heterotrophs


  Animals that obtain food from their environment
• Autotrophs


  Organisms that make their own food (like plants)
• Biologists hypothesize that the first animal evolved around 600 million years ago
• Design a test that you could perform that would allow you to make a definitive conclusion
• Sponges


  • Lack body symmetry and tissues
  • Mostly marine
• Cnidarians


  • Radially symmetrical
  • Have tissues and stinging cells
  • Mostly marine
• Sponges have the longest evolutionary history of all animals
• Characteristics of sponges


  • Asymmetrical shape
  • Lack tissues
  • Sessile
  • Every cell must be in contact with the environment
• Characteristics of cnidarians


  • Radial symmetry
  • Cells organized into tissues
  • Stinging cells
  • Two distinct body forms: polyp and medusa
• True or false: Cnidarians, including jellies, may predate dinosaurs by some 200 million years
• True or false: Most corals obtain the majority of their energy from photosynthetic unicellular algae that live within the coral's tissue
• True or false: Jellies can sting you even after they are dead
• The animal kingdom includes three phyla of worms with separate lineages
• Flatworms, annelids, and roundworms


  • Share similar body shape, but vary considerably
  • Each phylum has its own evolutionary heritage and distinctive features
• Flatworms


  • Lack a digestive tract
  • Bilateral symmetry
  • Gastrovascular cavity
  • No true body cavity
  • Eyespots
  • Sex organs
  • Some are parasites
• Annelids


  • Bilateral symmetry
  • Complete digestive tract
  • Closed circulatory system
  • Body cavity
  • Body segments
• Roundworms (nematodes)


  • Bilateral symmetry
  • Complete digestive tract
  • No body segments
  • Cylindrical bodies tapered at both ends
• Can you think like a zoologist?
• Zoology (from the Greek zoon, animal + logos, to study) is the study of animals including their growth, development, function, distribution, and origin
• What types of questions does a zoologist ask?
• Thinking like a zoologist, describe an observation you have made about an animal?
• Generate a question and a hypothesis
• How might you test your hypothesis?
• Mollusks


  A phylum of soft-bodied animals, many of which are protected by a hard shell
• Examples of mollusks


  • Snails and slugs
  • Oysters and clams
  • Octopuses and squids
• Characteristics of mollusks


  • Bilateral symmetry
  • Three main parts: muscular foot, visceral mass, and mantle
  • Open circulatory system
  • External shell (most)
  • Gills (most)
  • Radula—file-like organ
• All animals, besides the cnidarians, exhibit bilateral symmetry: they can be split into roughly mirrored halves by slicing down the midline
• The precise evolutionary importance of bilateral symmetry is still an area of active research
• Identify at least one possible advantage of having bilateral symmetry, including having a head and a tail
• Be prepared to explain your reasoning
• Arthropods


  • The most numerous and diverse phylum of animals
  • Common groups: arachnids, centipedes and millipedes, crustaceans, insects
• Characteristics of arthropods


  • Bilateral symmetry
  • Body segments: head, thorax, and abdomen
  • Hard exoskeleton
• Arachnids


  • Eight-legged arthropods
  • Most are terrestrial carnivores
• Crustaceans


  • Common arthropods in marine and freshwater habitats
  • Many are valuable food crops (shrimp, lobster, crabs, etc.)
• Insects, by far, outnumber all other animals combined
• Most insects have easily recognizable segments (head, thorax, and abdomen), three pairs of legs, and one pair of antennae
• True or False?
• Explain your choice:
• True or false: There more kinds of insects on Earth than any other kind of animal