SCIENCE

Scientists have released a new version of the tree of life, showing everything we know about how the 2.3 million living things of Earth are related to one another. (Washington Post)

Learn what criteria scientists use to classify organisms with our activity.

Teachers, scroll down for a quick list of key resources in our Teachers’ Toolkit—and check out the bolded items for some great vocabulary words!

Discussion Ideas

• The dazzling new research is a phylogenic study. What is phylogenetics?
  • Phylogenetics describes the study of how organisms relate to each other as they develop over time. Phylogenetics informs taxonomy, the study of the identification, classification, and naming of organisms.

• The new, researched “tree of life” isn’t quite as pretty as the illustration, although it’s much more of a time-sink. Where do we fit, and how are we related to slime molds, anyway? Take a deep breath, browse your own taxonomy below, and climb through the open tree of life to acquaint yourself!
  • The best way for beginners to figure out where we fit in the tree of life is to start with the specifics (our own species) instead of the generalities (we’re eukaryotes). Work your way up, through larger and larger groups (taxons) of organisms. (Each type of organism in bold includes all the taxons listed above it.) Click on the links to see great examples of each branch on the tree of life!
    • Homo sapiens. That’s us!
    • Homo. No other living thing belongs to our genus. (But lots of extinct things do!)
    • Homininae. Humans, chimpanzees, and gorillas are hominins.
    • Hominidae. Hominids include orangutans.
    • Hominoidea. Apes such as gibbons are hominoids.
    • Catarrhini. All Old World monkeys are catarrhines.
    • Simiiformes. Simians include all monkeys and marmosets.
    • Haplorrhini. Haplorhines include tarsiers.
    • Primates. Primates include lemurs and aye-ayes.
    • Euarchontoglires. Euarchontoglires include all rodents, lagomorphs (such as rabbits), treeshrews, and colugos.
    • Boreoeutheria. Boreoeutherians include animals as diverse as moles, dolphins, bats, and horses.
    • Eutheria. Almost all mammals indigenous to Europe, Africa, Asia, and North America are eutherians.
    • Theria. Therians include all mammals except monotremes (echidnas and platypuses).
    • Mammals. A mammal is an animal with hair that gives birth to live offspring. Female mammals produce milk to feed their offspring.
    • Amniota. Egg-laying animals such as birds and reptiles are amniotes.
    • Tetrapoda. Almost all four-limbed vertebrates are tetrapods.
    • Dipnotetrapodomorpha. Dipnotetrapodomorphs include the lungfish.
    • Sarcopterygii. Sarcopterygians include lobe-finned fish such as coelacanths.
    • Euteleostomi. All bony vertebrates are euteleostomes.
    • Teleostomi. Almost all bony fishes are teleostomes.
    • Gnathostomata. All vertebrates with jaws are gnathostomatans.
    • Vertebrata. All animals with backbones are vertebrates.
    • Craniata. Craniates are animals with hard skulls.
    • Chordata. All mammals, fish, amphibians, reptiles, birds, salps, and lancelets are chordates.
    • Deuterostomia. Deuterostomes are marked by unique development of their embryos—the first opening to develop (called the blastopore) ultimately becomes the animal’s anus. This group includes sea stars, snails, and eels.
    • Bilateria. Bilaterians have bilaterial symmetry: They have a front and back, left and right. Mollusks and flatworms are bilaterians.
    • Metazoa. Animals! All animals are metazoans!
    • Holozoa. All animals and some single-celled flagellates are holozoans.
    • Opisthokonta. All animals and fungi are opisthokonts.
    • Eukaryota. All creatures whose cells have organelles with membranes are eukaryotes. Slime molds are simple eukaryotes.
    • Cellular organisms. This is where we’re related to bacteria, archaea, and algae.

• Try tracing taxonomies! Use the search filters (“search for taxon”) for some help. Here are some suggestions to get you started.
  • Foraminifera or funnel-web spiders? (Quinqueloculina or Hadronyche)
  • Kelp or krill? (Laminariaceae or Euphausiacea)
  • Lilypads or lichen? (Nymphaeaceae or Parmelia)

• What is the point of this phylogenetic research?
  • It’s awesome science, and there really doesn’t need to be any other reasons. But there are . . .
    • “Understanding how the millions of species on Earth are related to one another helps scientists discover new drugs, increase crop and livestock yields, and trace the origins and spread of infectious diseases such as HIV, Ebola and influenza.”

TEACHERS’ TOOLKIT

Washington Post: This new, ‘complete’ tree of life shows how 2.3 million species are related

EurekAlert: ‘Tree of life’ for 2.3 million species released

Open Tree of Life

(extra credit!) Proceedings of the National Academy of Sciences: Synthesis of phylogeny and taxonomy into a comprehensive tree of life

Nat Geo: Exploring Vertebrate Classification