Classification Notes

Classification Notes

Classifying organisms is called taxonomy

Organisms are classified based on characteristics

  • Structure (how built)
  • Function (how do things)
  • Biochemical behavior (chemistry)
  • Nutritional Needs (what it eats)
  • Development (growth)
  • Genetic Structure (DNA)
  • Molecular makeup (what made of)

Aristotle developed the first classification system for living organisms

Carolus Linnaeus developed the modern day classification system

Taxonomy is a system of classification.  Classification divides organisms into groups.  The most general group is domain and the most specific group is species.

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Mnemonic device to remember in order:  Dear King Phillip’s Class Ordered Five Giant Steaks

Genus and Species are a part of the scientific name.  This is called the binomial nomenclature.

Genus is capitalized and listed first and species is lower case and listed second.  The name should be written in italics.

Human Classification Breakdown

Domain-  Eukarya

Kingdom-  Animal

Phylum-  Chordata

Class-  Mammalia

Order-  Primates

Family-  Hominidae

Genus-  Homo

Species-  sapiens

Homo sapiens is the binomial nomenclature for Humans

Carl Woese developed the three Domain system

The Three Domains are: Archaea, Bacteria, and Eukarya.  

The Three Domain System groups organisms primarily based on differences in ribosomal RNA structure. Ribosomal RNA is a molecular building block for ribosomes.

RNA stands for ribonucleic acid which is a nucleic acid that plays an important role in the production of proteins.

Ribosomes are: tiny structures in the cytoplasm of a cell where proteins are made.

Prokaryotes are: organisms whose cells lack a nucleus and some other cell structures

Eukaryotes are: organisms with cells that contain nuclei and other cell structures

An Autotroph can make its own food

A Heterotroph cannot make its own food

A species is a group of similar looking organisms that can mate with each other and can reproduce fertile offspring.  A mule is not a species because they are born sterile and therefore cannot reproduce.

A vertebrate is: an animal with a backbone 

An invertebrate is: an animal without a backbone

Carnivores eat: meat

Herbivores eat: plants

Omnivores eat: both meat and plants

Important animal groups (phyla) are:  cnidarians, mollusks, annelids, arthropods, echinoderms, and chordates

Four important plant groups are:  mosses, ferns, conifers, and flowering plants


At some point in their lives they have a notochord, a nerve cord, and slits in their throat area

The five main groups are: fish, mammals, birds, amphibians, reptiles

Examples include: trout, sharks, whales, cows, cardinals, hawks, frogs, snakes

Symmetry is having balanced portions

The two types of symmetry are

1. bilateral –split in two, mirror images.  Butterflies

2. radial–lines of symmetry that go from a central part.  Sea anemones

Major Animal Phyla are:
For invertebrates:


Invertebrates that have stinging cells and take their food into a hollow central cavity

Examples include: jellyfish, anemones, hydras, coral reefs-are built by cnidarians


Invertebrates with soft, un-segmented bodies that are often protected by hard outer shells and have a thin layer of tissue called a mantle, which covers their internal organs 

Three main groups: gastropods, bivalves, and cephalopods

Examples include: snails, slugs, clam, oysters octopus and nautiluses 


Invertebrates, and they all have long, narrow bodies without legs and have head and tail ends 

The three types are: flatworms, roundworms, and segmented worms


Invertebrates that has an external skeleton, a segmented body, and jointed attachments called appendages

Five main groups: crustaceans, arachnids, centipedes, millipedes, and insects

Examples include: crab, crayfish, shrimp, spiders, scorpions, ticks, grasshopper, butterfly, bee


Invertebrates that have Five-part radial symmetry and an endoskeleton, echinoderms also have an internal fluid system called a water vascular system

Examples include:  sea stars, sea cucumbers, sea urchins, sand dollars, brittle stars

For vertebrates


Description: aquatic vertebrates with scales, fins, and gills

3 Main groups: Bony Fishes, cartilaginous fish, (lobe-finned fishes) lamprey’s and hagfish

Examples: tuna, trout, bass; sharks, rays; northern lamprey


Description: vertebrates that mainly live on land and are endothermic

3 Main groups: placental mammals, monotremes, marsupials

Examples: humans, whales, horses; koalas, kangaroo; platypus, echidna


Description: vertebrates have feathers, wings, bills/beaks, and most can fly

30 Main groups (only pick 3): birds of prey, perching birds, penguins

Examples: eagles, hawks; crow, wren; macaroni penguin, rock-hopper penguin


Description: vertebrates, go from water to land

3 Main groups: newts/salamanders, frogs/toads, caecilians

Examples: mole salamander, mudpuppies; Goliath frog, Eastern American Toad; beaked caecilians, fish caecilians


Description: vertebrates, 4 legs, have scales and amniotic eggs

4 Main groups: crocodilians, squamates, tuatara, turtles

Examples: alligators, crocodiles; collard lizard, geckos; 2 species of tuatara; green turtle, snapping turtle

Examples of Archaebacteria include: Methanobrevibacter smithii, Halobacterium salinarum, Thermococcus litoralis,  and Thermoplasma

Examples of Eubacteria include: Escherichia coli (E. coli), Streptococcus pneumoniae, Salmonella enterica, Yersinia pestis, and Clostridium tetani

Endothermic animals- generate their own heat to maintain their body temperature, body temp remains constant and are commonly referred to as "warm-blooded." An animal that is endothermic is categorized as an endotherm.

Exothermic animal is one who cannot regulate its own body temperature, so its body temperature fluctuates according to its surroundings. Exothermic animals, or exotherms, are commonly referred to as "cold-blooded." Examples of exotherms are: reptiles, amphibians, and fish.

Major Plant groups/divisions/phyla are

Nonvascular and Vascular

A nonvascular plant is a low-growing plant that lacks vascular tissue.

A vascular plant is a plant that has vascular tissue.

Nonvascular plants

Examples include: mosses, liverworts and hornworts


Are vascular and reproduce through spores

Examples include: Ferns, club mosses, and horsetails 


Are seed plants, also called gymnosperms

Examples include: spruce, pine, hemlock

Flowering Plants

Are seed plants, also called angiosperms

Examples include-grasses, lilies, apple trees and maple trees

In the sporophyte stage in the life cycle of a plant, the plant produces spores for reproduction.

In the gametophyte stage in the life cycle of a plant, the plant produces gametes, or sex cells (sperm or egg).














Pro or Euk

(cell type)







Auto or Hetero



Can be both


Can be both


Can be both







Uni or Multi

(#of cells)




some are uni

Multicellular, some are uni