The Entire Animal Kingdom

Have you ever wondered how all of the animals in the animal kingdom are organized? Well, I did once, so I wrote it all down. I just found this in my “personal” folder at work. After reading this, it is clear I might have OCD. The details at each organizational level are limited to principal characteristics of that level (in layman’s terms for the most part), then further subclassification is provided in mostly just the lineages that lead to humans. Sorry all you fish lovers out there, I know this is kind of anthro-centric, but this would be a million miles long if every lineage was included out to the families. This is already ridiculous. So enjoy! You should be able to find your favorite animal somewhere in here. Although perhaps not the popular cat-frog hybrid shown above right. (Note the heading styles have to reset themselves a couple times for the multiple levels of organization.)

**Note: when I assembled this information long long ago, this was pre-genomics revolution. Genetic studies have significantly impacted the taxonomy of animals, so there are several “newer” phyla not represented here. One day I will attempt to update and correct this post accordingly. Don’t hold your breath though.

Kingdom Animalia:

• Multicellular eukaryotes that characteristically ingest their food.

• Cells are usually flexible

• Except in sponges, cells are organized in tissues

• Cells move during embryonic development forming a blastula (hollow sphere of cells)

• Most animals reproduce sexually

• Gametes (sperm and egg) fuse to form a zygote, and do not divide by mitosis (as happens in plants)

Subkingdom Parazoa:

• Animals that lack definite symmetry, no tissues or organs

Phylum Porifera:

• Sponges

Subkingdom Eumatozoa:

• Animals with definite symmetry (radial or bilateral), definite tissues and organs

Phylum Cnidaria: 10,000+ species

• Coral, Jellyfish, Hydra

• Radial symmetry

• Two body forms (polyps and medusae)

• Digestive cavity with only one opening (things go in and out the same hole)

• Stinging cells are unique to this phylum

Phylum Ctenophora: 90 species

• Comb jellies and sea walnuts

• Radial symmetry

• Digestive cavity with an anal pore

Phylum Platyhelminthes: 13,000 species

• Flatworms

• Bilateral symmetry

• No circulatory system

• One-opening guts

• Hermaphroditic

Phylum Nematoda: 500,000 species

• Nematodes, Eelworms, Roundworms

• Bilaterally symmetrical and unsegmented worms

Phylum Mollusca: 110,000 species

• Snails, Slugs, Clams, Octopuses, Squids, Nautilus

• Bilateral symmetry

• Coelomate animals (containing body cavities)

• Visceral mass and muscular foot

Phylum Annelida: 12,000 species

• Earthworms, Leeches

• Segmented, bilaterally symmetrical, protostome coelomates

• Segments are divided internally by septa

• Brain is developed

• Closed circulatory system

• One-way digestive system

Phylum Arthropoda: ~1,000,000 species

• Bilaterally symmetrical protostome coelomates

• Segmental body, chitinous exoskeleton

• Digestive tract, Brain and paired nerve cord, Jointed appendages

Class Arachnida:

• Spiders, ticks, mites, scorpions

Class Crustacea

• Lobsters, crayfish, crabs, shrimps

Class Chilopoda

• Centipedes

Class Diplopoda

• Millipedes

Class Insecta

• Complex mouth parts, three part body, six legs, trachea

Phylum Echinodermata: 6,000 species

• Sea stars, brittle stars, sand dollars, sea cucumbers, sea urchins

• Deuterostome coelomates

• Radially symmetrical

Phylum Chordata: 45,000 species

• Bilaterally symmetrical

• Deuterostome coelomates

• Notochord is present at some point of development

• Pharyngeal slits, hollow nerve cord on dorsal side, and a tail

Subphylum Urochordata: 1,250 species

• Tunicates, marine chordates that have notochord only in larval stage

• Get food by ciliary action

Subphylum Cephalocordata: 23 species

• Lancelets, permanent notochord, nerve cord, no internal skeleton, food by ciliary action

Subphylum Vertebrata: 43,700 species

• Notochord is replaced by cartilage or bone (backbone)

• Distinct head with skull and brain

Class Agnatha: 63 species

• Lampreys and Hagfishes

• Cartilaginous fishes, no jaw

• Parasitic

Class Chondrichthyes: 850 species

• Sharks, skates and rays

• Cartilaginous fishes, sex organs present

• Small pointy scales (denticles), no air bladders

Class Ostheichtyes: 18,000 species

• Bony fishes

• Bony skeletons, efficient fins and scales

• Most have air bladders (regulate density to regulate depth)

Class Amphibia: 2,800 species

• Salamanders, frogs and toads

• Tetrapod, egg-laying, ectothermic

• Gills as larvae, lungs as adults

• Incomplete double circulation (non-closed ventricular system)

Class Reptilia: 6,000 species

• Lizards, snakes, turtles, crocodiles

• Tetrapod, ectotherm vertebrates with an amniotic egg

• Lungs, covered with scales

• Incomplete double circulation

• Four legs are absent in snakes and some lizards

Class Aves: 9,000 species

• Birds

• Tetrapod, endothermic vertebrates

• Forelimbs modified into wings

• Amniotic eggs

• Lungs, complete double circulation

Class Mammalia: 4,500 species

• Tetrapod, endothermic vertebrates

• Complete double circulation, often hairy skins

• Monotremes: Lay eggs (Platypus)

• Marsupials: Retain young in a marsupium

• Placental mammals: Nourish young in the womb by way of a placenta (modification of amniotic egg)

Order Insectivora

• Shrews, Moles, Hedgehogs

Order Chiroptera

• Bats

Order Rodentia

• Squirrels, Rats, Mice

Order Carnivora

• Dogs, Cats, Bears, Weasels, Raccoons

Order Proboscidea

• Elephants

Order Cetacea

• Whales

Order Primata:

Suborder Prosimii

• Lemurs

Suborder Anthropoidea:

Infraorder Platyrrhini

• New world monkeys (South and Central America)

Infraorder Catarrhini

• All other monkeys and humans

Superfamily Cercopithecoidia

• Old world monkeys (Africa and Asia)

Superfamily Hominoidia:

• Family Hylobatidae (Gibbons)

• Family Pongidae (Orangs, Gorillas, Chimps, Bonobos)

• Family Hominidae (Humans)