The Animal Kingdom is at once the Kingdom most familiar and least familiar to us. Almost all of the animals we commonly think of -- mammals, fish, and birds -- belong to a single subgroup within one of the 33 Phyla comprising the Animal Kingdom. On the other hand, over 100,000 species in some 25 animal phyla -- mostly small worms -- are so unfamiliar that they are virtually unknown to non-scientists. The same goes for several hundred thousand tiny insect-like species populating the Arthropoda phylum.

All told, around 800,000 species have been identified in the Animal Kingdom -- most of them in the Arthropod phylum i.e. bugs. In fact, some scientists believe that if we were to identify all species in the Tropical Rainforests the ranks of Arthropoda would swell to over 10 million species.

Here are highlights of the larger-sized (and more easily identified) members of the animal kingdom:

Spinal Chords (Chordata)

All animals having a spine including Fish, Mammals, Birds, Reptiles, Amphibians, Sharks, and Eels are grouped into Chordata.

Because these animals are so familiar to us, biologists have come up with elaborate classification schemes including subphyla, superclasses, infraorders, and the like.

The vast majority (including all the Classes listed above) fit into the subphylum Vertebrata -- those having a backbone. Subphyla Agnatha, jawless fish, includes certain eels such as the Lamprey. Cephalochordata and Tunicata round out the list of subphyla with fairly obscure creatures called Lancelets and Tunicates respectively.

All told, this familiar phylum includes 45,000 species of which you are just one.

Joint-Legs (Arthropoda)

If your animal has jointed legs and no spine, you can find it in the Arthropoda phylum. This includes most, if not all, of the animals we commonly call "bugs" as well as the crustacians. 500,000 have already been identified and scientists believe that up to 10,000,000 species alive today.

The classes of this phylum include -- in the order pictured here -- the six-legged Insects (Insecta, such as the stinkbug pictured here); the eight-legged Arachnids (Arachnida) including spiders, scorpions, and ticks; the hard-bodied Crustacians (Crustacea) including Crabs, Shrimp, and Barnacles (Crabs picture here); and Malacostraca which includes the Sowbug or Pillbug.

Other Arthropod classes are: Merostomata -- home of the Horseshoe crab; Millipedes (Diplopoda); and Centipedes (Chilopoda)

Soft Bodies = Mollusks (Mollusca)

Mollusks are so named because of their soft bodies (Greek: mollis = soft). The soft bodies of many of the 110,000 Mollusk species are protected by a hard shell, however. Even those without this protection, such as slugs, still have vestigial traces of a shell.

The Classes are: Polyplacophora with a shell composed of 8 overlapping plates such as the Lined Chiton (Tonicella lineata), above; Gastropoda are slugs and snails including the Banana Slug, above; Bivalvia or Bivalves, such as clams and mussels (above); and Cephalopoda -- octopus and squid, as well as the Nautilus.

Other classes are Monoplacophora, Scaphoda (tooth shells).

Spiny-skinned (Echinodermata)

6,000 species usually found in tide pools. These animals are radially symmetrical -- they have no distinct front and back, only a top and a bottom.

The classes are: Asteroidea -- Starfish such as the Six-rayed Star above (Leptasterias hexactis); Ophiuroidea -- brittle stars; Echinoidea including Sea Urchins (pictured) and Sand Dollars; Holothuroidea -- Sea Cucumbers; and Crinoidea.

[Marine] Stingers (Cnidaria)

9,500 species. Sometimes called Coelenterates.

Familiar names: Jelly Fish, Sea Anemonies (pictured), Corals, Medusas, Hydras. These animals are also radially symmetrical. In addition, they have tentacles with stinging cells.

Sponges (Porifera)

10,000 species. Familiar names: Sponges

Other Phyla containing species which may be familiar to the amateur include: Segmented Worms (Annelida, 8,800 species including the common earthworm and leeches), Lamp shells (Brachiopoda, 350 species), Comb Jellies (Ctenophora, 90 species), Nematodes (Nematoda, 80,000 species) and Horsehair worms (Nematomorpha, 240 species).