Copyright WB Leatham 1996

Cellular Life


Superkingdom Prokaryota

Kingdom Eubacteria

Superkingdom Eukaryota

Kingdom Protoctista

Kingdom Plantae

Kingdom Archaebacteria

Kingdom Fungii

Kingdom Animalia

Descriptive Overview: After many years of trying to find a comprehensive synoptic classification and description of the Earth's biosphere, I decided to create one. This particular version is my own interpretation of the high order systematics that have been developed since Karl von Linne (1758) wrote his original Systema Naturae per Regna Tria Naturae. I have tried to incorporate recent discoveries of new taxa into this system, and have attempted to retain the modified Linnean hierarchal system--Kingdom, Phylum, Class, Order, etc.--as well as attaching the prefices super and sub as required. The taxonomic units of superkingdom are synonymous herein with domain. A few exceptions to the classical Linnean system have been included in this work. Taxonomic subdivisions of the Prokaryota are somewhat problematic, and include several groups of apparently related forms that have similar ecologies, although those exploitive behaviours are probably reflective of genetic homogeneity. Consequently, some of those units are termed "groups", whereas others have been assigned to the rank of phylum. The Plantae have been classically classified into divisions (= phyla), and that practice has been incorporated into this classification scheme. Animalian phyla apparently represent several different organizational grades, or bauplaene, which are included in this system. Within the multicellular kingdoms, i.e. Fungii, Plantae, and Animalia, the phyla are arranged in order of apparently increasing complexity, which may be reflective of their evolutionary development. The arrangement of phyla and groups in single-celled organisms, i.e. Prokaryota and Protoctista, is entirely arbitrary, as systematic relationships for them are problematic at best.



Superkingdom Prokaryota (formerly Monera)

"Before nut". Cells lacking membranated organelles. Typically asexual, but some are capable of genetic recombination by donating or accepting genes. One single loop-like chromosome contains prokaryotic DNA, and some DNA is located in small circular plasmids. Includes all bacteria. Hetero- or autotrophic. Oldest known fossils (3.5 Ga) from stromatolites (laminated mineralized layers typically produced by bacterial colonies) of the Warawoona Group, Australia. Currently the largest source of biomass on Earth, inhabiting both the outer crust and almost all surface environments.

Archaean to Recent

Kingdom Archaebacteria or Archaea

"Primitive small rods". Bacteria that inhabit some of the most hostile bioenvironments on Earth. Studies show that they are about as different from the Eubacteria as plants are from animals. Phyla for bacteria are established through chemistry and metabolism, not morphology which is comparatively simple. Cell wall contains glycoproteins.

Archaean? to Recent

Group Methanogenic bacteria

"Methane-synthesizing" (CH4) bacteria, anaerobic chemotrophs that reduce CO2 using H2 or by anaerobic metabolism of acetate. Often found within the guts of animals. Second most abundant type of archaebacteria.

Archaean? to Recent

Group Halophilic bacteria

"Salt-loving" bacteria that can tolerate high concentrations of potassium. Phototrophic using bacteriorhodopsin as the catalytic pigment, which colors them various shades of red. Least abundant form of archaebacteria.

Archaean? to Recent

Group Thermoacidophilic bacteria

"Temperature- and acid-loving" anaerobic bacteria that require sulfur for metabolism. SH chemotrophic or sulfate-reducing. Most abundant type of archaebacteria.

Archaean? to Recent

Kingdom Eubacteria

"True small rods". Eubacteria are either nutrient absorptive, aerobic, or anaerobic. Phyla for bacteria are tentative and poorly acknowledged. May have cell wall containing peptidoglycan or be "wall-less". Lack of definitive morphology as well as inherently poor preservation prevent determination of actual range through time.

Archaean to Recent

Phylum Aphragmabacteria

"Unwalled small rods". Bacteria that lack cell walls.

Archaean? to Recent

Phylum Spirochaetae

"Twisted or coiled bristle". Spirochetes, similar to sperm cells with long coiled tail. Typically anaerobic (some are aerobic) heterotrophs.

Archaean? to Recent

Phylum Thiopneutes

"Sulfur-breathers". Anaerobic sulfate- or sulfur-reducing bacteria produce H2S.

Archaean? to Recent

Phylum Cyanobacteria

"Blue bacteria". Blue-green algae, photosynthetic, can produce stromatolites.

Archaean to Recent

Phylum Rhizobacteria

"Rooted small rods". Nitrogen-fixing (N2) heterotrophic aerobic bacteria often found in soil.

Archaean? to Recent

Phylum Pseudomonada

"False single units". Oxygen-respiring, non-fermantative bacteria that produce CO2.

Archaean? to Recent

Phylum Omnibacteria

"All bacteria." Typically aerobic or facultative heterotrophs (e.g. Escherichia coli).

Archaean? to Recent

Phylum Chemoautotrophic bacteria

"Chemical self-feeding bacteria". Iron-fixing, ammonia-fixing, or sulfur-oxidizing bacteria.

Archaean? to Recent

Phylum Myxobacteria

"Mucus bacteria". Gliding heterotrophic bacteria that typically produce CO2.

Archaean? to Recent

Phylum "Fermenting bacteria"

Anaerobic, obtain energy through breaking down organic compounds.

Archaean to Recent

Phylum Aeroendospora

"Air-borne inside seeds". Aerobic endospore-forming bacteria (e.g. Bacillus).

Archaean? to Recent

Phylum Micrococci

"Small spheres". Aerobic cocci.

Archaean? to Recent

Phylum Actinobacteria

"Rayed bacteria". Branched or filamentous aerobic bacteria.

Archaean? to Recent

Superkingdom Eukaryota

"With seed". Cells with organelles, DNA is enclosed in nucleus. Both sexual and asexual reproduction.

Proterozoic (1.6 Ga) to Recent

Kingdom Protoctista

"First established". Single-celled with organelles, typically larger than prokaryotes, both sexual and asexual reproduction, many are morphologically complex and some are colonial. Aquatic. Auto- and heterotrophic.

Proterozoic (1.6 Ga) to Recent

Phylum Sarcodina (Rhizopoda and Actinopoda)

"Fleshy or meaty". Ameoboid with pseudopodia for locomotion and/or feeding. Lack plastids and are heterotrophic. Many forms secrete opaline (SiO2.nH2O) or calcareous (CaCO3) shells or tests. Major components of oceanic ooze. Both radiolaria and foraminifera are important components of oceanic oozes. Approximately 48,00 identified species, 2/3 of which are fossil forms.


Phylum Kinetoplasta

"Kinetic shaped-pieces". Eukaryotes with one or two flagellae housed in a pocket. No plastids. Single loop like mitochondrion. About 600 living species.


Phylum Haptophyta

"Plants with a haptonema." Small, photosynthetic nannoplankton, biflagellate with a central filamentous haptonema (touchable thread). Some secrete shield-like plates of CaCO3. Includes the coccolithophorida (predominate components of chalk). Mainly marine. About 450 living and 1100 fossil species.

Triassic to Recent

Phylum Bacillariophyta

"Little stick plants". Photosynthetic freshwater or marine phytoplankton with porous opaline bivalved frustule or shell (e.g. diatoms). Predominate component of diatomite. About 10,000 living and possibly 15,000 fossil species.

Jurassic to Recent

Phylum Rhodophyta

"Red plants". Photosynthetic benthic algae, colored by red plastids. Gelatinous (agar) cell walls, some of which are calcified. Mostly marine. Colonial forms produce coral-like masses of CaCO3, and have a long fossil record. About 4250 living and 750 fossil species.

Cambrian to Recent

Phylum Dinophyta ("Whirling plants") or Pyrrophyta ("Flame-colored plants")

Pyrrophytes have two flagellae, one defines the posterior of the cell and one is helically wrapped in girdle around cell. Action of two flagellae produces whirling motion. Cells are typically armored with celluloid plates forming a theca or shell. Cells contain golden-brown plastids. Includes all dinoflagellates. About 2000 living and 2000 fossil species described.

Silurian to Recent

Phylum Chlorophyta

"Green plants". Photosynthetic green algae, often colonial. Many species are calcareous and produce vast quantities of CaCO3 sediment. About 8000 living and over 500 fossil species.

Cambrian to Recent

Phylum Euglenophyta

"True wonder plants". Photosynthetic soft-bodied cells with a single flagellae and numerous chloroplasts. Some possess eyespots. Mainly freshwater, near abundant organic nutrients. About 1000 living species.

Jurassic to Recent

Phylum Parabasalia

"Close to basal". One or more flagellae located at one end of cell. Lack chloroplasts and mitochondria. Endobiotic. About 2000 living species.


Phylum Opalinata

Flat, endosymbiotic cells with rows of small, undulating flagellae. Lack chloroplasts and live exclusively in the digestive tracts of amphibians and fish. About 400 living species.


Phylum Stephanopogonomorpha

"Crowned with a beard." Cells with rows of thin, small flagellae across surface. Exclusively marine interstitial (between sediment grains). Only a few living species are known.


Phylum Ciliophora

"Eyelash bearer". Spherical to oval cells covered with cilia used for locomotion and/or feeding. Both micro- and macro- nuclei. Marine, fresh-water, terrestrial, or parasitic. Exclusively heterotrophic. Includes the vase-shaped tintinnids. About 7500 living and a over 50 fossil species.

Triassic to Recent

Phylum Apicomplexa

"Top complex". Parasitic eukaryotes, heterotrophic. Several life stages, one of which has an apical complex of unique organelles. Flagellae typically absent. About 500 living species.


Phylum Metamonada

"Changing single units". Cells possess one or two pair of flagellae, one of each pair oriented along axis of cell. Lack plastids and mitochondria. Endobiotic and absorb nutrients through phagotrophy. Some form cysts. Several hundred living species.


Phylum Chrysophyta

"Golden plants". Coccoidal flagellates, commonly with unequal flagellae: one is smooth and the other bears two rows of thick "hairs". Chrysophytes have golden-brown chloroplasts (autotrophic). Includes the silicoflagellates with opaline skeletons, common as fossils in siliceous oozes. About 600 living and 200 (silicoflagellate) fossil species.

Proterozoic to Recent

Phylum Raphidophyta

"Root plants". Biflagellate, similar to Chrysophyta, golden-brown plastids, large nucleus and store abundant oil in vacuoles. About 25 living species.


Phylum Phaeophyta

"Dusky plants". Brown algae, multicellular (colonial), filamentous, or stalked. Some forms to 50 meters (e.g. giant kelp). Photosynthetic with thick mucilaginous cell wall and yellow-brown plastids. Used for food and as a binding and/or gelling additive for materials such as ice cream. About 1500 species and a few possible fossil impressions.

Ordovician? to Recent

Phylum Xanthophyta

"Yellow plants". Similar to a coccoidal chrysophyte with two unequal flagellae, yellow-green plastids, an eyespot, and "bivalved" cell wall. Mainly freshwater. About 650 living species.


Phylum Eustigmatophyta

"Primitive spot bearer". Coccoidal cells similar to the Chrysophyta, with yellow-green plastids, two unequal flagellae, and a single cell wall. Found in soil, and as freshwater and marine plankton. About ten living species.


Phylum Cryptophyta

"Concealed plants". Protoctistids with two parallel flagellae, both of which may be covered with thick "hairs". Cell covered with delicate organic shell. All are photoautotrophs with various types of chloroplasts which produce food reserves of starch. Both marine and freshwater. No known fossils. About 200 living species.


Phylum Chytridiomycota

"Little earthen pot fungus". Parasitic or saprobic heterotrophs with typically coccoidal body and either a flagellum or small, tapering rhizoids extending from one pole. Lack plastids. Body wall is chitinous and/or glucan. About 900 living and several fossil species. "Water molds"

Devonian to Recent

Phylum Choanoflagellata

"Funnel whips". Similar to the collared cells of sponges, these free-living, solitary eukaryotes have a single flagellum surrounded by a collar of small tentacles. Heterotrophic, they sometimes secrete a small, basket like skeleton of opaline bars. About 400 living species.


Phylum Ascetospora

"Curiously wrought seeds". Parasitic to invertebrates, Ascetospora lack flagellae and chloroplasts, possess mitochondria, and produce numerous differentiated spores within their cytoplasm. About 30 living species.


Phylum Myxozoa

"Lamp-nozzle animals". Spore-producing animal parasites with polar capsules containing coiled filaments for anchorage prior to releasing spores. Lack chloroplasts, and flagellae, but contain mitochondria. About 900 living species.


Phylum Microspora

"Small spores". Small, spore-like unicells with a unique hose-like attachment for reproduction. Lack chloroplasts, mitochondria, and flagellae. Intracellular parasites of almost all types of animals and protozoa. About 800 living species.


Phylum Phycomycota

"Slime molds". Similar to fungi, but reproduction is different. Body is branched (rhizae) and reproduction different than all known fungii. About 800 living species.


Phylum Labyrinthomorpha

"Maze forms". Numerous rhizae in hyaline cytoplasm of branched cell, lack chloroplasts, heterotrophic or saprophytic. About 25 living species.


Kingdom Plantae

Plants are typically classified into divisions, not phyla. Multicellular, tissue-grade photosynthetic organisms, vascular system, cells have cellulose cell walls.

Ordovician to Recent

Division Bryophyta

"Moss plants". Liverworts, mosses, and hornworts. Restricted to humid environments. About 23,000 living species and over 150 fossil species.

Late Paleozoic to Recent

Division Psilophyta

"Bare plants". Mainly extinct, lack true roots, small scale-like nerveless leaves, simple stems, and sporangia. Oldest known vascular plants (Silurian). About nine living and over 40 fossil species.

Silurian to Recent

Division Lycopodophyta

"Clubmoss plants". Spore-bearing plant with small leaves helically arranged around stem, Living species are small (e.g. clubmosses), but some fossil forms were very tall and tree-like (e.g. Pennsylvanian Lepidodendron). About 900 living and over 130 fossil species.

Silurian to Recent

Division Sphenophyta

"Wedge plant". " Spore-bearing plants with segmented hollow, silica-impregnated stems, each of which is ringed by a whorl of scale-like leaves. Stems are photosynthetic, Sporangia are apical. Often called "arthrophytes" Living species (e.g. Equisetum or the "horsetail") are small. Extinct forms were tree-like. About 25 living and over 110 fossil species.

Devonian to Recent

Division Filcinophyta

True Ferns. Sporangia (spore-bearing organs) are located on the undersurface of branching leaves. Leaves attached to underground rhizome or massive trunk. About 10,000 living and over 400 fossil species.

Devonian to Recent

Group Pinophyta = "gymnosperms"

Gymnosperms ("naked seeds") are characterized by exposed seeds which may be housed in seed cones. Gymnosperms lack true flowers. Often termed "evergreens". Over 700 living species.

Carboniferous to Recent

Division Cycadophyta (Cycadopsida)

Massive unbranched stems, with feathery pinnate leaves arranged in a spiral near the stem apex. Includes the bush- to tree-size pteridosperms "seed ferns" 1, (e.g. Glossopteris); the primitive cycadeoidea 2; true cycads (Cycadales 3); and the long-leafed, tree-like cordaitophyta (Cordaites 4).

1 Carboniferous to Recent 2 Triassic to Cretaceous 3 Triassic to Recent 4 Carboniferous-Permian

Division Ginkgophyta

Well developed trees characterized by fan-shaped, deciduous leaves with parallel regularly branching veins. Fleshy seed coats. Only one single surviving species, often called "maidenhair trees". Over 60 fossil species.

Triassic to Recent

Division Coniferophyta

"Plants with cone-shaped fruit". Trees and bushes with simple, scale- or needle-like leaves with two vascular bundles and typically waxy, heavy cuticles. Open seed-bearing cones. Over 500 living and 350 fossil species.

Carboniferous to Recent

Division Gnetophyta

Joint firs. Small, tropical climbing trees and bushes, e.g. Ephedra. Striate, ribbed pollen. Over 70 living and two fossil species.

Triassic to Recent

Group "Angiosperms"

Division Magnoliopsida

Angiosperms ("flowering plants") are seed-bearing, pollination and seed dispersal often associated with insect and/or animal transmission. Flower produces fruit and seed-coat protecting the embryo. Includes both monocots (leaves with parallel veins, e.g. grasses, palms) and dicots (leaves with net-like veins, e.g. roses, strawberries). Over 280,000 living and 1000 fossil species.

Cretaceous to Recent

Kingdom Fungii (Mycophyta)

"Mushrooms". Free-living or nutrient absorptive eukaryotes with chitinous and glucan cell walls characterized by hyphae (small branched filaments). Propagate through spores. Includes the yeasts, mushrooms, and molds. Ediacaran "fauna" (850 Ma to 570 Ma) may actually be fungal. Over 60,000 living and about 200 fossil species.

Silurian to Recent

Phylum Zygomycotina

"United fungus". True molds. Includes both saprophytic varieties and arthropodal or protist parasites. About 700 living species.

Pennsylvanian to Recent

Phylum Ascomycota

"Bladder fungus". Sac fungii and yeasts (vegetative phase unicellular); blue, green, and powdery molds; black mildews. Often parasitic to plants. About 29,000 living species.

Late Silurian to Recent

Phylum Basidiomycota

"Pedestal fruit fungus". Club fungi, rusts, smuts, mushrooms and toadstools; puffballs, stinkhorns. About 16,000 living species.

Pennsylvanian to Recent

Phylum Deuteromycotina

"Secondary small fungus". Known as the "Fungi imperfecti"; these fungii possess their asexual or mycelial state. Includes Aspergillus and Penicillum. About 15,000 living species.


Kingdom Animalia

"Lively beings". Multicellular, tissue-grade eukaryotic heterotrophs. Often termed "metazoa". Typically subdivided into superphyletic "grades" by tissue type, developmental stages, and characteristics of the body cavity. Oldest animal fossils are Sinian (650 Ma). Highest species diversity of all kingdoms.

Sinian to Recent

multicellular grade

Multicellular heterotrophs probably lacking true tissues. Parazoa (e.g. sponges) characterized by totipotent cells. No developmental stages indicative of gastrulation. Possibly colonial protoctistids.

Late Proterozoic to Recent

Phylum Placozoa

"Tabular animals". One living species, Trichoplax adhaerens composed of over 1000 ameoboid cells in two layers. Originally discovered in 1883 in Austrian marine aquarium.


Phylum Archeocyatha

"Initial cups". Extinct organisms, either tissue grade or possibly colonial protoctista, secreted a double walled, conical calcareous skeleton held together with septae, tabulations, or dissepiments characterized by numerous pores and an large internal cavity.

Early Cambrian

Phylum Mesozoa

"Middle animals". Ciliated bilaterally symmetrical endoparasites (invertebrate hosts). Two cell layers as in the Placozoa. About 50 living species.


Phylum Porifera

"Pore-bearers". Sponges, perforated with pores to siphon nutrients from water, and supported by a mineralized or durable, spicular skeleton. Mostly marine--about 10,000 living species, of which only 150 inhabit freshwater. About 2400 fossil species.

Late Proterozoic to Recent

diploblastic grade

"Two germs or tissues". Both endodermal and ectodermal tissue separated by the jelly-like mesoglea. No mesodermal tissue.

Phylum Cnidaria

From the Greek word for "nettle". Radial to biradially symmetrical diploblasts possessing cnidae (whip-like stinging cells). Some forms secrete mineralized skeletons. Includes the jellyfish, corals, anemones, and hydroids. Solitary or colonial, benthic or plankto-nektonic. Over 10,000 living species, mostly marine except for a few freshwater hydroids. About 9300 fossil species described.

Later Proterozoic to Recent

Phylum Ctenophora

"Comb-bearer". Comb jellies and sea gooseberries. Biradial symmetry with rows of cilia Major class typically has two tentacles. No true cnidae. Plankto-nektonic. About 100 living species, exclusively marine.

Devonian to Recent

triploblastic grade

"Three germs or tissues". Ecto-, endo-, and mesodermal tissue. Some forms metamerous. Body cavity (coelom) may develop in certain forms within mesoderm, and usually contains various organs.

acoelomate triploblastic grade

Acoelomate = "without body cavity". Animals that have mesodermal tissue between their gut and body wall.

Phylum Platyhelminthes

"Flat worms". Bilaterally symmetrical, lack true body cavity, organs are encased in mesoderm. Distinctive head. All are free-living, feeding on animal tissue, and many are parasites, scavengers, or carnivores. Usually hermaphroditic. About 25,000 living species, and a few, rare fossils.

Late Proterozoic to Recent

Phylum Nemertea

"Sea nymph". Worm-like (vermiform), acoelomate animals with both a mouth and anus, and a characteristic eversible proboscis housed in a tubular cavity that is used to capture prey. Some species are very long, (over 40 meters). Most are benthic marine. About 900 living and several fossil species.

Carboniferous to Recent

Phylum Gnathostomula

"Jaw mouth". Small, bilaterally symmetrical, worm-like acoelomates. Hermaphroditic. Paired jaws (gnathae) surround the well developed pharynx. Typically interstitial and benthic marine. About 100 living species.


Phylum Gastrotricha

"Stomach hairs". Small, bilaterally symmetrical, acoelomate vermiform aquatic animals characterized by a dorso-ventrally flattened body with a distinctive tail. Body covered with small scales, spines or hooks, and adhesive tubes for attachment. Mostly hermaphroditic. About 450 living species.


pseudocoelomate triploblasts

Pseudocoelomate = "false cavity". Animals with a fluid-filled body cavity between the gut and the mesoderm that may contain organs.

Phylum Rotifera

"Wheel-bearers". Small, bilaterally symmetrical aquatic animals, cone-shaped, spherical, or elongate with a characteristic, anterior crown of cilia (corona). Mostly freshwater. About 1800 living species.


Phylum Kinorhyncha

"Kinetic snout". Small, bilaterally symmetrical, vermiform marine animals with an apparent external and no discernible internal segmentation. Pseudocoelomic. Body externally divisible into 13 segments, two of which define the head. The head is eversible with a terminal mouth cone. Body covered with chitinous cuticle and small spines used to burrow. Multi-lobed brain and ventral nervous system. About 100 living species.


Phylum Nematoda

"Thread-like". Unsegmented, pseudocoelomic, round worms with tapering ends. They inhabit virtually all habitats, including muscular tissues. Usually small, but may be up to 8 m in length. About 15000 living species, although some experts estimate that over 1,000,000 species exist.

Carboniferous to Recent

Phylum Nematomorpha

"Thread shapes". Similar to the Nematoda in body plan, but the alimentary canal in adults is essentially non functional. Fine bristles or setae aligned along body. Nematomorphs are parasitic in arthropods as juveniles in insects or marine crustaceans and free-living as adults. About 250 living species.


Phylum Acanthocephala

"Prickly heads". Parasitic, vermiform psuedocoelomic animals characterized by stiff, sclerotized hooks surrounding a retractable muscular proboscis used to anchor the worm to the intestines of vertebrates and invertebrates. About 1000 living species.


Phylum Loricifera

"Corset-bearer." Small, bilaterally symmetrical or biradial pseudocoelomate interstitial meiofaunal organism with distinct head, neck and thorax. Cone-like mouth surrounded by spiny appendages. Test is composed of organic plates. Over thirty living species.


Phylum Priapula

Name derived from Priapos, the Greek god of reproduction symbolized by priapus or "penis". Small to large, free-living vermiform marine animals. Two to three distinctive regions recognizable on stubby cylindrical bodies with a well developed body cavity. Characterized by an retractable, barrel-shaped proboscis used for feeding and locomotion, surrounded small spines, papillae, or tentacles. Trunk is typically annulated with warty bumps or spines. Body covered with moultable chitinous cuticle. Active carnivores. About ten living and at least one fossil species.

Cambrian to Recent

coelomate triploblastic grade

Coelomate = "With a body cavity". Animals with one or more true body cavities surrounded by mesoderm.

Phylum Sipuncula

"Little tubes". Vermiform, coelomic unsegmented worms with plump posterior and necked anterior. Neck extends by hydrostatic pressure, and retracts with one to four muscles. Mouth surrounded by ring of ciliated, hydrostatic tentacles. U-shaped gut. About 350 living species.

Devonian? to Recent

Phylum Echiura

"Viper". Plump-bodied, coelomic unsegmented worms with a long, coiled gut terminating in posterior anus. Characterized by an extendible proboscis or cephalic lobe with a ventrally located ciliated groove for food gathering and gaseous exchange. Benthic marine deposit-feeders. About 150 living species.

Cambrian? to Recent

Phylum Pogonophora

"Beard-bearers". Long slender, benthic tube-dwelling worms lacking mouth or gut. Oligomerous, with closed hemoglobin system. Adsorbtion of nutrients. Typically deep marine, one order a significant component of hydrothermal vent environments. Over 100 living species and a few fossil tubes have been discovered in obducted crust.

Oligocene to Recent

Phylum Conularida

"Conical entities". Extinct, probably triploblastic sessile animals with a four-sided, pyramidal phosphatic shell with a square or rectangular cross-section constructed of intermeshed phosphatic rods. About 25 genera.

Cambrian to Triassic

Phylum Mollusca

"Soft". Pseudometamerous, soft-bodied organisms covered with a thin epidermis or mantle. Molluscan body plans are modifications of this central theme. Molluscan morphology typically consists of a distinctive head with mouth and/or tentacles, a large ventral foot, a dorsal visceral hump, and a radular mouth. Most species secrete an external calcareous shell (aragonite), which is typically coiled. or composed of multiple parts. Characteristically divided into groups based on the type of shell: Diasoma, Cyrtosoma, and Polyplacophora. Over 50,000 living and over 41,000 fossil species.

Cambrian to Recent

Class Monoplacophora

"Single plate-bearer". Small, bilaterally symmetrical mollusc with a single cap-shaped shell supported by paired muscles. Only one family of living monoplacophorans have been identified, and many workers assign the symmetrically coiled bellerophontid gastropods to this class. About eight living species and over 25 fossil genera.

Cambrian to Recent

Class Chaetodermorpha

"Bristled skin forms". Burrowing, scaled mainly vermiform mollusks. Only one living order and no apparent fossil record.


Class Neomeniomorpha

Vermiform, laterally compressed mollusks that often are associated with and eat Cnidaria. Over 21 living species with no apparent fossil record.


Class Polyplacophora

"Bearer of multiple plates". Dorso-ventrally compressed, ovoid bilaterally symmetrical mollusks characterized by a strong muscular foot and eight overlapping dorsal calcareous plates. Includes the "chitons". Over 600 living species assigned to 14 families and over 75 fossil genera.

Late Cambrian to Recent

Class Gastropoda

"Stomach foot". Asymmetrically coiled (torted) mollusks with at u-shaped gut and nervous system. Characterized by a single helically coiled shell (Cyrtosoma), although some forms have lost their shell. Includes snails and slugs. Marine, freshwater, and terrestrial (the only terrestrial mollusks). Over 69,000 living and 21,000 fossil species.

Cambrian to Recent

Class Scaphopoda

"Scoop foot". Elongate tubular shell open at both ends, benthic marine. Often termed tusk shells. Over 350 living and six fossil genera.

Ordovician to Recent

Class Bivalvia (Lamellibranchiata or Pelecypoda)

"Two folding doors". Shell consists of two lateral valves (i.e. Diasoma), connected with a tough ligament and toothed hinge. Laminar gills (i.e. Lamellibranchiata) and laterally compressed foot (i.e. Pelecypoda or "hatchet foot"). Usually marine or freshwater benthic, but some are facultative nekton. Over 11,000 living and 16,000 fossil species.

Cambrian to Recent

Class Cephalopoda

"Head foot". Characterized by single, bilaterally coiled, internally septate shells (i.e. Cyrtosoma), which in some forms are reduced or lost. Chambers connected by wick-like siphuncle. Body tentaculate, complex eyes and a beak-like radula and mouth. Includes the octopods, squid, nautiloids, and ammonoids, and belemnoids. The ammonoids and belemnoids are wholly extinct, and living nautiloid diversity is limited to under ten species. Over 300 living and 17,000 fossil species.

Late Cambrian to Recent

Class Rostroconchia

"Snout shell". Extinct bivalve-like mollusk with dorsally fused valves. About 40 fossil genera.

Early Cambrian to Late Permian

Phylum Hyolitha

Extinct mollusk-like organism characterized by a dorso-ventrally compressed conoidal calcareous shell, with a flap-like operculum and two wing-like appendages (helens). About 40 fossil genera.

Early Cambrian to Late Permian

metamerous coelomate triploblastic grade

Metamerous = "Between or among segments". Coelomate = "hollow cavity". Segmented animals with true body cavities.

Phylum Annelida

"Annulated or ringed". Segmented bilaterally symmetrical worms. Metamerous coelomates, with paired chitinous setae in each segment. Segments separated externally by annular furrows. Distinct head and pygidium (tail). Three distinct classes: Hirudinoidea (leeches), Oligochaeta (earthworms), and Polychaeta (bristled marine annelids). Over 15,000 living and over 150 fossil species.

Proterozoic? to Recent

Superphylum Arthropoda

"Jointed foot". Metamerous (segmented) bilaterally coelomate animals with a chitinous exoskeleton.

Cambrian to Recent

Phylum Crustacea

"Hard outer rind or shell". Body typically divisible into a head, thorax, and abdomen, although in some forms the head and thorax are apparently fused. Exoskeleton usually calcified. Appendages are typically biramous or branched. Includes Ostracoda (small, calcified bivalved carapaces) , Branchiopoda (e.g. fairy or brine shrimp and clam shrimp), Copepoda, Cirripedia (barnacles), Isopoda (pill or sow bugs) and Malacostraca (shrimp and crabs). About 39,000 living species and over 2700 fossil genera.

Cambrian to Recent

Phylum Chelicerata

"Claw-bearers". Two basic body segments: a prosoma with the head and anterior appendages, and an opisthosoma (with a tail-like telson). Characterized by prominent preoral appendages near mouth, which may be chelate (pincers) or act as seminal organs (pedipalps). Includes horseshoe crabs (i.e. Xiphosura), the extinct eurypterids, and the ticks and spiders (Arachnida)., and the marine Pycnogonida (sea-spiders) About 63,000 living and over 400 fossil genera.

Possibly Cambrian but definitely Ordovician to Recent

Phylum Trilobitomorpha

"Three-lobed forms". Dorsal surface divided into three longitudinal lobes: two pleural and one axial. Body with biramous limbs and separated into a distinct cephalon (head), thorax, and pygidium (tail). Extinct, marine habitats. Over 20,000 fossil species.

Cambrian to Late Permian

Phylum Onychophora

"Talon-bearers". Free-living vermiform organisms with paired biramous appendages along body and a pair of both annular antennae and claw-like mandibles. Features of both annelids and arthropods. About 70 living, predominantly terrestrial species, and a couple of Cambrian marine and several Pennsylvanian terrestrial species.

Cambrian to Recent

Phylum Tardigrada

"Slow-stepper". Small (<1 mm), free-living apparently multisegmented, pseudocoelomate, squat-bodied, with four pairs or short, unsegmented legs. Interstitial habitats and water films. Enigmatic relations. Often termed "water bears". About 400 living and one Cretaceous species.

Cretaceous to Recent

Phylum Pentastoma

"Five mouths". Apparently segmented, annular, elongate vermiform parasites with a five-lobed head (anteriormost lobe terminates in jawless mouth flanked by two pairs of hook bearing leg-like lobes). About 100 living species.


Phylum Uniramia

"Single branches". Bilaterally symmetrical, segmented (metamerous) animals with single branched (uniramous) jointed appendages. Includes the Hexapoda (insects) 1, Myriapoda (millipedes) 2, and Chilopoda (centipedes) 3. More than 1,000,000 living species and over 5000 fossil genera.

Silurian to Recent 1 Middle Devonian to Recent 2 Silurian to Recent 3 Cretaceous to Recent

oligomerous triploblastic grade

Oligomerous = "few divisions". Triploblasts with several body cavities of unequal size

Superphylum Lophophorata

"Crest-bearers". Bilaterally symmetrical unsegmented coelomate animals characterized by an anterior, tentacled food gathering organ (i.e. lophophore). Aquatic benthic sessile suspension feeders.

Cambrian to Recent

Phylum Phorona

Bilaterally symmetrical worm-like creatures characterized by a u-shaped terminal lophophore, and a u-shaped gut with anus terminating outside the lophophore. Name is based on Zeus' mistress who was transformed from human to cow--phoronids have a dual life cycle. About ten living species.

Devonian? to Recent

Phylum Brachiopoda

"Arm foot". Bivalved lophophorates. Two classes, distinguished by shell composition, shell articulation, and gut characteristics. About 350 living and over 25.000 fossil species.

Cambrian to Recent

Class Articulata

Calcium carbonate shells, inequivalved with tooth and socket articulation. Dorsal valve with lophophore support (brachial valve) and ventral valve with opening (foramen) for pedicle (pedicle valve). Gut blind, with no anus. Abundant component of Paleozoic marine faunas. Over 1600 fossil genera.

Cambrian to Recent

Class Inarticulata

Calcium phosphate or calcium carbonate shells, apparently identical, Through gut with anus. Over 130 fossil genera.

Cambrian to Recent

Phylum Bryozoa

Also referred to as "moss animals", these lophophorates are colonial, consisting of small individual zooids which build a gelatinous, polysaccharoidal, or calcareous shell. Zooids are typically polymorphic. Each zooid has an anus that terminates outside the lophophore. About 5000 living and 17,500 fossil species.

Ordovician to Recent

Phylum Entoprocta

"Inside the anus". Unmineralized small lophophorates with an anus that terminates inside the u-shaped lophophore. Mostly marine. About 150 living and no fossil species.


Phylum Cycliophora

"Carrying a small wheel". Small symbiotic organism with a lophophore-like ring of cilia surrounding the mouth. Posterior attachment disk and a complex life cycle of three basic phases: male, female, and asexual. The singular species (Symbion pandora) is found around the mouths of lobsters. Named in 1995.


Phylum Chaetognatha

"Bristle jaws". The bristle or arrow worms. Oligomerous, bilaterally symmetrical animals with a distinct head, trunk and tail. Head has two rows of movable grasping spines, used to capture food. Mostly planktonic. About 70 living and a couple of fossil species.

Cambrian to Recent

Phylum Hemichordata

"Half chordate". Bilaterally symmetrical, vermiform, unsegmented benthic marine animals with up to two body cavities. Includes the Enteropneusta (acorn worms), the pterobranchs, and the extinct Graptolithina 1 (graptolites). About 100 living and over 1800 extinct species.

Cambrian to Recent

1. Late Cambrian to Pennsylvanian

Phylum Echinodermata

"Spiny skin". Usually a pentamerous overprint on a bilateral symmetry, Echinoderms are solitary, characterized by a subepidermal skeleton consisting of calcareous plates or spicules. Body contains a unique water-vascular system terminating in tube-feet. Marine benthic, with long fossil history. Includes the Crinoidea (sea lilies) 1, Asteroidea (starfish) 2, Ophiuroidea (brittle stars) 2, holothurians (sea cucumbers) 1, Echinoidea (sea urchins and sand dollars) 3, helicoplacoids (extinct) 4, edrioasteroids (extinct) 5, blastoids and cystoids (extinct) 6, and homalozoa and carpoids (extinct) 7. About 6000 living and 15,000 fossil species.

Cambrian to Recent

1. Middle Cambrian to Recent

2. Early Ordovician to Recent

3. Late Ordovician to Recent

4. Early Cambrian

5. Early Cambrian to Pennsylvanian

6. Early Cambrian to Permian

7. Middle Cambrian to Middle Devonian

Phylum Conodonta

"Conical tooth". Extinct, bilaterally symmetrical vermiform animals characterized by paired assemblages of phosphatic jaw-like elements, which are common fossils in marine Paleozoic and early Mesozoic rocks. Possibly related to primitive vertebrates or chaetognaths. 4000 fossil species assigned to 220 fossil genera.

Cambrian to Late Triassic

Phylum Chordata

"Characterized by a rope or cord". Solitary, bilaterally symmetrical oligomerous coelomates with a dorsal nerve cord and dorsal internal skeletal rod (notochord). Includes the Urochordata (tunicates, sea squirts, and salps) the Cephalochordata (Amphioxus or lancets) 1, and the Vertebrata (humans through dinosaurs). Classes of the Vertebrata include the Agnatha (lampreys) 2, Chondrichthyes (sharks and rays) 3, Osteichthyes (bony fish) 4, Amphibia (frogs, salamanders) 5, Reptilia (dinosaurs, lizards, snakes, turtles, crocodiles) 6, Aves (birds) 7, and Mammalia (cows, aardvarks, humans, platypus) 8. About 40,000 living and 25,000 fossil species.

1 Middle Cambrian to Recent

2 Late Cambrian to Recent

3 Devonian to Recent

4 Devonian to Recent

5 Late Devonian to Recent

6 Pennsylvanian to Recent

7 Jurassic to Recent

8 Triassic to Recent



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