Classification

and Nomenclatu

re

Taxonomy- the branch of science concerned with classification, especially of organisms; systematics.

2 IMPORTANT SUBDIVISIONS

Classification- arrangement of the kinds of animas in a hierarchy of smaller and larger groups.

Nomenclature- procedure of assigning names to the kind and groups of animals to be classified.

PURPOSE OF CLASSIFICATION

for convenience to show relationships based on phylogeny. distinguish characters that show homology from those that exhibit analogy.

HISTORICAL BACKGROUND(History of Classification)

• Aristotle- considered as the “Father of Zoology”.-He proposed a way of classifying animals as follows:

1. Enaima (vertebrates), with red blooda. Viviparous

1. Humans 2. Whales 3. other mammalsb. Oviparous

1. Birds 2. Amphibians and most reptiles 3. snakes 4. fishes

2. Anaima (invertebrates), no red bloodb. Cephalopods b. crustaceans c. insects, spiders, etc.d. other mollusks, echinoderms, etc. e. sponges, cnidarians,

etc.

John Ray (1627-1705)- the first biologist to have a modern concept of species and to make some efforts to classify a few groups.

Carolus Linnaeus (1707-1778)- laid the real basis for modern classification and nomenclature. -He first introduced the two-kingdom classification which composed of:• Plants- photosynthetic and generally nonmotile• Animals- heterotrophs and generally motile

-In his Systema naturae, he recognized six “classes” of animal kingdom namely:• Mammalia, Aves, Amphibia, Pisces, Insects, and Vermes

Hogg (1860) and Ernst Haeckel (1866) formulated the three-kingdom classification namely:• Protoctista- all of the “problematic groups”, single- celled

organisms.• Plantae (metaphyta)• Animalia(metazoa)

H. F. Copeland proposed a four-kingdom classification which includes:• Mychota- bacteria and blue-green algae• Protoctista- protozoans, fungi, all nucleate algae except

green algae• Animalia• Plantae

Cuvier (1769-1832)- divided the animals into four branches: Vertebrata, Mollusca, Articulata, and Radiata in 1829.

Another four-kingdom classification was proposed by R. H. Wittaker which composed of:• Monera- unicellular organisms without nuclei• Protista- unicellular organisms with nuclei• Animalia•Plantae

Revision of this classification by Wittaker led to the five-kingdom classification which is commonly use today consisting of:

Plantae- photosynthetic and generally nonmotile

Animalia- heterotrophs and generally motile

Fungi- plant like organism but lack green pigment needed for photosynthesis

Moneran - unicellular organisms without nuclei

Protista -unicellular organisms with nuclei

In 1977, an epoch-making discovery was made in the area of bacterial taxonomy that served as foundation of recasting the alignment of taxa in the eukaryotic kingdoms. This resulted to living world being sorted into three supertaxa: the Archaebacteria, Eubacteria and Eukarya. The term “urkingdom” was originally applied to the new taxa.

Prof. Carl Whoese introduced the term “domain” and renamed the three major taxa:•Bacteria- Unicellular organisms-- Prokaryotic, may be photosynthetic, chemosynthetic, or feed by absorption

• Archea- These bacteria-like organisms posses a differing cell wall composition that allows them to survive extreme conditions such as salt lakes, or hot acidic spring

• Eukarya- This domain includes all living organisms that are composed of one or more Eukaryotic cells

The proposal of this three domains led to the formation of the “six-kingdom” and “eight-kingdom” system.

The six-kingdom system

Domain Bacteria-Kingdom Eubacteria/Bacteria

Domain Archaea- Kingdom Archaebacteria�

Domain Eukarya-Kingdom Protista-- Most are unicellular, eukaryotic, may be photosynthetic, may feed by absorption, or may ingest food.-Kingdom Fungi-- Most multicellular although Some are unicellular. Eukaryotic cell structure, absorptive heterotrophs, non motile.-Kingdom Plantae– Multicellular, eukaryotic, photosynthetic, non motile.-Kingdom Animalia-- Multicellular, eukaryotic, ingestive � �heterotrophs, motile, nervous system present�

THE EIGHT-KINGDOM SYSTEM

Domain Bacteria-Kingdom Eubacteria– consists typical bacteria such as spirochetes, chlamydias, gram-positive bactrei, cyanobacteria and proteobacteria.

Domain Archea-Kingdom Archeabacteria-- consists of three main groups of archaic bacteria namely: methanogens, extreme thermophiles and extreme halophiles.

Domain Eukarya-Kingdom Achezoa– includes organisms which were once considered as protozoans but have lost their mitochondria and Golgi apparatus after having adopted a parasitic way of life.

-Kingdom Protoctista– includes organisms that are commonly treated as “protozoans” in conventional zoological classification.

-Kingdom Chromista– composed of eukaryotes with “unusual chloroplasts that have two additional membranes outside the unusual chloroplast envelops a small cytoplasm and vestigial nucleus.

-Kingdom Plantae– eukaryotes which possess chlorophyll a and b, in contrast to those which contain chlorophyll c or d, in addition to chlorophyll a.

-Kingdom Animalia– organisms that are basically phagothrophs. However, many of them are parasitic.

Ernst Haeckel (1864), and E. Ray Lankester (1877)- outlined the principal features of the zoologic classification that is used today.

SPECIES- THE BASIC UNIT in biological classification.-The group of individual which is naturally reproductively isolated from other such group.--they are derived from common ancestry and can breed with one another to produce fertile offspring that resembles the parents.

TAXONOMIC HIERARCHY/CATEGORIES

-Domain-Kingdom-Phylum-Class-Oder-Family-Genus-SpeciesMonotypic- where a group contains only one representative because it is distinct from all others.

USEFUL FEATURES IN CLASSIFICATION

EMBRYONIC FEATURES– use in classification to differentiate higher taxa to assess the relationships among phyla which allow them to be placed in phylogenetic sequence since the strongest links between phyla and arrangement of phyla together into lines of decent depend on fundamental processes occurring in the egg/embryo.

Types of Eggs in Animals• Isolecithal/homolecithal– generally small eggs; yolk is equally

distributed throughout the egg.-undergo a complete cleavage formation during

development resulting to nearly equal-sized blastomeres.

• Telolecithal– yolk is concentrated near the vegetal pole of the egg.

-cleavage formation depends o the yolk’s amount in the vegetal pole:

It would be holoblastic if the yolk is not great but will produce two different-sized blastomeres (micromeres—ectoderm; and the macromeres—endoderm)

It would be meroblastic if the yolk is great and the cleavage is restricted to the superficial layer of protoplasm at the animal pole.

• Centrolecithal– yolk is concentrated in the center with musk of living protoplasm surrounding it at the outside. The cleavage here it meroblastic.

Pattern of Cleavage• Radial– cleavage planes producing the successive sets of

blastomeres are at right angle to each other and perpendicular/parallel to the polar axis of the fertilized egg; this forms an indeterminate cleavage.

• Spiral– cleavage planes tends to be oblique or diagonal to the polar axis of the egg and successive cleavage produces blastomeres arranged spirally around the polar axis that each successive tier of blastomeres rests above the grooves between the blastomeres’ tier below; produces determinate cleavage.

Body Cavity• Pseudocoelum– persistence into the adult stage of the

embryonic blastocoel cavity found in the gastrula stage; is not lined by mesoderm.

• Coelum– body cavity which is line by mesoderm (peritoneum in adult)

-enterocoelus– coelum arises as puches which bud off the archenteron of the gastrula and subsequently fuses.-schizocoelus– coelum arises as a split in the mesoderm which is forming in bands near blastomeres.

Along coelumate animals there’s strong tendency for spiral, determinate cleavage and schizocoelus coelum formation to be linked together while radial, indeterminate cleavage found in animal showing enterocoelus cleavage formation.

Through these fundamental differences in embryology, it is possible to divide coelumate animals into two fundamental lineage of evolution:

Deuterostome– radial, indeterminate, and enterooelus; mouth arises away from blastopore. Protostome– spiral, determinate and schizocoelus; mouth arises at or near the blastopore.

General chracteristics

Presence of body wall unperforated and digestive cavity– EUMETAZOA Body wall pierced by pores and absence of digestive cavity–PORIFERA (Parazoa)

Eumatozoa is divided into two great lines of Evolution:

• Protostomia-- usually have trocophore type if they have larva.• Deuterostomia– usually don’t have trocophore type if they have larva.

-- these two are distinguished according to embryonic characteristics and larval types.

Eumatozoa is divided according to germ layers laid down in the embryo:

• Diploblastic– e.g. Cnidaria and Ctenophora• Triploblastic– e.g. all other phyla of Eumatozoa

•BODY PLANS-Eucoelomata– having body cavity lined by peritoneum where excretory and reproductive ducts lead to the exterior.-Pseudocoelomata-- unlined by peritoneum.-Acoelomata– lacking body spaces.

Presence of Backbone of Vertebrae• Present vertebrae– vertebrates• Absent vertebrae– invertebrates

Other Characteristics

Symmetry Assymetrical (protozoans) Spherical (few protozoans) Radial (cnidarians and adult echinoderms) Bilateral (most phyla except the previously mentioned

phyla)

Segmentation-Chordates have mainly internal segmentation especially humans-Arthropods have mostly external metamerism-annelids has conspicous metemerism both externally and internally.

Appendages Skeleton

Sex Monoecious Dioecious

Larvae

NOMENCLATURE

Common name/vernacular name– the name for animals in a certain place in which it is commonly known.(e.g.

Scientific name– name applied to organism as taxonomic name

- Long descriptive polynomials in Latin (e.g. Turdus minor cinereo-albus maculatus which means Thrugh small grayish-white spotted)

- binomial nomenclature (Mimus polyglottis)- Trinomial (e.g. Passer domesticus domesticus and

Passes domesticus niloticus)

Rules of Scientific Nomenclature (by International Congress of Zoology– International Rules of Zoological Nomenclature), 1901 (Revised, 1961)

1. Zoologic and botanic names are distinct.2. No too genera in Animal Kingdom may bear the same name, the

same applies to two species in a genus.3. No names are recognized prior to those included by Linnaeus in the

System naturae, 10th edition (1758).4. Scientific name must be either Latin/Latinized and preferably

printed in italics.5. Genus names must be a single word (nominative singular) and

begin with a capital letter.6. Species names should be a single/compound word beginning with

small letter.7. The author of the scientific name is the person who first publishes it

in a generally accessible book or periodicals with a recognized description of the animal.

8. When a new genus is proposed, the type of species must be indicated.9. A family name is formed by adding –IDEA to the stem of the name of the type genus and a subfamily name by adding –INAE.

Thank you!

Jonalyn D. LelisBSED-2B