LECTURE 1: INTRODUCTION TO THE UNIT AND TO THE STUDY OF ANIMALS
Biologists have identified >1.3 million living species of animals.
Binomial nomenclature: two part scientific name in italics. Genus, species.
Animals are grouped into 8 hierarchical groups which was first devised by Linnaeus.
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species. DKPCOFGS
Taxon: named taxonomic unit at any hierarchy
Classification can also be used to illustrate evolutionary history or phylogeny. Animals may be reclassified or
inserted into different categories (sub or super categories)
PhyloCode/ Cladistics: based entirely on evolutionary relationships. Aims to create a tree that depicts the
evolutionary events and hence evolutionary relationships.
Monophyletic groups: contains recent common ancestor and all of its descendants. Branch points represent
divergence from a common ancestor (monophyletic group). A branch point can also form a polytomy (an
unresolved pattern of divergence.)
Sister taxa: two decendants that split from the same node are called sister taxa. They are each others closest relatives.
Polytomy: an international node of a cladogram that has more than 2 immediate descendents (sister taxa)
WHAT IS AN ANIMAL
Nutrition: obtains nutrients by eating other organisms.
Eukaryotic, multicellular (large size and greater complexity), lack cell walls composed of cellulose, have cells held together by protein (collagen) and
usually contain 2 specialised cell types (nerve and muscle cells.)
Animals reproduce sexually.
Somatic cells: diploid (2 sets of chromosomes)
Gametes (sperm and eggs): cells undergo meiosis to form haploid sex cells (1 set of chromosomes). Haploid sex cells fuse to form diploid organism.
Allows mixing of genes. More phenotypes upon which natural selection can work on.
• According to different body plan (eg. Single cells or multicellular, cephalisation-definite head, cell walls, symmetry and organelles).
• Higher taxa (kingdom, phyla) gross differences shared by all: multi-cellularity, symmetry and tube within a tube.
• Lower taxa (class, order): specific differences shared by some.
• Radial symmetry: cut in half along any plane to give a mirror image. All sides have an equal chance of catching prey (sessile animals).
• Bilateral symmetry: cut along one plane to give a mirror image.
• Cross section: diploblastic (2 cellular layers, ectoderm and endoderm) or triploblastic (3 cellular layers, ectoderm-skin, mesoderm-muscles,
endoderm-lining of digestive tract)
LECTURE 2: CELLS, TISSUES AND ORGANS
The biological hierarchy of organisation: cells, tissues, organs, organ systems, whole organism.
The physiology of the whole organism depends on the coordinated function of its organ systems.
Tissues: cells with similar functions grouped together. The 4 main tissue types are epithelial, connective, nervous and muscle tissue.
Covers the body, lines organs and cavities. Cells are bound together by a tight junction.
Apical surface = towards Basal lamina= separates epithelial from underlying tissue
Types of epithelium:
• Simple cuboidal: diced shaped cell specialized for secretion.
• Stratified cuboidal
• Simple columnar: lines the intestines secreting digestive enzymes and absorbing nutrients.
• Stratified columnar
• Simple squamous: thin cells that aid in diffusion.
• Stratified squamous: regenerates rapidly helping surfaces that are subject to damage.
• Basement membrane (basolateral surface): mat of collagen fibres
• Pseudostratified: composed of a single layer of cells, although has nuclei position to
suggest stratified epithelium.
Binds and supports other tissues. Composed of cells (secrete the matrix) and matrix (liquid, jellylike
Collagenous fibres: collagen, tough and non-elastic.
Elastic fibres: elastin and elastic.
Reticular fibres: collagen, fibrous mat that joins connective tissue to adjacent tissues
find more resources at oneclass.com
find more resources at oneclass.com