1 Basic concepts of animal structure

The adjectives of animal anatomy - essential vocabulary.
Points or parts of the animal body.
From molecules to meat - the range in size and complexity.
Farm animals versus other animals - farm animals in a zoological context.

1.1 Adjectives of position

 A number of anatomical terms are needed to describe the relative positions of structures within the body.  Study hint: it is absolutely essential to know and understand these terms.
anterior & posterior

1.2 Types of farm animals

Species is plural.  One species - two species.  The singular, specie, has no connection to farm animals or science at all.  Specie is small change - dimes and pennies.

Adjectives describing species. The names for different types of farm animals also may be unfamiliar to some readers. The adjectives that relate to cattle, sheep and pigs are bovine, ovine and porcine, respectively. The first of these may be used elliptically so that bovine may stand for bovine animal.

Male versus female. For cattle, sheep, pigs and poultry, the sire or father is called a bull, a ram, a boar or a cock (tom in turkeys), respectively, while the dam or mother is called a cow, a ewe, a sow or a hen, respectively.

Immature animals. A heifer is an immature female bovine, and a gilt is an immature female pig. A hogget is a yearling sheep.

Neonates. The neonates or new‑born of cattle, sheep and pigs are called calves, lambs or piglets, respectively. For pigs, the process of birth or parturition is called farrowing. Newly hatched chickens, turkeys, ducks and geese are called chicks, poults, ducklings or goslings, respectively.

Castrates. For cattle, sheep, pigs and poultry, a castrated male is called a steer, a wether, a barrow or a capon, respectively.

1.3 Points of a pig

Canadian students raised on a farm are not going to need this - but many of our students come from the big city or have English as a second language.

points of a pig

1.4 Points of a beef animal

beef points

1.5 Points of a lamb

lamb points

1.6 Range in size & complexity

The live animal is slaughtered  to produce a carcass composed of edible meat (muscle), fat (adipose tissue) and bone. The viscera (guts) are removed at slaughter. Muscle, fat and bone are tissues - this describes their composition rather than their position. Individual muscles and bones have names, whereas fat is described as subcutaneous (under the skin), visceral (around the guts), intermuscular (between muscles) and intramuscular (within muscles).

Study hint: do not confuse the two prefixes 'intra-' and 'extra-'.  Intra- means within.  Inter- means between.

Tissues have distinct functions. Muscle tissue contracts to create movement. Adipose tissue stores energy and provides thermal and mechanical insulation. Bone provides support.

All tissues are composed of cells, and many are held together by fibres.  Cells and fibres are often surrounded by a back-ground material or matrix. Tissues are spread throughout the body and occur at many different locations.

Organs are distinct anatomical structures with one or more functions. The heart pumps blood through the vascular system.  The lungs add oxygen and remove carbon dioxide from the blood. Organs usually contain several types of tissue - the heart, for example, is dominated by cardiac muscle tissue but also contains vascular tissue (its own blood supply), nervous tissue (to control heart rate), and connective tissue (forming valves, holding the heart together and isolating the heart in the thoracic cavity).

Tissues and organs are mostly visible by eye - without a microscope.  Individual cells can only be seen with a microscope.

Inside cells are organelles - specific parts of the cell with special functions.  For example, inside muscle fibres (the fibre is a giant cell with many nuclei), are organelles called myofibrils responsible for contraction. The cell nucleus contains genetic information coded in DNA (deoxyribonucleic acid).

Myofibrils are very important in this course - because meat is very important in animal agriculture.  Meat is either the primary product (beef, pork, lamb and poultry meat) or the terminal product (dairy cows, wool sheep and spent laying hens) of animal agriculture. Myofibrils are composed of very large proteins just individually visible at the highest magnifications of electron microscopy.

1.7  Animal classification

The principles of animal classification are fairly simple - but the details are very complex. The animal kingdom is divided into a number of phyla (singular, phylum).  The word is taken from the Greek word, phylon, meaning a race or tribe.  Here are some major phyla.
Each phylum is divided into classes, and classes are further subdivided into orders. Phylum Chordata contains the two classes which interest us here.

There is something important in the way animals developed two openings to the gut (mouth + anus). If the original single opening became the mouth, they are called protostomes (first mouth). But if the original single opening became the anus, so the mouth was developed from a second, new opening they are called deuterostomes (second mouth). All the phyla with both mouth and anus above the line (******) in the list are protostomes, while the two phyla below the line are both deuterostomes. It may be difficult to grasp we and our farm animals evolved from radially symmetrical animals, but their remote ancestors  looked a little like ancient fossil fish with a heavy armoured skull propelled by a flexible tail. I believe it. You can believe what you want.

Further information

R.C. Brusca & G.J. Brusca. (1990).  Invertebrates. Sinauer Associates, Sunderland, Massachusetts. This is the best invertebrate zoology text I have ever used.  Big and heavy - something to browse for real details. There is a later edition.

H. Gee. (1996).  Before the Backbone.  Chapman & Hall, London.  This is a brilliant exposition of a very complex field.  It explains likely routes for the origin of chordates from invertebrates.  Easy to read the whole book.


Zoological illustrations - water colours of common live animals plus a museum rarity.
Ciliophora.  This Vorticella , a ciliophoran with a stalk, was under my deck on the Mad River at Singhampton, Ontario.
Porifera.  Spheciospongia vesparium, the common loggerhead sponge was at Cayo Coco, Cuba.
Cnidaria. Gorgonia flabellum, venus sea fan. Playa Esmeralda, Cuba.
Platyhelminthes. Planaria, in 3 moving poses. Grand Mannan Island, New Brunswick.
Annelida. Nephtys, red-lined worm. Playa Esmeralda, Cuba.
Arthropoda.  Eriphia sebana,  red-eyed crab,  on the Great Barrier Reef, off Heron Island, Australia.
Mollusca. Octopus briareus  in a rockpool on the Island of Fernando de Noronha off the coast of Brazil.
Echinodermata. Bohadschia graeffei, sea cucumber, on the reef off Rarotonga in the Cook Islands.
Chordata. Arapaima gigas, Sakurajima Museum Japan.
Aves. Just one puffin in three poses, Fratercula artica,  on Skomer Island, UK.
Mammalia. Aepyceros melampus,  Kruger Park, South Africa.