Transcript Unit 2

Animal Classification
 Classification
system- Taxonomy
 Invertebrates Vs Vertebrates
 Phyla
 Agricultural Importance of Invertebrates and
Vertebrates
 Characteristics of Invertebrates.
 Incomplete and Complete Metamorphosis
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Since there is such a variety of living things, it is
important that we are able to put them into groups.
This is known as classification and the area of study is
called taxonomy.
The method used today classifies organisms into one of
five different Kingdoms, based upon similarities in their
structures.
The five Kingdoms are Monera, Fungi, Protista, Plantae
and Animalia.
Kingdoms are further classified in Phyla (Phylum in
singular), then into Classes, then Orders (sometimes),
then Families (sometimes) and then the organism is
given a Genus and Species Name.
 Animals
are classified into two main groups,
Invertebrates and Vertebrates.
 Invertebrates
(slugs and insects) do not have a
backbone, while vertebrates (Humans, birds and
mammals) do.
 The
animal kingdom is further divided into 20
phyla, of which the following are of agricultural
importance:
 This
Kingdom includes many unicellular freeliving animals called protozoans (one cell).
 It was previously considered a phylum to the
animal kingdom, but has recently been placed in
a Kingdom of their own along with Algae.
 Most of them live in water, either seawater, fresh
water or soil borne water.
 They are nearly all microscopic.
 The various species of Protozoans move in a
number of ways:
• Pseudopodia (False feet)
• Cilia (Small moving hairs)
• Tails
 Reproduction
of protozoans occurs by means of
binary fission or mitosis.
 Amoeba is one of the most common protozoans
and moves by means of pseudopodia.
 One of the most agriculturally important species
of Protozoans is Babesia.
 This protozoan causes Red-water Fever, a
disease that affects 100,000 cattle a year.
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The phylum Platyhelminthes are dorso-ventrally
flattened and have a definite anterior and posterior end
giving them bilateral symmetry.
Some flatworms are parasites, while others are freeliving carnivores or scavengers.
Examples of parasitic flatworms are flukes and
tapeworms.
Flatworms also have only a mouth for both food and
wastes.
Their nervous system is composed of a nerve net and
sometimes light-sensitive eyespots at the anterior end.
The phylum is classified into three main groups or classes:
• Class Turbellaria (Free living)
• Class Trematoda (Parasitic Flukes)
• Class Cestoda (Parasitic Tapeworms)
All platyhelminths are hermaphrodites (are both male and
female) and can, if required, can fertilise themselves.
 The
most important agricultural species of
platyhelminths is the Liver Fluke or Fasciola
hepatica.
 The life cycle of the liver fluke is very important
in finding ways of controlling the disease.
 The Life cycle is complicated and the fluke must
lay huge amounts of eggs to survive.
 The lifecycle takes place in the cow, on grass and
in a secondary host (the mud snail).
 The
Liver fluke lives in the ducts of the liver.
 The fluke lays eggs in the bile ducts (20,000 or
so a day)
 The eggs pass in the faeces and hatch two weeks
later in water and form a ciliated Miracidium.
 The Miracidium enters the foot of the mud snail
and changes into a Sporocyst.
 Still inside the snail, the Sporocyst changes into a
Redia.
 The Redia then produce very small tadpole
shaped Cercaria.
 For
every Miracidium that enters the snail,
10,000 Cercaria can be produced.
 The
Cercaria then leaves the snail and goes onto
grass.
 There
it becomes encysted (forms a shell) and
waits to be eaten by a sheep or cow.
 If
eaten, the stomach acids dissolve the cyst and
the liver fluke moves to the liver and restarts the
cycle.
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Understanding the lifecycle of the liver fluke
allows us control the spread in the following
ways:
Dosing any animals to kill the adult fluke
Spraying molluscicides to kill the snail.
Draining land (the snail only lives in water)
Fencing flooded areas
Don’t graze wet lands after August
 The
phylum Nematoda are the roundworms.
 Roundworms are cylindrical in shape,
tapered at both ends, and vary in length from
being microscopic to 20 inches long.
 Unlike flatworms, roundworms have a complete
gut.
 This means that they have a one-way digestive
tract with a gut that begins with a mouth and
ends with an anus.
 Therefore, they are usually able to digest
food.
 However, roundworms have no blood or
heart.
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Most roundworms are parasites and are found in all
habitats.
They have separate sexes generally and reproduce
sexually.
The roundworm Trichinella, causes the disease
called trichinosis.
People get trichinosis from eating infected,
undercooked pork.
All these worms reproduce by laying thousands of
eggs, which become encysted in the grass and wait to
be ingested.
The most important agricultural species are:
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Lungworms (Causes Hoose)
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Hairworms (Worms in school children)
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Potato eelworm
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Stomach worms
 Trichinella
gets into muscles and leaves
calcium deposits which effect muscle
contraction.
 Trichinosis can affect the heart.
 Another roundworm, Ascaris, parasitizes
human lungs.
 The Filaria worm attacks the lymphatic
system causing great swelling.
 This condition is called elephantiasis.
 Hookworms and pinworms are also
roundworms which parasitize humans.
 The
phylum Annelida are the segmented
worms and are abundant in all habitats.
 Segmentation gives worms more flexibility in
movement.
 If one segment is damaged, it isn't usually fatal to
the animal because their organs are duplicated in
other segments.
 Annelids have a A tube within-a-tube body
plan known as a coelom which is fully lined and
contains the body organs.
 The coelom runs from the mouth to the anus.
 Annelids have bilateral symmetry and a welldeveloped brain.
 Earthworms belong to this phylum.
Each segment of the earthworm has setae or external
bristles made of chitin. These bristles allow the
earthworm to move and to burrow into soil.
 Earthworms have a head and a central nervous
system.
 Earthworms respire through their moist skin as they
dig through the soil and help loosen it.
 They have a closed circulatory system in which
blood is pumped by five pairs of hearts.
 Most earthworms feed on decomposing vegetation
causing it to decompose faster.
 Earthworms bring the nutrients from the subsoil to the
top soil, thereby helping plants to grow.
 Undigested materials or castings are deposited
outside burrows.
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They eat their way through the soil and mix the
ingested material with mucus in their guts.
This helps to improve soil crumb structure.
Depositing soil in different places and mixing
horizons.
Improve drainage of heavy clay soils
Introduces more air into the soil.
When they die the further increase the amount
of organic matter.
 The
molluscs include slugs, snails, squid,
mussels, clams and octopus.
 These
animals generally have a foot, which
excretes a slimy mucus.
 They
 The
also have a rasping tongue.
most important mollusc is the mud snail
(Lymnaea truncatula)
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The members of the phylum Arthropoda all have
jointed appendages. In fact, the word "arthropod"
means jointed leg.
There are more species of arthropods than any other
phylum.
Arthropods have these characteristics:
• Hard exoskeleton which is usually composed of
substance called chitin
• Go through periodic ecdysis (moulting) as they
shed or moult their exoskeleton
• They have specialized body segments
(head, thorax, cephalothorax, & abdomen)
• Jointed appendages such as legs, antenna, and
mouthparts.
• Open circulatory system (blood is pumped out
of blood vessels into the body)
The most important groups of arthropods are as insects,
spiders and crustaceans.
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They have three main body parts: Head, thorax
and abdomen
They include aphids, lice, fleas, crane-flies and
butterflies.
The life cycle of all insects follows this path:
Egg
Larvae
Pupa
Adult
The larva is another name for a maggot and the
pupa is a cocoon.
The spider has two main body segments, the
cephalothorax and the abdomen.
 Some of the diseases spiders cause on the farm are
mange (scabies) and mite attack.
 Ticks are blood sucking spiders that can attack sheep
and spread disease (red water fever)
 Mange is again caused by borrowing into the skins
and laying eggs.
 The animal suffers from a severe allergic reaction
and secondary bacterial infection can occur.
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lot of the members of phylum Arthropoda are
Parasites.
 Parasites
are animals that live at the expense of
other animals.
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are two main classes of parasites:
 Endoparasite – inside animals
 Ectoparasites – outside animals.
 All
animals in the phylum Chordata have
backbones and are vertebrates.
 Examples include fish, birds, amphibians,
reptiles and mammals.
 The two main agricultural classes are Class Aves
(Birds) and Class Mammalia (Mammals).
 Only these two classes are said to be
homoeothermic – warm blooded – and can
regulate their body temperature.
 All
members of this class have feathers, no teeth
but a beak, lightened bones and no bladder
All mammals have the following traits:
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Hair
A Placenta
Mammary glands to produce milk
Again they are further classified into sub
classes.
Some of the common sub classes are:
Carnivores (Dogs and cats)
Ungulates (Hooved animals)
Odd toed - horse
Even toed – sheep, cattle
Marsupials – kangaroos
Primates – monkeys and humans