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Learn about the classification system and taxonomy of animals, including invertebrates and vertebrates, the different phyla, and the agricultural importance of these organisms.
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Leaving Certificate Agricultural Science Animal Classification
Learning Outcomes • Classification system- Taxonomy • Invertebrates Vs Vertebrates • Phyla • Agricultural Importance of Invertebrates and Vertebrates • Characteristics of Invertebrates. • Incomplete and Complete Metamorphosis
Introduction • 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.
Animal Classification • 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:
Kingdom Protista • This Kingdom includes many unicellular free-living 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
Kingdom Protista - 2 • 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.
Phylum Platyhelminthes • 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 free-livingcarnivores 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.
Phylum Platyhelminthes - 2 • 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).
Platyhelminthes - 3 • 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.
Platyhelminthes - 4 • 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.
Control of Liverfluke • 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
Phylum Nematoda • 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.
Nematoda - 2 • 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: • Lungworms (Causes Hoose) • Hairworms (Worms in school children) • Potato eelworm • Stomach worms
Nematoda - 3 • 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.
Phylum Annelida • 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 well-developed brain. • Earthworms belong to this phylum.
Annelida – The Earthworm • 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.
Earthworms and Soil • 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.
Phylum Mollusca • The molluscs include slugs, snails, squid, mussels, clams and octopus. • These animals generally have a foot, which excretes a slimy mucus. • They also have a rasping tongue. • The most important mollusc is the mud snail (Lymnaea truncatula)
Arthropoda • 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.
Arthropoda – Class Insecta • 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.
Class Arachnida • 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.
Phylum Arthropoda - Parasites • A lot of the members of phylum Arthropoda are Parasites. • Parasites are animals that live at the expense of other animals. • There are two main classes of parasites: • Endoparasite – inside animals • Ectoparasites – outside animals.
Phylum Chordata • 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.
Class Aves • All members of this class have feathers, no teeth but a beak, lightened bones and no bladder
Class Mammalia • All mammals have the following traits: • 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
