Mada za sehemu hiiNatural Groups Of OrganismMada 26
- General overview of classification
- Viruses.
- Kingdom Monera
- Kingdom Protoctista
- Phylum Rhizopoda
- Phylum Zoomastigna
- Phylum Apicomplexa
- Phylum Euglenophyta.
- Phylum Oomycota.
- Phylum Chlorophyta.
- Kingdom Fungi
- Phylum Zygomycota
- Phylum Ascomycota.
- Phylum Basidiomycota
- Advantages and disadvantages of the kingdom Fungi
- Kingdom Plantae
- Division Bryophyta.
- Division Filicinophyta (Pteridophyta).
- Division Coniferophyta (Conifers).
- Division Angiospermophyta (flowering plants)
- Kingdom Animalia
- Phylum Platyhelminthes
- Phylum Aschelminthes (Nematoda)
- Phylum Annelida.
- Phylum Arthropoda.
- Phylum Chordata
Nematodes or round worms are the most numerous multicellular animals on earth, and inhabit a wide range of environments.
Many of them are parasites of animals (including humans) and plants. They may cause serious diseases that are deleterious to human health and agricultural productivity.
The free-living species inhabit marine and freshwater environments, as well as the soils and sediments of all of the various types of terrestrial biomes. Examples of Nematodes include: Ascaris lumbricoides (the pig and human nematodes), Wuchereria bancrofti (infecting human lymphatic system), hook worms (blood-feeding parasite of human and other animals) and Meloidogyne incognita (plant root knot nematode).
Ascaris are round, slender unsegmented worms with tapering bodies at both ends. They are characterised by being tubes within tubes, referring to the alimentary canal, which extends from the mouth on the anterior end to the anus, located near the tail. They possess digestive, nervous, excretory and reproductive systems, but they lack distinct circulatory and respiratory systems. The male and female Ascaris differ in morphology, as male is smaller and more curved at its posterior end than the female. They lack locomotory organs; movement is by undulating bodies in dorso-ventral waves.
- It produces chemicals, which act as anti-enzymes to the digestive enzymes of the host.
- It has an alimentary canal, which opens at the mouth and anus. This enables the parasite to take food from the hosts' digestive system.
- It possesses digestive enzymes in its digestive system for the completion of partially digested food from the hosts' alimentary canal.
- It has sensory papillae around its mouth for detecting food present in the elementary canal of the host.
- It respires anaerobically, and have low metabolic rate; hence, they are able to live inside the host's intestine.
- It has high reproductive potential; thus, by producing large number of eggs, it ensures its survival and existence.
- The pharynx has valves, which prevent regurgitation of the ingested food.
- Nematodes, such as Ascaris are used in biological studies in different ways; for instance, in laboratory practical studies.
- Some nematodes are used as biological control agents for pest insects. They attack insects and kill or hinder their development.
Some Aschelminthes are parasites and cause diseases in plants and animals. Examples include:
- Wuchereria bancrofti that causes elephantiasis. This disease infects the human lymphatic system by blocking it; resulting in the accumulation of the lymph in legs, hands, and/or scrotal sacs.
- Ascaris lumbricoides causes ascariasis in humans that may lead to obstruction in the gut and anaemia.
- Meloidogyne incognita causes root knot galls in plants that drain photosynthetic products; hence, affect plant growth and reduce yield.
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