Question

What are characteristic features of phylum nematoda? Discuss its classification with examples. Answer?

Answer 1

$\huge\mathfrak{Answer:}$

Phylum Nematoda are un-segmented vermiform animals with ante­rior lateral chemosensory organs or amphids and with a persistent blastocoel or pseudocoelom; dorsal and ventral nerve cords in epidermis and excretory system of renette cells or tubules.

$CHARACTERISTICS:$

1. Body of Phylum Nematoda is un-segmented, bilaterally sym­metrical, elongated and tapering at both ends.

2. Triploblastic animals with perivisceral cavity is more extensive than that of Platyhelminthes.

3. Body of of Phylum Nematoda is generally covered with thick, flexible multi-layered collagenous cuti­cle and often bears cuticular setae (hairs), spines or annulations.

4. Cuticle moulted periodically.

5. Epidermis or hypodermis syncytial; i.e., the nuclei are not separated from each other by cell membranes.

6. Only longitudinal body-wall muscles; no circular body-wall muscles.

7. Body cavity of of Phylum Nematoda is pseudocoel filled with parenchyma in most cases.

8. Alimentary canal provided with distinct mouth and anus (complete digestive tract). Muscular pharynx and the inner surface of the gut usually not lined by cilia. Extracellular digestion.

9. Mouth of of Phylum Nematoda is surrounded by six lips.

10. Blood vascular system and respiratory system are absent in of Phylum Nematoda.

11. Haemoglobin sometimes present in the pseudocoelomic fluid.

12. Excretory system without nephridia and flame cells. In the class Adenophorea glandular renette cells with a duct or in the class Secernentea excretory canal system without flame cells act as excre­tory system.

13. Dorsal and ventral nerve cords in the epidermis.

14. Chemosensory organs are small cuticular projections called amphids which are situated on the lips, derived from cilia and opening to the exterior through a small pore, and lined with modified non-motile cilia called sensillae.


15. Sexes of of Phylum Nematoda are separate (gonochoristic).

16. Tubular gonads are present in of Phylum Nematoda.

17. Amoeboid sperm cells.

18. Fertilization is internal in of Phylum Nematoda.

19. Determinate cleavage (mosaic).

20. of Phylum Nematodaare eutelic animals.

21. Generally complex life history.

22. They are free-living or phytoparasitic or zooparasitic.

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Answer 2

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➧ Some Phylum in Animal Kingdoms are:-
▬▬▬▬▬▬▬▬▬▬▬▬▬⤵

❶❭ Porifera:-━━━━━━━━━━━━━━━☟

❱ Body is cylindrical & asymmetrical.

❱ Canal system is present.

❱ Cellular level of organisation.

❱ It is diploblastic.

❱ They reproduce by budding in Asexual Reproduction.

❱ Special cells are choanocytes.

❱ Skeleton is in the form of spicules.

▶Ex:- Sycon & Sponges

❷❭ Coelenterata:-━━━━━━━━━━━━━━━☟

❱ Body is Radially symmetrical.

❱ Canal system is absent.

❱ Tissue grade level of organisation.

❱ Body wall is diploblastic.

❱ Opening served by mouth & anus.

❱ Special Cell or Cnidoblasts.

❱ It occurs in the form of polyp & Medusa.

❱ It have gastrovascular cavity.

❱ It poses tentacles called Nematoblasts.

▶Ex:-  Hydra & Jellyfish

❸❭ Platyhelminthes:-━━━━━━━━━━━━━━━☟

❱ Body is bilaterally symmetrical, flattened & Ribbon shaped.

❱ Digestive system is absent or incomplete.

❱ Body cavity is absent.

❱ Body is triploblastic.

❱ It is bisexual or Hermaphrodite.

❱ Respiration is an aerobic.

❱ They possess sućker.

❱ Circulatory or respiratory system is absent.

▶Ex:-  Planaria & Tape worm

❹❭ Nematoda:-━━━━━━━━━━━━━━━☟

❱ Body is bilaterally symmetrical or cylindrical.

❱ Body has tissue level of organisation.

❱ It is mostly parasites organism.

❱ Body is triploblastic.

❱ Respiratory or circulatory system is absent.

❱ Sex are separate.

❱ They have tissue but no real organ.

▶Ex:-  Ascaris & Hook worm

❺❭ Annelida:-━━━━━━━━━━━━━━━☟

❱ Body is cylindrical, bilaterally symmetrical & metamerically.

❱ Body structure ring-like segment.

❱ Respiration by gills or moist skin.

❱ Body is triploblastic.

❱ Excretory organs are nephridia.

❱ Digestive & circulatory system are well developed.

❱ Locomotory organs are parapodia.

❱ They have true body cavity.

▶Ex:-  Earthworm & Leech

❻❭ Arthropoda:-━━━━━━━━━━━━━━━☟

❱ Body is bilaterally symmetrical & segmented.

❱ Exoskeleton shed periodically during growth.

❱ Body is covered with non living exoskeleton.

❱ Body wall is triploblastic.

❱ Body divided into head, Thorax & abdomen.

❱ It have jointed appendages.

❱ It possess compound eyes & antennae.

❱ Respiration by gills, trachea & book lungs.

▶Ex:-  Cockroach & Spider

❼❭ Mollusca:-━━━━━━━━━━━━━━━☟

❱ Body is bilaterally symmetrical.

❱ Shell formed of calcium carbonate.

❱ Body covered with mantal & hard shell.

❱ Body is triploblastic & Coelomate.

❱ Body divided into head, foot & visceral mass.

❱ Foot is ventral & muscular.

❱ Respiration by gills or ctenida.

❱ Blood may be Black - blue.

▶Ex:-  Octopus & Unio

❽❭ Echinodermata:-━━━━━━━━━━━━━━━☟

❱ Body is radially symmetrical.

❱ Body size is spherical or cylindrical.

❱ Body surface covered with spines.

❱ Body is triploblastic & have coelomic cavity.

❱ It possess power of regeneration.

❱ No head tail right & left side.

❱ Body differentiated into oral & aboral surface.

❱ It have water vascular system.

▶Ex:-  Starfish & Antedon

❾❭ Chordata:-━━━━━━━━━━━━━━━☟

❱ Nerve cord hollow tubular & dorsal.

❱ Notochord is present.

❱ Heart is ventral.

❱ Circulatory system is always closed.

❱ RBCs are present.

❱ Endoskeleton is present.

❱ A series of pharyngeal gill-silts present in the pharyngeal wall.

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