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BIOLOGY FORM 4

BIOLOGY FORM 4. INVERTEBRATES ARTHROPODS. ARTHROPODS. Phylum TARDIGRADA Phylum PENTASTOMA Phylum ONYCHOPORA. What is Arthropods. Protostome Very diverse BUT share TWO characteristics anatomical features:

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BIOLOGY FORM 4

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  1. BIOLOGYFORM 4 INVERTEBRATES ARTHROPODS

  2. ARTHROPODS • Phylum TARDIGRADA • Phylum PENTASTOMA • Phylum ONYCHOPORA

  3. What is Arthropods • Protostome • Very diverse BUT share TWO characteristics anatomical features: • Pair of legs along all OR part of the body (served by ganglionic swellings on the latitudinal nerve cords • Pseudocoelomic body cavities (filled with blood – haemocoels)

  4. Cont. • Arthropod body plan: • Small anterior region (acron) • Equivalent posterior portion (telson) without legs • Number of intervening section (segments) with a pair of legs each • BUT non-leg-associated (respiratory, excretory) organs are not serially repeated

  5. Phylum TARDIGRADAe.g: water bears

  6. Water bears??

  7. What is Phylum TARDIGRADA? 400 living species in 1 class • Characteristics[size: 0.05 – 1.2 mm] • Bilaterally symmetrical, minute, squat • Body more than 2 cell layer thick • Straight gut • Body monomeric – • four pair of short unjointed claw-bearing legs • Crawl by extrinsic muscle • Legs served by nerve ganglia • Well develop pseudocoelomic cavity => hydrostatic skeleton • Body wall with cuticle-covered epidermis without muscle • Non-chitinous cutilce moulted, bear spines or thickened into plates • Network of smooth muscle criss-cross the body

  8. Cross Section of water bears

  9. Phylum PENTASTOMA

  10. Cont. 100 species placed in 1 class • Characteristics[size: 2 – 16 cm long] • Bilaterally symmetrical, flattened, vermiform • Body more than 2 cell layer thick • Straight gut • Body monomeric – • annular • 2 pair claw-bearing legs at anterior • OR two pair of claw • Pseudocoelomic hydrostatic skeleton • Body wall with cuticle-covered epidermis • Layer of striated circular and longitudinal muscle • Cuticle chitinous, porous and moulted

  11. Cross Section of Pentastoma

  12. Phylum ONYCHOPORA

  13. Cont.

  14. Phylum ONYCHOPORA 70 species placed in 1 Class, 1 Order • Characteristics[size: up to 15 cm long] • Bilaterally symmetrical, elongately and cylindrically vermiform • Body more than 2 cell layer thick • Straight gut bearing pair of mouthpart with 2 claw-like mandible • Fore- and hind-guts line with cuticle without digestive diverticula • Body 14-43 pairs of short unjointed fleshy legs along • Each leg: hollow evagination of body, padded terminally, with pairing claws and intrinsic muscle • Legs associated with a pair of heart ostia and excretory organ • Well developed haemocoelomic body hydrostatic skeleton with tubular heart but no other blood vessel

  15. Cross Section of ONYCHOPORA

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