Onychophora

• Phylum Onychophora

  The "velvet worms"
• Onychophora traits

  • Claws on end of appendages (lobopods) (have appendages like arthropods but it not jointed)
  • Thin, non waxy cuticle (similar to arthropods)
  • Require moisture
  • Nocturnal
  • Found in moist, warm environment (tropics)
• Onychophora feeding

  • Attack prey by shooting glue from oral papillae with large slime glands
  • Similar to the way spiders excrete web
• Onychophoran synapomorphies

  • 2nd pair of appendages modified to form jaws
  • 3rd pair of appendages form oral papillae
  • Slime glands discharge glue throat opening on oral papillae
  • Subcutaneous hemal channels beneath the cuticle form part of the hydrostatic skeleton
• Onychophora morphology

  • Unjointed lobopod legs, with claw on end
  • Legs filled with haemocoelic fluid
  • Hydrostatic skeleton
  • They have a water skeleton, no hard skeleton
  • Hemal channels
  • They can be filled with a fluid, retract or attract
  • They have no joint, they can flex in different directions
  • Don't have good vision
  • Active in night
  • Rely on feeling, touch
  • They have a brain
  • They have circular muscle
• Onychophora reproductive strategies

  • Gonochoristic
  • Oviparous (have eggs)
  • Viviparous (live birth)
  • Ovoviviparous
  • Viviparous females have placenta
  • Oviparous eggs are large and yolky
• Features shared with arthropods

  • Growth by molting
  • Reduced coelom
  • Heart with ostia
  • Striated muscle present in jaws
  • Trachea-spiracle system
  • Large, well developed brains
  • Antennae