NEET SHORT NOTES & TRICKS:
❇️PHYLUM - ARTHROPODA❇️👉Arthropoda is the largest phylum of animalia which includes insects. Overtwo-thirds of named species on earth are arthropods
👉Body is Bilaterally symmetrical, Triploblastic with organ system level of organisation
👉They are metamerically segmented and coelomate animals.
👉Body is divided into three region Head, thorax & abdomen, but in some head and thorax fused to form cephalothorax(Prosoma)
👉They have jointed appendages for different functions. (arthro - jointed, poda- foot/appendages).
👉The body of Arthropods is covered by Chitinous exoskeleton
👉 Respiration by gills (e.g.Prawn), Book-gills (e.g.King crabs). Tracheal system (e.g Insects), Book-lungs(e.g.Scorpion), Trachea carry oxygen directly to the body cells
👉Circulatory system is Open type
👉Sensory organs like simple eyes, or compound eyes or both, antennae, statocyst and anal cerci are found.
👉They are mostly dioecious. Fertilization is usually internal but few aquatic form has external fertilization.
Gonads have ducts. Sexual dimorphism may be present. They are mostly oviparous.
👉Dovelopment may be direct or indiret.
👉Gregarious pest - Locusta (Locust)
• Living Fossil - Limulus (King crab)
❇️ PHYLUM - ANNELIDA ❇️
👉Free living found in moist soil (Terristrial), fresh water or marine but few are parasite.
👉Body is soft elongated, cylindrical and divided into segments or metameres by ring like grooves called Annuli.
👉They are bilaterally symmetrical, triploblastic and have organ system level of organisation with tube within tube body plan.
👉 They are metamerically segmented and coelomate animals.
👉 Circulatory system is closed type
👉.Excretory organ is Nephridia (sing. nephridium). They also help in osmoregulation
👉Nervous system consists of a nerve ring (Brain) and a solid, double and ventral nerve cord with ganglia.
👉Reproduction is sexual,Nereis is dioecious but earthworms and leeches are monoecious.
