BIOMI 3310 Lecture Notes - Lecture 12: Gongylonema, Subcutaneous Tissue, Histomonas Meleagridis
Document Summary
Ecdysozoa have 4 molts and 5 stages (larval stages 1-4 and adult stage): Nematode: roundworm: belongs to ecdysozoa, no segmentation, pseudocoelomate (tubes floating within tubes, complete gut. Important distinction: platyhelminths are acoelomate: marine, free-living, plant and animal parasitic, 33% of nematodes described occur as vertebrate parasites, high internal pressure. Soft bodied - don"t leave much of a fossil record. Evidence of the first nematodes: 500-400 mya (cambrian period) First parasitized plants: ~400 mya: evidence: mineral deposits in the rhynie chert (early devonian) First parasitized invertebrates: ~144 mya (early cretaceous: evidence: adult midge preserved in amber had a nematode in its body cavity. First parasitized animals (i. e. vertebrates): ~240 mya (triassic: evidence: found in cynodont coprolites (mammal-like reptiles, nematodes are practically non-existent as parasites of invertebrate and vertebrate marine taxa (mollusks, polychaetes, crustacea, sharks, etc. ) Feed with ochiostyle (tooth-like spear in buccal cavity: class secernentea, tylenchida. Some are parasites of invertebrates (insects, mites, leeches: rhabditida.