Week 8.2 Ecdysozoa - Slides & Notes PDF

BIO1427 – Ecdysozoa: Nematodes & Pan-arthropods Recorded 8.2 Jolyon Troscianko  Understand: Key features of the basal Ecdysozoa: Nematoda, Tardigrada & Ony...

BIO1427 – Ecdysozoa: Nematodes & Pan-arthropods Recorded 8.2 Jolyon Troscianko  Understand: Key features of the basal Ecdysozoa: Nematoda, Tardigrada & Onychophora Learning Objectives The niche and ecological importance of Nematodes The life-cycle of some key nematode parasites and some fundamentals of their interaction with hosts Basics of the pan-arthropods Just a warning – there are plenty of disgusting pictures of parasitic worms and their hosts Not nature at its most beautiful!  Porifera ANCESTRAL Metazoa COLONIAL Ctenophora FLAGELLATE Eumetazoa Ecdysozoan Phylogeny Cnidaria Acoela Echinodermata Cambrian group split Deuterostomia from other Bilateria Chordata Platyhelminthes Protostomes 18,500 species (but half of these are parasitic, and true number is likely far higher, maybe nearer 1 million) Nematoda  Micrographs of Nematode basics: marine nematodes Extremely abundant Widely distributed; present in every habitat where there is sufficient moisture (marine floor, soil, aquatic, terrestrial, hot springs, polar ice, inside plants and animal tissues) Nematoda Specialists of interstitial spaces (squished spaces between layers, from soil to host cells), water film covering soil Non-parasitic species typically feed on bacteria or fungi ↳ Ecologically critical for nutrient cycling Many species of health & economic importance plant parasites: dog lungworm root knot nematodes Angiostrongylus Abundance: 1 sqm of ocean sediment can contain 4 million individuals from hundreds of species 10-100 per gram in middle latitudes- 100-1000 million per acre of soil 90,000 individuals found in one apple Parasitic nematodes are major pests of plants, including all grains, fruit, veg and pasture Nematoda Fungi trapping & consuming nematodes While many nematodes consume fungi, there are also many types of fungi that prey on nematodes They typically attract nematodes by secrating chemical cues associated with nematode food The nematodes are then trapped in nets or nooses and the fungi then consume the nematodes  Nematode body plan basics: Cylindrical bodies typically