Kingdom Animalia

1. Kingdom Animalia Last day… introduction to animals & their characteristics

2. …covered early branches the Porifera (prob. monophyletic), Ctenophora & Cnidaria, the Acoela, and started the Lophotrochozoa

3. Began looking at phylum Platyhelminthes – the Flatworms - ~20,000 spp.? - also acoeolomate & triploblastic, but usually more complex than Acoela

4. covered Class Turbellaria… - mostly free-living, marine, a few freshwater - glide or swim - reproduce by fission, or sexual reproduction by hermaphrodites

5. Class Monogenea – monogeneans - external parasites of fish (or hippo) with relatively simple life cycles

6. Class Trematoda – Trematodes, or flukes - mostly internal parasites of a wide range of animals - have oral sucker near mouth & ventral sucker to attach - complex multinucleate covering helps fool immune system, resist digestive enzymes Fasciolopsis intestinal fluke

7. Have complex life cycles with intermediate hosts (often a mollusc) & different types of larvae - most hermaphroditic, but Schistosoma has males & females - schistosomiasis caused by blood fluke in intestinal or bladder veins, affects 200 million people

8. Class Cestoda – tapeworms - specialized parasites, mostly of vertebrates (including us) - scolex (‘head’) w. suckers & sometimes hooks to attach in intestines - no mouth or digestive system, just absorb nutrients - long ‘body’ of proglottids, mostly contain sex organs, detach & pass out in feces

9. Phylum Rotifera – rotifers – 1,800 spp. - tiny (0.5 – 2 mm) animals of aquatic or moist habitats, but w. complex bodies w. organ systems, e.g. alimentary canal w. mouth & anus, ‘jaws’ for grinding - has pseudocoelom - one class reproduces via unfertilized eggs producing only females, apparently for > 35 million years?

10. The lophophorates: 3 phyla actually have lophophores: crown of ciliated tentacles, draws water & food in - these phyla sessile, lack definite head, have U-shaped alimentary tract & true coelom

11. We look at 2 of those 3 phyla… Phylum Ectoprocta – the bryozoans (‘moss animals’) - 4,500 spp. - normally colonial, individual zooids not fully independent - filter-feeders, retractable lophophore - most marine, may be reef-builders (hard exoskeleton), but some freshwater spp. (9 in IL) Pectinatella magnifica

12. Phylum Brachiopoda – Brachiopods or ‘lamp shells’ - resemble tiny clams, but on stalk & w. lophophore inside - 2 halves of shell are dorsal & ventral (not lateral) - only in marine waters - scarce today (~335 spp.), but abundant in Palaeozoic

13. Move into group of phyla with trochophore larvae – first: Phylum Mollusca – the Molluscs (clams, snails, squids, etc.) - huge phylum (93,000 spp.?) of varied form, but same basic body plan: shell-secreting mantle covers visceral mass (w. major organs), foot for locomotion, digging) - mantle cavity houses gills, anus, etc.

14. Eight? living classes, but 4 most diverse are: Class Polyplacophora – Chitons - oval body, dorsal shell w. 8 plates (but body unsegmented) - foot for locomotion, and used as suction cup - like many molluscs, have rasping radula - use it to scrape algae off rocks

15. Class Gastropoda – snails and slugs - marine (most), fresh-water or terrestrial, by far the largest class (about 70,000 species) - head present, eyes on tentacles - terrestrial snails lack gills, respire through lining of mantle cavity

16. - embryo undergoes torsion during development: body twists up to 180°, bringing anus & mantle cavity over head - distinct from coiling of shell

17. Most gastropods herbivorous, but some predatory - radula modified to scrape flesh, bore holes in shells or as ‘harpoon’ - cone shells harpoon fish with fast-acting venom - complex venom used as pain-killer, & may have other uses

18. Class Bivalvia – clams, oysters, mussels, scallops… - shell with 2 halves, hinged mid-dorsally (so a left valve & a right valve)

19. Bivalves have no distinct head, & no radula - mantle cavity has gills for gas exchange & feeding - suspension feeders, and mostly sedentary - some burrow or move slowly w. foot, & scallops use ‘jet propulsion’ by rapidly opening/closing shell

20. - some bivalves have eyes & sensory tentacles at edge of mantle - giant clams may weigh > 220 kg, colorful due to algal symbionts

21. Class Cephalapoda – squids, octopuses, nautiluses - active predators with tentacles to grab prey, beak to bite & toxic saliva - well developed eyes, and regarded as very intelligent for invertebrates - jet propulsion from siphon

22. Chambered nautiluses have shell, but shell reduced & internal in squids, often absent in octopuses

23. Some squids quite large (Humboldt Squid – to 1m for mantle) - but giant squid (rarely seen alive) to 2.25 m for mantle, perhaps 13 m to ends of tentacles

24. …and Colossal Squid is largest invertebrate - only +/- complete specimens immature?, but adults estimated to reach 14 m - more robust body, relatively shorter tentacles, so weight at least 495 kg

25. Last of the lophotrochozoans… Phylum Annelida – segmented worms (‘little rings’) - 16,500 spp. in marine, freshwater & damp soil habitats - divided into 2 classes?

26. Class Oligochaeta – Earthworms - bristles or chaetae along side are sparse (4 pairs/segment) - tunnel through soil, consuming dirt & organic material, eliminating waste as ‘castings’ - ganglia above & below pharynx connect to ventral nerve cord - hermaphrodites, clitellum produces ‘cocoon’ for shed eggs & sperm - some may regenerate after fragmentation

27. Leeches - formerly separate class, now seem to be part of Oligochaeta - mostly fresh-water, a few terrestrial or marine - famous for blood-sucking but many are predators - have 2 suckers for attachment, but no chaetae or parapodia - blood suckers use anesthetic secretion, then anti-coagulant - still used medicinally to drain blood & anti-clotting drug

28. Class Polychaeta – the Polychaetes (‘bristle worms’) - each segment has pair of parapodia w. many chaetae - locomotion, & often function as gills - mostly marine, bottom crawlers or tube dwellers, some drift or swim

29. Some annelids famously big… - Giant Gippsland Earthworm – to 3 or 4 m long? - a South African sp. may be larger (report of 6.7 m) - giant reef bristle worms average 1m, but up to near 3 m, or more?? - and they have jaws!!

31. Have worked our way through Lophotrochozoa, sister group is the Ecdysozoa - perhaps the most successful animals of all?

32. Ecdysozoa identified as a monophyletic group by genetic data, but do share trait of ecdysis: shedding old covering & secreting new one to increase in size - includes 9 phyla, but 2 much more diverse than others…

33. Phylum Nematoda – Nematodes, or roundworms - unsegmented round bodies, usually small (but up to 1 m) - covered by tough cuticle - ubiquitous, in aquatic habitats, soil, & in other organisms - 25,000 spp. described, but might be 500,000, or 1,000,000 - pseudocoelomate, & no circulatory system - usually separate sexes & internal fertilization, zygote can withstand harsh conditions

34. - most nematodes free-living, feed on wide range of live & dead food, important in nutrient cycling - but many spp. are crop pests (often attacking roots) or parasites of many species, including humans - e.g. Trichinella spiralis from raw pork causes trichinosis

35. And now the big time! Phylum Arthropoda – Arthropods - by far the biggest phylum, ~2/3 of all described spp. are arthropods (~1,000,000 spp.)

36. In number of individuals & broad distribution, most successful of all animal phyla - likely related to body plan of phylum - plan includes segmented body (but specialized in regions) - hard exoskeleton protects, supports & prevents dessication - jointed appendages for mobility

37. - exoskeleton composed of a cuticle covering entire surface, composed of chitin (a polysaccharide) & protein - provides attachment points for muscles

38. Arthropods have well-developed sensory organs: eyes, simple or compound, olfactory/taste receptors, antennae for touch & smell - well cephalized - have various organs for gas exchange, e.g. spiracles leading to branched tracheal system in insects

39. Aquatic arthropods usually have gills with extensive surface area for gas exchange

40. Arthropods have open circulatory systems: hemolymph pumped by heart through arteries, but empties into sinuses, the hemocoel - not a coelom (true coelom is small in arthropods) - hemolymph flows around organs, then returns to heart via valved pores

41. 4 subphyla in Arthropoda, starting w. Cheliceriformes - named for chelicerae: claw-like feeding appendages, used as pincers or fangs - most of ~100,000 spp. are arachnids – spiders, ticks, mites, scorpions, harvestmen & sun spiders - cheliceriforms also include horseshoe crabs & perhaps sea spiders

42. Cheliceriforms have body w. cephalothorax & abdomen - no antennae, but most have simple eyes - 6 pairs of appendages start w. pedipalps – sensory, feeding & reproduction - then chelicerae & 4 pairs of walking legs - respiration using book lungs