Presentation on theme: "Kingdom Animalia Last day… introduction to animals"— Presentation transcript:
1Kingdom AnimaliaLast day…introduction to animals& their characteristics
2…covered early branches the Porifera (prob. monophyletic),Ctenophora & Cnidaria, theAcoela, and started theLophotrochozoa
3Began looking at phylum Platyhelminthes – the Flatworms - ~20,000 spp.?- also acoeolomate & triploblastic, but usually more complexthan Acoela
4covered Class Turbellaria… - mostly free-living, marine, a few freshwater- glide or swim- reproduce by fission, or sexual reproduction byhermaphrodites~3,000 spp.
5Class Monogenea – monogeneans - external parasites of fish (or hippo) with relatively simplelife cycles3 or 4,000 described? but may be about one per fish species, so almost 25,000?
6Class 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 enzymes18,000 to 24,000 spp. (if latter, Platyhelminthes much more than 20,000 spp.)Fasciolopsisintestinal fluke
7Have 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 orbladder veins, affects 200 million people
8Class Cestoda – tapeworms - specialized parasites, mostly of vertebrates (including us)- scolex (‘head’) w. suckers & sometimes hooks to attach inintestines- no mouth or digestive system, justabsorb nutrients- long ‘body’ of proglottids, mostlycontain sex organs, detach &pass out in feces>1000 spp.
9Phylum 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. alimentarycanal w. mouth & anus, ‘jaws’ for grinding- has pseudocoelom- one class reproduces via unfertilized eggs producing onlyfemales, apparently for > 35 million years?
10The lophophorates: 3 phyla actually have lophophores: crown of ciliated tentacles, draws water & food in- these phyla sessile, lack definite head, have U-shapedalimentary tract & true coelom
11We 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 somefreshwater spp. (9 in IL)Pectinatellamagnifica
12Phylum 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.), butabundant in Palaeozoic
13Move 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 basicbody plan: shell-secreting mantle covers visceral mass(w. major organs), foot for locomotion, digging)- mantle cavity houses gills, anus, etc.
14Eight? 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 rocksabout 1000 spp.
15Class Gastropoda – snails and slugs - marine (most), fresh-water or terrestrial, by far the largestclass (about 70,000 species)- head present, eyes on tentacles- terrestrial snails lack gills, respire through lining ofmantle cavityabout 70,000 spp.
16- embryo undergoes torsion during development: body twists up to 180°, bringing anus & mantle cavity over head- distinct from coiling of shell
17Most 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
18Class Bivalvia – clams, oysters, mussels, scallops… - shell with 2 halves, hinged mid-dorsally (so a leftvalve & a right valve)
19Bivalves 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, & scallopsuse ‘jet propulsion’ by rapidly opening/closing shell
20- some bivalveshave eyes &sensory tentaclesat edge of mantle- giant clams mayweigh > 220 kg,colorful due toalgal symbionts
21Class Cephalapoda – squids, octopuses, nautiluses - active predators with tentacles to grab prey, beak to bite &toxic saliva- well developed eyes, and regarded as very intelligent forinvertebrates- jet propulsion from siphonabout 800 spp.
22Chambered nautiluses have shell, but shell reduced & internal in squids, often absent in octopuses
23Some 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 adultsestimated to reach 14 m- more robust body, relatively shorter tentacles, so weightat least 495 kg
25Last of the lophotrochozoans… Phylum Annelida – segmented worms (‘little rings’)- 16,500 spp. in marine, freshwater & damp soil habitats- divided into 2 classes?
26Class Oligochaeta – Earthworms - bristles or chaetae along side are sparse (4 pairs/segment)- tunnel through soil, consuming dirt& organic material, eliminatingwaste as ‘castings’- ganglia above & belowpharynx connect toventral nerve cord- hermaphrodites, clitellumproduces ‘cocoon’ forshed eggs & sperm- some may regenerate afterfragmentationDarwin – 1 acre – 50,000 worms, 18 tons castings per yearabout 10,000 spp. ~half of phylum
27- formerly separate class, now seem to be part of Oligochaeta 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 drugabout 500 spp.?
28Class 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, somedrift or swim
29Some 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!!
31Have worked our waythrough Lophotrochozoa,sister group is the Ecdysozoa- perhaps the most successfulanimals of all?
32Ecdysozoa 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, but2 much more diversethan others…
33Phylum 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 canwithstand 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) orparasites of many species, including humans- e.g. Trichinella spiralis from raw pork causes trichinosis
35And now the big time! Phylum Arthropoda – Arthropods - by far the biggest phylum, ~2/3 of all described spp.are arthropods (~1,000,000 spp.)
36In 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 exoskeletonprotects, supports& preventsdessication- jointed appendagesfor mobility
37- exoskeleton composed of a cuticle covering entire surface, composed of chitin (a polysaccharide) & protein- provides attachment points for muscles
38Arthropods have well-developed sensory organs: eyes, simple or compound, olfactory/taste receptors,antennae for touch & smell- well cephalized- have variousorgans for gasexchange, e.g.spiracles leadingto branchedtracheal systemin insects
39Aquatic arthropods usually have gills with extensive surface area for gas exchange
40Arthropods 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 viavalved pores
414 subphyla in Arthropoda, starting w. Cheliceriformes - named for chelicerae: claw-like feeding appendages, usedas pincers or fangs- most of ~100,000 spp. are arachnids – spiders, ticks, mites,scorpions, harvestmen & sun spiders- cheliceriforms also include horseshoe crabs & perhapssea spiders
42Cheliceriforms 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- respirationusing booklungs