chapter 30 protostome animals

1. Chapter 30 PROTOSTOME ANIMALS The first bilaterally symmetrical “coelomates”

2. Summary General Characteristics Phylogeny Fossil record DNA analysis of rRNA Diversification Lophotrochozoans Ecdysozoans

4. Why Are We Interested in Protostome Animals? Food source – crustaceans, mollusks Pollinate crops, enrich soil Eat crops Carry diseases, parasites Very diverse, very abundant Important in marine and terrestrial ecosystems. Research – Drosophila & C. elegans

5. General Characteristics Embryonic development – Protostomic, Triploblasty Bilateral symmetry Segmented bodies evolve in 2 groups Soft-bodied or exoskeletons of chitin or chitin + CaCO3. i.e. Invertebrates

6. Major Evolutionary Development Coelom: ancester had a coelom however, some groups have reduced or lost the coelom, others have a pseudocoelom, (see Ch 29). Body style that developed is described as a tube within a tube.

7. Phylogeny - Fossil Record Trilobites, extinct animals that existed 450-550 mya. Segmented bodies, jointed appendages and a hard exoskeleton. Arthropods appeared about 520 mya Insects appeared about 400 mya around the time land plants proliferated.

8. Phylogeny - DNA DNA analysis of rRNA produces 2 groups Lophotrochozoa – Ecdysozoa –

10. Diversification Moved from water to land several times. Challenges were: Moving respiratory gases (O2 and CO2) in and out of the body. Prevention of desiccation – eggs and adults. Various types of movement evolved. Various eating structures evolved.

11. Lophotrochozoa Named for the feeding structure, lophophore, and larvae, trochophore, in some of the members. **Grow by adding increments to their bodies/exoskeleton or through cell growth not cell division. We will look at 4 of the 14 phyla: Rotifera, Platyhelminthes, Annelida, and Mollusca.

13. Lophotrochozoans – 4 Phyla Rotifera – rotifers, wheel animals Free-living animals found in soil, marine and fresh water. Pseudocoelom Cilia on lophophore aid in feeding & swimming. Filter feeders Asexual reproduction

14. Platyhelminthes - Flatworms Parasitic and free-living varieties No coelom, no segmentation No circulatory or respiratory system Sexual reproduction and asexual regeneration 3 classes: Turbellaria, Trematoda and Cestoda.

15. Platyhelminthes Class Turberllaria (planaria) –

16. Platyhelminthes Class Cestoda -tapeworms Endoparasites

17. Figure 30.4: Life cycle of the beef tapeworm.Figure 30.4: Life cycle of the beef tapeworm.

18. Platyhelminthes Class Trematoda (flukes) –endoparasites Life cycle involves 2 hosts - snail and vertebrate (fish and humans) Liver fluke (Clonorchis sinensis) and blood fluke (Schistosoma). (Snails and humans)

19. Annelida – segmented worms **True coelom Series of segments are separated internally by septa. Specialized segments include sensory organs and a brain anteriorly. Closed circulatory system, “beating” blood vessels Digestive tract – well-developed (pharynx, esophagus, crop, gizzard and intestine). Circular and longitudinal muscles for movement. Setae or chaetae, bristle like extensions for traction. Earthworm movement

20. Annelida – 2 classes Class Polychaeta (bristle worms) – many chaetae Some live in tubes, some are free swimmers or crawlers. Filter feeders or predators Well developed head and sense organs. Parapodia on most segments used for swimming or crawling and gas exchange.

21. Annelida – 2 classes Class Clitellata - Mucous cocoon produced for fertilized eggs (clitellum); hermaphroditic. 2 groups: Oligocheta (earthworms) – Hirudinea (leeches) –

24. Mollusca Coelom reduced or absent Digestive, excretory and reproductive systems organized in visceral mass. Locomotion via muscular foot which is also used for attachment and food capture. Distinct head in some species

25. Mollusca Mantle - membranous folds outer surface secretes a shell; inner layer encloses visceral mass. Shell - protein covered, multiple layers of CaCO3; inside many produce mother-of-pearl. Visceral mass: Gills Open circulatory system Digestive system Excretory system – tubular structures called nephridia empty wastes into mantle cavity. Gonads

27. Mollusca Feeding - Many have a rasping tongue with teeth-like structures called a radula. Most have separate sexes, some are hermaphroditic External fertilization except gastropods

28. Mollusca – 4 classes Class Polyplacophora - Chitons have 8 overlapping chitinous plates. Herbivores that graze along the floor of the ocean. Class Gastropoda - Snails, slugs, nudibranchs. Mantle and anus moved toward mouth during development – coiled shells. Herbivores and carnivores, aquatic and terrestrial.

31. Mollusca Class Bivalvia – oysters, clams, scallops and mussels. 2 shells hinged together by a ligament. Mantle often secrete mother-of-pearl inside shells. Usually sessile (marine and fresh water), filter feeders. No distinct head but scallops have “eyes” along margin of mantle.

33. Mollusca Class Cephalopoda - octopuses, squids, cuttle fish and nautiluses. Intelligent predators, foot has evolved into tentacles with suckers &/or hooks. Beak-like jaw and a radula to capture prey; Closed circulatory system Large brain and highly developed eyes. Most have no shell, use water flow through mantle to propel themselves (jet propulsion).

36. Ecdyzoans Grow by molting – shedding exoskeleton; cell size increases. Pseudocoeloms or reduced coeloms About 8 phyla – 2 representative phyla are Nematoda and Arthropoda

37. Nematoda - roundworms Pseudocoelom – hydrostatic skeleton Includes marine & fresh water varieties, soil varieties and parasites. Unsegmented Covered by thick cuticle, molting of cuticle as the animal grows. Mouth has piercing organs, stylets. As the pharynx contracts food is drawn into the digestive tract; anus for excretion.

38. Nematoda Sexual reproduction Includes hookworms, pinworms, Ascaris, etc. Diseases: anemias, trinchinosis from pork and filaria in lymph system (elephantiasis).

40. Arthropoda **Development of jointed appendages and exoskeleton. Appendages include legs, antennae, mouthparts & wings. Earth’s most successful animals Responsible for pollination of many crops Cause destruction of human food sources, and are carriers of diseases. Life cycle – metamorphosis (2 types)

41. Arthropoda Segmented body parts, usually fewer than annelids, some are fused. Distinct head Molting of exoskeleton Compound eyes, ommatidia, and simple eyes, ocelli.

42. Arthropoda Open circulatory system, simple heart Nervous system – brain + ganglia Respiratory system – air ducts, tracheae that branch into tracheoles throughout body, openings to the outside are called spiracles. Excretory system – Malpighian tubules reabsorb water, etc. and remove waste by secretion.

43. Arthropoda – S.P. Crustacea Crabs, shrimp, crayfish, lobster, barnacles, pill bugs, etc. Body has 2 regions, cephalothorax and abdomen 2 pair of antennae, 3 types of chewing appendages (biting mandibles), various numbers of legs. Gills or simple diffusion of gases Most have separate sexes, internal fertilization

46. Arthropoda – S.P. Chelicerata Class Meristomata - horseshoe crabs. Class Arachnida - spiders, tarantulas, scorpions, mites and ticks. Terrestrial (silken webs) or marine Appendages: Paired fangs or pincers for feeding chelicerae Paired pedipalps (used for copulation or develop into pincers), 4 pair of legs. Book lungs –

48. Arthropods – S.P. Myriapoda Classes Chilopoda (centipedes) and Diplopoda (millipedes) Trachea for gas exchange Malpighian tubules for excretion of wastes. Head and numerous body segments, each with paired appendages, 1 pair/segment in centipedes and 2 pair in millipedes. Internal fertilization, lay eggs Centipedes are carnivores, millipedes are herbivores.

50. Arthropoda – S.P. Insecta Largest, most successful group Live everywhere, mostly terrestrial but some have invaded fresh and salt water. *3 body sections: head, thorax, and abdomen. 3 pair of legs on the thorax and 1 pair of antennae Compound and simple eyes

52. Arthropoda – S.P. Insecta 2 pair of wings, 1 pair may be modified, some have no wings Mouthparts – 4 pair are modified for type of feeding. Larvae are wormlike (caterpillars) Movement – swim, fly, walk or run. 10 major Orders of insects

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