Platyzoans Phylum Platyhelminthes

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1 PROTOSTOMES

2 Micrognathozoa Rotifera Cycliophora Platyhelminthes Brachiopoda Bryozoa Annelida Mollusca Nemertea Loricifera Kinorhyncha Nematoda Tardigrada Arthropoda Onychophora Chaetognatha Echinodermata Chordata Platyzoans Phylum Platyhelminthes Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Protostomes Platyzoa Spiralia Lophotrochozoa Ecdysozoa 2

Flatworms Flatworms are ciliated, soft-bodied animals Bodies are solid aside from an incomplete digestive cavity Many species are parasitic Others are free-living

3 Flatworms Flatworms are ciliated, soft-bodied animals Bodies are solid aside from an incomplete digestive cavity Many species are parasitic Others are free-living Marine, freshwater, moist terrestrial Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Tom Adams/Visuals Unlimited 10 mm 3

4 Only one opening to digestive cavity Muscular contractions in the pharynx allows food to be ingested and torn into small bits Lack circulatory system Diffusion for gas transport Gut functions in digestion and food distribution Some particles digested extracellularly Cells engulf particles by phagocytosis Tapeworms (parasitic flatworms) lack digestive systems absorb food directly through body walls 4

5 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Eyespot Mouth Protruding pharynx Oviduct Sperm duct Testis Circular muscles Longitudinal muscles Parenchymal muscle Nerve cord Intestine Epidermis 5

6 Excretory System Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nervous System Reproductive System Anterior cerebral ganglion Ovary Intestine Testis Nerve cord 6

7 Have an excretory and osmoregulatory system Network of fine tubules runs through body Flame cells located on the side branches Flagella move water and excretory substances into the tubules and then to pores located between the epidermal cells through which the liquid is expelled Metabolic wastes are excreted into the gut and eliminated through the mouth 7

8 Simple nervous system Anterior cerebral ganglion and nerve cords Eyespot can distinguish light from dark Reproduction Most are hermaphroditic Undergo sexual reproduction Also have capacity for asexual regeneration 8

9 2 major groups of flatworms Free-living Turbellaria Probably not monophyletic Dugesia common planarian in bio labs Parasitic Neodermata Trematoda flukes Attach within host body by suckers, anchors, or hooks Life cycle may have 2 or more hosts Clonorchis sinensis, oriental liver fluke Cercomeromorpha tapeworms 9

10 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Metacercarial cysts in fish muscle Metacercariae are consumed by humans or other mammals Liver Bile duct Cercaria Redia Sporocyst Miracidium hatches after being eaten by snail Adult fluke Egg containing miracidium in feces (into water) 57 µm Dwight R. Kuhn 10

11 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 125 µm The Natural History Museum/Alamy One of most important trematodes to human health are blood flukes Schistosoma Afflict 5% of world s population About 800,000 people die each year from schistosomiasis or bilharzia Fertilized egg must break through the wall of the blood vessels in intestine or the urinary bladder to get out 11

12 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Dennis Kunkel/Phototake 500 µm Cercomeromorpha tapeworms Adult hangs onto inner wall of host intestine using scolex 12

Hooks Scolex attached to intestinal wall Uterus Genital pore Sucker

Complete hermaphroditic unit, containing both male and female

13 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Hooks Scolex attached to intestinal wall Uterus Genital pore Sucker Proglottids Proglottid Scolex Most of tapeworm body is proglottids Complete hermaphroditic unit, containing both male and female reproductive organs Formed continuously Beef tapeworm, Taenia saginata Frequent human parasite From eating uninspected rare beef 13

14 Micrognathozoa Rotifera Cycliophora Platyhelminthe s Brachiopoda Bryozoa Annelida Mollusca Nemertea Loricifera Kinorhyncha Nematoda Tardigrada Arthropoda Onychophora Chaetognatha Echinodermata Chordata LOPHOTROCHOZOANS PHYLUM MOLLUSCA Second in diversity only to arthropods Include snails, slugs, clams, octopuses and others Some have a shell, some do not Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Protostomes Platyzoa Spiralia Lophotrochozoa Ecdysozoa 14

15 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a. b. c. d. a: Marty Snyderman/Visuals Unlimited; b: Alex Kerstitch/Visuals Unlimited; c: Douglas Faulkner/Photo Researchers, Inc.; d: agefotostock/superstock 15

Range in size from microscopic to huge Giant clams may weigh 270 kg Evolved in the oceans, and most groups have remained there Important source of human food

16 Range in size from microscopic to huge Giant clams may weigh 270 kg Evolved in the oceans, and most groups have remained there Important source of human food Economically significant in other ways Pearls are produced in oysters Mother-of-pearl is produced in the shells of abalone Pests Zebra mussel (Dreissena polymorpha) 16

17 MOLLUSK BODY PLAN Mantle Thick epidermal sheet Bounds mantle cavity Secrete shell (if there is one) Foot Primary means of locomotion for many Divided into arms or tentacles in cephalopods 17

18 Internal organs Coelom is highly reduced Limited to small spaces around the excretory organs, heart, and part of the intestine Digestive, excretory, and reproductive organs are concentrated in a visceral mass Ctenidia gills in aquatic mollusks Also filter food in most bivalves 18

19 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chitons Mantle Shell Gut Radula Gill Foot Gastropods Shell Gut Lung Antenna Foot Radula 19

20 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Bivalves Gut Shell Foot Adductor muscle Gill Siphons Mantle Gut Cephalopods Siphon Tentacle Mantle cavity Gill Eye Arm 20

21 Shell Protects against predators and adverse environments Secreted by outer surface of mantle Clearly not essential repeated loss or reduction Typical shell has 2 layers of calcium carbonate Internal layer may be mother-of-pearl or nacre Pearls are formed by coating foreign object with nacre to reduce irritation 21

22 Radula Characteristic of most mollusks Rasping, tonguelike structure used in feeding Used to scrape up algae In predatory gastropods, modified to drill through clam shells In Conus snails, modifies into harpoon with venom gland Bivalves do not have a radula Gills used in filter feeding 22

23 Esophagus Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Radula tooth Muscles Mouth Mouth Radula Bottom: Eye of Science/Photo Researchers, Inc. 25 µm 23

24 Nitrogenous waste removal nephridia Consist of cilia-lined openings called nephrostomes Tube to excretory pore to mantle cavity Circulatory system Open circulatory system Hemolymph sloshes around hemocoel 3-chambered heart Cephalopods have a closed circulatory system 24

25 MOLLUSK REPRODUCTION Most mollusks are gonochoric A few are hermaphroditic Some oysters change sex Most engage in external fertilization Gastropods have internal fertilization Mollusk zygote undergoes spiral cleavage 25

26 CLASSES OF MOLLUSKS There are 7 or 8 recognized classes 1. Polyplacophora chitons 2. Gastropoda limpets, snails, slugs 3. Bivalvia clams, oysters, scallops 4. Cephalopoda squids, octopuses, cuttlefishes, and chambered nautilus 26

27 Micrognathozoa Rotifera Cycliophora Platyhelminthes Brachiopoda Bryozoa Annelida Mollusca Nemertea Loricifera Kinorhyncha Nematoda Tardigrada Arthropoda Onychophora Chaetognatha Echinodermata Chordata LOPHOTROCHOZOANS NEMERTEA About 900 species of cylindrical to flattened very long worms Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Protostomes Platyzoa Spiralia Lophotrochozoa Ecdysozoa 27

28 Most are marine; a few species live in fresh water and humid terrestrial habitats Lineus longissimus has been reported to measure 60 m in length the longest animal known! Body plan resembles a flatworm Has a complete gut Rhynchocoel fluid filled coleomic cavity 28

29 Gonochoric with sexual reproduction Asexual reproduction through fragmentation Belong to lophotrochozoans because Blood flows entirely in vessels Rhynchocoel 29

Micrognathozoa Rotifera Cycliophora Platyhelminthes Brachiopoda Bryozoa Annelida Mollusca Nemertea Loricifera Kinorhyncha Nematoda Tardigrada Arthropoda Onychophora Chaetognatha Echinodermata

30 Micrognathozoa Rotifera Cycliophora Platyhelminthes Brachiopoda Bryozoa Annelida Mollusca Nemertea Loricifera Kinorhyncha Nematoda Tardigrada Arthropoda Onychophora Chaetognatha Echinodermata Chordata LOPHOTROCHOZOA NSPHYLUM ANNELIDA Segmented worms Body built of repeated units Allows for specialization May not be monophyletic Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Protostomes Spiralia Ecdysozoa Platyzoa Lophotrochozoa 30

31 Body plan Head has well-developed cerebral ganglion Sensory organs in ringlike segments Many species have eyes Segments divided internally by septa Each segment has a pair of excretory organs, a ganglion, and locomotory structure Closed circulatory system Ventral nerve cord 31

32 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Setae Segments Esophagus Pharynx Mouth Brain Clitellum Hearts Male gonads Female gonads Dorsal blood vessel Septa Nerve cord Ventral blood vessel Intestine Nephridium 32

33 Each part of digestive tract specialized for different function Locomotion Coelomic fluid creates a hydrostatic skeleton Alternating muscle contractions allows complex movements Chaetae bristles of chitin found in most groups Closed circulatory system Gas exchange by diffusion across body surfaces Excretory system nephridia similar to mollusks 33

34 Roughly 12,000 described species of annelids occur in many habitats 2 classes 1. Class Polychaeta Monophyly not well established 2. Class Clitella Oligochaeta Hirudinea 34

35 Micrognathozoa Rotifera Cycliophora Platyhelminthes Brachiopoda Bryozoa Annelida Mollusca Nemertea Loricifera Kinorhyncha Nematoda Tardigrada Arthropoda Onychophora Chaetognatha Echinodermata Chordata Phylum Nematoda Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Protostomes Platyzoa Spiralia Lophotrochozoa Ecdysozoa 35

Vinegar eels, eelworms, and other roundworms Members of this phylum are found everywhere abundant and diverse Marine, freshwater, parasites, free-living

36 Vinegar eels, eelworms, and other roundworms Members of this phylum are found everywhere abundant and diverse Marine, freshwater, parasites, free-living Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Educational Images Ltd., Elmira, NY, USA. Used by Permission 181.1µm 36

37 Bilaterally symmetrical and unsegmented Covered by a flexible, thick cuticle that is molted as they grow Digestive system well developed Stylets piercing organs near mouth Pharynx creates sucking action Anus 37

38 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Mouth Testis Excretory pore Pharynx Dorsal nerve cord Muscle Intestine Anus Spicules Pseudocoelom Genital pore Excretory duct Intestine Testis Epidermis Ventral nerve cord Cuticle 38

39 Sexual reproduction Most gonochoric Sexual dimorphism male smaller with hooked end Internal fertilization Indirect development egg, larva, adult Eutely Adults consist of a fixed number of cells Caenorhabditis elegans has only 959 cells Important in genetic and developmental studies 39

40 Lifestyles Many are active hunters, preying on protists and other small animals Others are parasites of plants Still others live within the bodies of larger animals Largest known nematode, which can attain a length of 9 m, parasitizes the placenta of sperm whales 40

41 About 50 species cause human diseases Hookworms Common in southern U.S. Produce anemia Trichinella causes trichinosis Forms cysts in muscles Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Infection from eating undercooked meat Gary D. Gaugler/Photo Researchers, Inc. 50 µm 41

42 Pinworms, Enterobius vermicularis Infects 30% of children in U.S. Causes itching of the anus Ascaris lumbricoides intestinal roundworm Infects 1 in 6 worldwide Adult female can be 30 cm long Rare in areas with modern plumbing Serious tropical nematode diseases Filariasis Elephantiasis 42

43 Micrognathozoa Rotifera Cycliophora Platyhelminthes Brachiopoda Bryozoa Annelida Mollusca Nemertea Loricifera Kinorhyncha Nematoda Tardigrada Arthropoda Onychophora Chaetognatha Echinodermata Chordata ARTHROPODA Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Protostomes Platyzoa Spiralia Lophotrochozoa Ecdysozoa 43

44 By far the most successful animals Well over 1,000,000 species (2/3 of all named species) Arthropods affect all aspects of human life Divided into four extant classes Chelicerata Crustacea Hexapoda Myriapoda 44

45 45

Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 36.2% Beetles 12.1% Other arthropods 12.1% Flies 12.1% Butterflies, moths 10.3% Bees, wasps, ants 8.

46 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 36.2% Beetles 12.1% Other arthropods 12.1% Flies 12.1% Butterflies, moths 10.3% Bees, wasps, ants 8.6% Other insects 3.4% Crustaceans 5.2% Arachnids Arthropods are a successful group About two-thirds of all named species are arthropods. About 80% of all arthropods are insects, and about half of the named species of insects are beetles 46

47 ARTHROPOD MORPHOLOGY Part of arthropod success explained by 1. Segmentation In some classes specialized into tagmata Head, thorax, abdomen Head and thorax may be fused into cephalothorax or prosoma 2. Exoskeleton Made of chitin and protein Protects against water loss Must undergo ecdysis molting 47

48 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Compound eye Antenna Head Thorax Air sac Malpighian tubules Abdomen Rectum Mouth parts Spiracles Midgut Poison sac Sting 3. Jointed appendages May be modified into antennae, mouthparts, or wings Can be extended and retracted 48

49 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Open circulatory system Nervous system Double chain of segmented ganglia Ventral ganglia control most activities Can eat, move, or copulate with brain removed Ocellus Compound eye a. Brain Head Thorax Abdomen Antennae Tympanum Aorta Stomach Ovary Spiracles Heart Rectum Mouth Crop Gastric ceca Malpighian tubules Nerve ganglia b. 49

50 Compound eyes are found in many arthropods Composed of independent visual units called ommatidia Other arthropods have simple eyes, or ocelli May be in addition to compound eyes Have single lenses Distinguish light from darkness 50

51 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Ommatidium Corneal lens Compound Eye Crystalline cone Rhabdom Retinular cells Pigment cell Ommatidium Optic nerve Nervefiber 51

52 Respiratory system Many marine arthropods have gills Some tiny arthropods lack any structure for gas exchange Terrestrial arthropods use tracheae Branch into tracheoles in direct contact with cells Connected to the exterior by spiracles Valves control water loss Many spiders use book lungs Leaflike plates 52

53 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Tracheoles Trachea Spiracles Spiracles 53

Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Brain Aorta Stomach Ovary Heart Rectum Mouth Crop Gastric ceca Malpighian tubules Nerve ganglia b.

54 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Brain Aorta Stomach Ovary Heart Rectum Mouth Crop Gastric ceca Malpighian tubules Nerve ganglia b. Excretory system In aquatic arthropods much of the waste diffuses out of gills Terrestrial insects and some others use Malpighian tubules Eliminates nitrogenous wastes as concentrated uric acid or guanine Efficient conservation of water 54

Phylum: Porifera (sponges)

Phylum: Porifera (sponges) (8,761 known species) General Description: Simplest animals, multicellular No organs or body systems Skeleton composed of spongin (soft) and spicules (hard) Symmetry: Asymmetrical