1. Chapter 25 Worms & Mollusks

2. 25-1 FLATWORMS

3. Flatworms Phylum Platyhelminthes –Acoelomates –Thin, solid bodies –Bilateral symmetry –Found in marine, freshwater, and moist habitats on land –Examples: tapeworms, flukes, and planarians

4. Feeding and Digestion in Planarians Feed on dead or slow moving organisms It extends the pharynx out of its mouth Enzymes digest the food outside of the body Food is sucked into pharynx

5. Planarians Head – senses and responds to the environment Eyespots – sensitive to light Sensory pits – used to detect food, chemicals, and movements in the environment Pharynx – muscular tube that extends outside the body to digest food Cilia – underneath, help with moving the planarian Flame cells – helps to remove water from the planarian’s body

6. Eyespot Head Digestive Cavity Nerve chord

7. Nervous Control in Planarians Some have a nerve net and others have a simple central nervous system Ganglia receive messages from the eyespots and sensory pits and then communicates with the rest of the body through nerve cords

8. Reproduction in Planarians Asexually, they regenerate body parts by mitosis Most are hermaphrodites Sexually- two flatworms exchange sperm to fertilize eggs internally Zygotes are released in capsules into water

9. Diversity of Flatworms Planarians are free-living Tapeworms and flukes are parasites which live in many vertebrates (dogs, cats, cows, humans, etc.) Fluke Tapeworm

12. Feeding and Digestion in Parasitic Flatworms Parasites live on or in another organism and depends on it for food Have mouthparts with hooks to attach to host They do not have a complex nervous system, muscular tissue, or digestive organs because they are surrounded by nutrients

13. Tapeworm bodies have sections The body is made of a head and repeating sections called proglottids Scolex – head Proglottid – contains muscles, nerves, flame cells, and reproductive organs

14. The Life Cycle of a Fluke

15. Adults live in blood vessels Fluke eggs pass out of body in waste product Eggs hatch into free-swimming larvae and enter the snail host Larvae develop and reproduce in the snail and then leave the snail When humans walk in water, the flukes bore through the skin and enter the bloodstream and into the intestines

16. Fluke Life Cycle

30. Beautiful Flatworms

31. Marine Flatworms of Japan

32. Flatworms from Maldives

33. Flatworms from the Red Seas

34. Flatworms from the Philippines and Thailand

36. Flatworms from Australia and Fiji

37. Flatworms from Hawaii and Pacific Coast

38. From Atlantic Ocean

39. From East Asia

45. Chapter 25.2 Roundworms and Rotifers

46. Roundworms Phylum Nematoda –Live in soil, animals, freshwater, and saltwater –Most are free-living, but some are parasitic –Tapered at both ends –Thick outer coverings –Have longitudinal muscles to make the worm move back and forth –Pseudocoelomate –Two openings: a mouth and anus

48. Nematode- roundworm Two Roundworms Reproducing 

49. Roundworm Diversity Ascaris infect mostly children who put soil into their mouths or eat veggies that are not cleaned –Intestines to bloodstream to lungs Hookworms infect humans walking barefoot in warm climates –Cause weakness due to blood loss

50. Ascaris Ascaris (Intestinal Roundworm)- These nematodes are found exclusively in humans and are present mostly in unsanitary areas without modern plumbing. Around one in six people worldwide are infected by Ascaris (Raven et al. 746). A study conducted in Cameroon focused on school children and found that 65.5 % were infected with Ascaris parasitic roundworms. Ascaris eggs are spread through feces, and, when ingested, hatch and bore through the intestinal wall. They move to the heart, the lungs, and finally out the breathing passages where they are swallowed, thus perpetuating the cycle. Females lay hundreds of thousands of eggs each day and can reach nearly 30 centimeters in length (Raven et al. 746).

51. Hookworms Researchers have long noted that humans in tropical areas known to be hookworm hotbeds have much lower rates of allergies. Recent research also suggests that hookworms may indeed prevent allergy attacks. The speculation is that in an absence of such parasites, people's immune systems have essentially too much time on their hands, causing the disproportionate and inappropriate immuno- responses that result in allergies. The hookworms must avoid detection in order to survive and thus "damp down" humans' immune systems with proteins.

52. Roundworm Diversity Pinworms infect children that eat things that came from contaminated soil –Females lay eggs near anus, leading to itching and infection Trichinella cause trichinosis and enter the body through undercooked pork

53. Pinworms

54. Roundworm Diversity Filarial worms cause Elephantiasis and heart worms. Carried by mosquito Elephantiasis

55. Nematodes as Parasites o Many Nematodes are decomposers, but a lot are parasites, such as heartworms. Humans host about 50 species of nematodes. Many infect insects and on plants.

56. Guinea Worm The guinea worm is a parasitic nematode that causes Guinea Worm Disease, or Dracunculiasis. Carried by water fleas. Only females survive. Can take 2 months to remove one. People can have up to 60 worms. Preventable by having clean drinking water.

57. Roundworm Diversity Nematodes infect other organisms besides humans –Trees, cereal crops, food crops, and fungi Pinewood nematode

59. Phylum Rotifera “Wheel-bearer”

60. Phylum Rotifera pseudocoelomate aquatic and microscopic males are rare and even unknown in some species Parthenogenesis- female rotifers produce diploid eggs that do not need fertilization cilia located near the mouth aid in locomotion complete digestive system with mouth, intestine and anus

61. Rotifers

62. Chapter 25.3 Mollusks

64. Phylum Molluska Coelomates Bilateral symmetry Protostomes Digestive tract with two openings Muscular foot Mantle

65. Mollusk Feeding and Digestion Radula- Tonguelike organ with rows of teeth that scrapes food into mouth. Scrape algea off rocks Tear live prey apart Drill into shells of prey Both mouth and anus Complete gut: Digestive glands, stomach, intestines

66. Mollusk Respiration Gills- made of filamentous projections from the mantle filled with blood to diffuse gases. Land snails and slugs use the lining of their mantles to get oxygen from the air.

67. Mollusk Circulation Open circulatory system - Blood is pumped from vessels to open spaces around organs. Slow moving organisms (snails and clams). Closed circulatory system - Blood confined to vessels that deliver oxygen where it is needed. Faster moving organisms (squid and octopus)

68. Mollusk Excretion Nephridium- filters waste from blood Waste leaves through the mantle cavity

69. Mollusk Nervous Systems Nervous system Some have a brain –Octopus Some have eyes –Octopus –Squid

70. Mollusk Movement Muscular foot- clams use to burrow in sand Some bivalves can clap shells together to swim Siphon- Expels water from the mantle to “jet-propel” through the water Snails glide over a mucus trail with muscle contractions

71. Mollusk Reproduction Sexually- aquatic male and females release egg and sperm into the water for external fertilization. Land mollusks are usually hermaphrodites with internal fertilization. Trochophore- Larval stage of most mollusks

72. Phylum Mollusca 1. Gastropods 2. Bivalves 3. Cephalopods

73. 1. Class Gastropoda “Stomach-foot” Large foot under the stomach Single shell- snail, conch, periwinkle Thick mucus covers bodies- nudibranches, slugs

75. abalone

76. Giant African Land Snail

81. 2. Class Bivalvia Two-Shells Filter feed Moves slowly Includes clams, mussels, oysters, and scallops

82. Clam! Oyster! Scallop! Mussels!

86. And scallops have creepy eyes.

87. 3. Class Cephalopoda “Head-foot” Fast Foot= arms/tentacles with suckers Include: Squid, octopus, nautilus, cuttlefish

88. 3. Class Cephalopoda

92. Cuttlefish

97. Octopus larva

102. Useful Mollusks Vs. Harmful Mollusks Filter water to clean ecosystem Shells collected for their beauty Pearls from oysters Snail venom used to treat depression, Alzheimer's, epilepsy, heart disease Shipworms burrow into boat wood Slugs eat garden plants

103. Chapter 25.4 Segmented Worms

104. Phylum Annelida Protostomes Segmented body divided by walls of tissue Closed circulatory system Coelomates Bilateral symmetry Two body openings

105. Annelid Feeding and Digestion Eat food/soil Mouth  Crop  Gizzard  Intestine  Anus Some parasites can store enough food to last for months.

106. Annelid Circulation Closed circulatory system Enlarged vessels near the head are used to pump blood like a heart

107. Annelid Respiration and Excretion Land annelids breath through skin Aquatic annelids have gills Segmented worms have two nephridia per segment to collect and export waste

108. Annelid Nervous System Brain Nerve chords made of ganglia (group of nerve tissue) Can detect light and vibrations

109. Annelid Movement First- Contracts circular muscles to lengthen segments. Second- Contracts longitudinal muscles to shorten segments, pulling the posterior segments forward. Setae- Bristles that anchor the worm in the soil during movement.

110. Annelid Reproduction Asexually- fragmentation, some worms can regenerate missing pieces. Sexually- hermaphrodites, they exchange sperm between clitellum segments Young develop in a cocoon.

111. Phylum Annelida 1.Class Oligochaeta 1.Earthworms 2.Class Polychaeta 1.Polychaetes 3.Class Hirudinea 1.Leeches

112. 1. Earthworms: Class Oligochaeta Eat their own mass in soil per day Aerate the soil by tunneling Live for about two years Come to the earth’s surface when it rains to find a mate while the ground is damp and it is easier to move. Compost organic waste

114. 2. Class Polychaeta Bristleworm and Fan Worm Marine animals Have eyes Fan worms are sessile filter feeders that retreat into their tube if disturbed.

116. 3. Leeches: Class Hirudinea Parasite Live in fresh water Front and rear suckers Can be used after surgery to prevent blood clotting and drain blood that has pooled Saliva contains anesthesia –Anesthesia: Prevents any pain –Anticoagulants: Prevents blood clots