1. Marine Worms
Chapter 8

2. Platyhelminthes Flatworm Bodies are flat Fresh and salt water species
Microscopic  20 meters long
More than 10,000 species

3. Planarian Fresh water and marine habitats Microscopic
Bilateral symmetry
3 cell layers
Two way digestive tract
Feed on small organisms and organic debris

4. Planarian, cont… Eyespots on head region Surrounded by ganglia
Nerve cell dusters
Act like a simple brain—send nerve impulses along 2 ventral nerve cords.

5. Planarian, cont… Locomotion Reproduction Contracts body muscles
Cilia move backward—planarian moves forward along surface of substrate.
Asexual—regeneration
Sexual—hermaphrodites

6. Planarian Reproduction
Asexual
Sexual
Attaches to a substrate—stretches its body—breaks in half.
Two flatworms exchange sperm
The sperm fertilizes the eggs of the opposite flatworm internally
External development in tiny capsules/cocoons
Hatch in 2-3 weeks

7. Ribbon Worm Largest free-living worm in the sea Phylum Nemertea
Approximately 1000 species
Average 1 meter long but can grow up to meters
Milky color
Thin and flat

8. Ribbon Worm, cont… Probiscis
Simple closed circulatory system for distribution of nutrients and oxygen
Live in intertidal zone/inside clam and oyster shells
Burrow in sand
Swim among animals that live encrusted on rocks.

9. Ribbon Worm Reproduction
Asexual
Sexual
Break into pieces
Each piece regenerates
External fertilization
External development

10. Tapeworm
Parasite
Intestines of fish and other animals
Attaches itself to the intestinal lining of its host and absorbs nutrients through its thin body wall.
No need for a digestive system

11. Trematode
Fluke
Lives in the bodies of mollusks, fish, birds, and other animals
Liver fluke-parasite in mammals
Blood fluke-skin of a fish—forms a cyst and lives in tissues

12. Trematode
Accidentally eaten in raw fish—reproduce in the digestive tracts of people
Swimmers itch—caused by Trematode attaching to human skin.

13. Phylum Nematoda Cylindrical body shape Tapered at both ends.
Range in size up to 1 meter
Example: Roundworms
The most numerous of all worms in the sea.
More than 10,000 species
Live in sand and mud at bottom of water column
Intertidal zone
Gravel of aquarium tanks.

14. Roundworms Male and female Some are hermaphrodites
Internal fertilization
External development of eggs
Males and females differ in size and shape

15. Roundworms cont… One way digestive tract Feed on organic debris
No circulatory or digestive system
Nutrients diffuse into cells—gases and wastes pass through skin
Some are parasitic
Trichina
Hookworm
Ascaris
All of the above cause diseases in humans

16. Annelida Segmented worms Body is divided into compartments
Typically found in soil and other moist sediments
“little rings”
Three classes of annelids

17. Oligochaeta
“few bristles
Earthworms

18. Polychaeta “many bristles Sandworm
Crawl around on the bottom and prey on tiny invertebrates
Burrow in the sand and scavenge on organic debris (low tide)

19. Sandworm cont… Probiscis Two sharp hooks located in its mouth
One way digestive tract
Coelem
Fluid filled space that separates the digestive tract

20. Sandworms cont… Locomotion: Parapodia Setae
Paddle like appendages located on each segment
Helps them wriggle through wet sand
Setae
Hair like bristles on each parapodium
Nervous system
Eyelike receptors
Touch receptors
Impulses to ventral nerve cord
Ganglia
Breathe through their skin
Oxygen diffuses in
CO2 diffuses out
Nephridia-excretory system (like kidneys)

21. Sandworm Reproduction Closed circulatory system Sexual
Dorsal blood vessel contracts and pumps blood
Arteries and veins carry the blood back and forth
Capillaries connect arteries with veins
Reproduction
Sexual
Not hermaphrodites like earthworms

22. The Bloodworm Polychaete Open circulatory system
Blood circulates through the tissue spaces rather than through blood vessels.
Can see blood through its skin

23. Bloodworm, cont…
Usually burrow in sand and hide in seaweed to avoid predators
Some live inside a tube which they make themselves to avoid being eaten

24. Class Hirudinea Leech Some are free living Some are parasites
Two suckers at the anterior and posterior ends
Sharp teeth at anterior end pierce host’s skin
Hirudin-chemical anticoagulant secreted into host’s wound
Prevents clotting

25. Parchment worm Secretes a tube formed from a tough fibrous material
Lies buried in sediments below low tide

26. Trumpet worm Tube looks like an ice-cream cone
Made of sand grain and bits of shell cemented together

27. Atlantic tubeworm Secretes a hard tube composed of calcium carbonate
Cemented to surfaces of mollusks, rocks, and corals.

28. Phylum Pogonophora Giant Tube Worms
New species discovered in 1977 near hot water vents on ocean floor
First photographed by submersible Alvin
Measure up to 1 meter

29. Giant Tube Worms Water is rich in hydrogen sulfide
Live in tubes made of proteins and minerals (up to 2m long)
Symbiotic relationship with bacteria

30. Chemosynthesis
The process by which the bacteria produce energy rich compounds from inorganic chemicals
Bacteria us hydrogen from H2S and combine with CO2 from sea water to produce sugars
Worms survive by using the carbs

31. Phylum Chaetognatha Arrow worm Live near the surface
Tiny and transparent
A few cm long

32. Arrow Worm: nervous system
Simple
Respond to stimuli
2 eyes in head region respond to light
Papillae
Sensory projections located on the surface of worms body
Ganglia in head and trunk region

33. Arrow worms cont… Digestion Locomotion Mostly drift with plankton
1-way digestive tract
Food is digested in narrow intestine
Waste eliminated through anus
Nutrients diffuse into cells
Mouth bristles modified as hooks
Eat copepods, fish eggs, and fish larvae
Mostly drift with plankton
Tiny fins that enable swimming

34. Arrow worms: reproduction
Hermaphrodites
Sexual reproduction
Not self-fertilization
Sperm and egg are shed into water
Sperm from one arrow worm fertilizes the eggs of another.