1. Chapter 1: Invertebrates I: Sponges, Jellyfish, and Worms
Unit 1: Concepts in the Animal Kingdom
Chapter 1: Invertebrates I: Sponges, Jellyfish, and Worms

2. Introduction Over one million animal species Animal Multi-cellular
Tissues
Must obtain food rather than make own
Most
can move at some point in life cycle
Eat food
Have organs
Reproduce sexually

3. What is an Invertebrate?
Invertebrate: animal without a backbone
Most animal species are invertebrates
Skeleton: provides mechanical support and body shape
Invertebrates have skeletons; often not internal skeletons made of bone
Internal skeleton may be like: limestone, glass, protein, water

4. Sponges Sponges: “pore” animals—body made up of pores
Phylum named: Poriferia
Characteristics:
All live in water
Most live in oceans
Only a few live in fresh water
Adults unable to move—young sponges able to swim
Made of spongin—fibrous protein, pointed spicules—calcium carbonate, or silica
Some used as bath sponges

5. How a sponge eats: Filter feeders: filter water to absorb food
Water enters pores of sponge
Jellylike layer between outer and inner layer distributes nutrients in the sponge
Water enters hollow central cavity of sponge
Collar cells line the cavity; the flagella on the collar cells keep the water moving
Water exist through large opening at top of sponge

8. Cnidarian—Jellyfish Jelly-like mass 2 Layers of tissues
Hydrostatic skeleton: skeleton surrounded by water
Most live in oceans
Few found in freshwater
Large central cavity surrounded by two tissues
Tentacles

9. Jellyfish
2 Layers
Ectoderm and Endoderm each one layer thick
Gastrovascular cavity: used by the jellyfish to digest food
Mouth: only body opening; food goes in/waste comes out
Network of nerves
No brain or collection of nerves
Some muscle fibers controlled by nerves

10. Jellyfish Activities Tentacles have nematocysts (stinging cells)
Stinging cell penetrates prey and poison is forced through thin tube
Prey is paralyzed or killed
Jellyfish uses tentacles to bring food to mouth
Food digests in gastrovascular cavity/waste is expelled

11. Jellyfish Activities Tentacles not used for swimming
Jellyfish mostly float around
To swim
Fish contracts and forces water out of gastrovascular cavity

12. Other Cnidarias All have tentacles with stinging cells
Large central cavity surrounded by two tissue layers
Example: hydra, corals, sea anemones
Radial symmetry: several planes to divide
Shape: Tube-like or umbrella shape
Free living or permanently attached

26. The Planarian: A Type of Flatworm
Characteristics: Phylum Platyhelminthes
Bodies are flat
Bilateral symmetry
Free-living
Live: freshwater, ocean, parasites, or soil

27. The Planarian: A Type of Flatworm
Free-living
Live in freshwater streams or soil
The Planarian’s Nervous System
Neurons: long thin nerve cells found throughout the body—carry impulses from one point to another
Nerve: collection of neurons wrapped together in a protective coat
Ganglion: “simple brain” switchboard for nerves several within body—control portion

28. The Planarian: A Type of Flatworm
The Planarian Nervous System (cont.)
Longitudinal nerve—runs down each side of body
Transverse nerves—connects long. Nerves; ladder appearance
Respond to Stimuli
Stimulus—something an organism can sense
Neuron receives stimulus, converts it to impulse, impulse travels through nerve to ganglion, ganglion sends response message

29. The Planarian: A Type of Flatworm
Planarians Respond to:
Touch
Chemicals—find food in this way
Light—two spots sensitive to light—”cross-eyed” worms—usually move away from light

30. The Planarian: A Type of Flatworm
The Planarian’s Digestive System
Body of planarian one layer thick
Mouth—middle of the underside of its body
Intestine—long branched cavity
Gastroderm—cells that layer the intestine
Eating:
Extends pharynx (muscular tube) into mouth—sucks food into intestine; gastroderm secrete enzymes—digestion begins; nondigested materials exit through the mouth; intestines take nutrients to rest of body

31. The Planarian: A Type of Flatworm
Oxygen and carbon dioxide is exchanged through thin skin
Waste removed through series of tubes
Flame cells—structure at the end of the tube that move waste
Excretory pores—tiny holes that water and waste are excreted from the planarian

32. The Planarian: A Type of Flatworm
Other Interesting Flatworms
Examples: tapeworms, flukes, marine flatworms
Tapeworms: common parasite found in the digestive tract
Head has hooks or suckers to attach to wall of intestine
Most of body eventually fills with eggs and released in host animal’s waste and spread to other animals

34. These individuals were photographed on a reef near the island of Guam.

35. Copyright Marian K. Litvaitis, University of New Hampshire, 2005-2007

36. Roundworms Phylum Nematoda Round tube-like bodies
Bodies tapered at one end
Live: parasites or free-living
Many microscopic

37. Roundworms Ascaris—A common Roundworm
Parasite—lives in intestine of animals
Eggs released in intestine—exist in feces
When eggs are swallowed they hatch
Young larvae enters blood stream—reach the lungs—at throat they are reswallowed
Grow into adult worm in intestines

38. Roundworms Other Interesting Roundworms
Example: Hook worms, pinworms, trichina worms
Trichina worm found in pork
Vinegar eel found in unpasteurized cider
Other roundworms cause plant disease

39. The Earthworm and Other Segmented Worms
Phylum Annelida
Series of similar segments
Examples: earthworms, leeches, tubeworms, scale worms, clam worms, lugworms

40. The Earthworm and Other Segmented Worms
The Body of an Earthworm
Epidermis—thin skin that covers body; used for gas exchange
Cuticle—outer covering that protects worm
Two muscle layers under cuticle—provide support and movement
One layer—circles around body (long and thin)
Second layer—long strips down body (shorter and wider)
Bristles—tiny hairs on each segment that aid in movement

41. The Earthworm and Other Segmented Worms
Earthworm’s Nervous System
Sensory receptor—sense an impulse and send message along a neuron
More sensory receptors at front than back
Sensory Receptor in front —to neuron—to large ganglia in third segment
Other sensory receptors—to neurons—to nerve cord—small ganglion at each segment
Ganglia ‘interprets’ impulse and sends response message to neurons

42. The Earthworm and Other Segmented Worms
The Earthworm’s Digestive System
Earthworms eat soil as it makes tunnels
Eats decaying leaves, fungi, and small creatures in dirt
Digestive tract is long and straight

43. The Earthworm and Other Segmented Worms
Mouth—dirt enters and is moistened (aided by upper lip)
Food passes to pharynx—then to esophagus (tube like structure)—to crop
Crop (temporary storage area)…then to gizzard…(mechanical digestion)..then to intestine
Intestine—location of digestive enzymes to break down food—nutrients absorbed into blood steam here—nutrients carried throughout body by blood
Indigestible parts—pass through anus—waste materials sometimes called castings

44. The Earthworm and Other Segmented Worms
The Earthworm’s Circulatory System Continuous network of blood vessels Closed circulatory system—blood never leaves the blood vessel Dorsal blood vessel—along back of earthworm; acts as a heart Five aortic arches Ventral blood vessel—along the bottom of the worm

45. The Earthworm and Other Segmented Worms
The Earthworm’s Circulatory System Blood passes from arteries to smaller capillaries to the veins Veins take blood back towards the heart

46. The Earthworm and Other Segmented Worms
The Earthworm’s Respiratory and Excretory System Exchanges carbon dioxide and oxygen through skin In emergency can go several hours without oxygen In storms come to surface because borrows fill with water Nephridia—tiny looped tubes that collect wastes from worm’s blood