2. Invertebrates I: Sponges, Jellyfish, and Worms

3. 15A What is an Invertebrate?
Prefix –in means “not” or “without”
Vertebra is one of the bones along the back of an animal
An INVERTEBRATE is an animal without a backbone
Most animal species are invertebrates
Skeleton – a structure in animals and humans that provides mechanical support for muscle attachment and maintaining body shape

4. 15A What is an Invertebrate?
Although an invertebrate does not have a backbone, it does have a skeleton
It may have either an internal or external skeleton made of minerals similar to limestone, glass, protein, and even ordinary water

5. 15A Review 1. About how many animal species are there?
2. Why is a bee considered an invertebrate?
3. Besides bone, list three substances that could compose an animal's skeleton.

6. 15B Sponges Sponges are “pore animals”
Their existence depends on the number of pores in their bodies through which they pump water that brings food and oxygen in and carries wastes out
Phylum Porifera
All sponges live in the water, and most live in oceans
Adult sponges remain permanently attached to solid objects and are unable to move place to place, BUT embryonic sponges can swim around briefly

7. 15B Sponges Have skeletons made of spongin, of spicules, or of both
Spongin - is a flexible, fibrous protein
Spicules – stiff, pointed little spikes made of calcium carbonate or silica
Be familiar with Figure 15B-1 on page 269
Collar cells – cells lining the central cavity, which possess flagella
Sponges are often called filter feeders because they filter water to obtain food

8. 15B Review
1. To what sponge characteristic does the name Porifera refer?
2. If adult sponges are permanently attached to solid objects, how can they colonize other areas?
3. What and how do sponges eat?

9. 15C The Jellyfish: A Cnidarian
Jellyfish belong to the phylum Cnidaria
They have tentacles with stinging cells
They are usually found in oceans; though a few can be found in freshwater
15C.1 The Body of a Jellyfish
The Jellyfish has a hydrostatic skeleton.
Has a large central cavity surrounded by two tissue layers.
Layers are called the ectoderm and the endoderm.
Inside the endoderm is the gastrovascular cavity were the Jellyfish digests its food.
The Jellyfish has no brain, just a network of nerves.

10. 15C The Jellyfish: A Cnidarian
15C.2 Jellyfish Activities
The Jellyfish can defend itself and paralyze its prey with nematocysts (special cells found in the ectoderm).
The Jellyfish uses weak fiber muscle fibers in its tentacles to push the prey into its gastrovascular cavity.
Digestive enzymes are released by cells in the endoderm to break down the food in the gastrovascular cavity.
Jellyfish do not use their tentacles to swim. Most of the time jellyfish just float.
When they do swim, a set of muscle fibers around the rim of the jellyfish contracts.

11. 15C The Jellyfish: A Cnidarian
15C.3 Other Interesting Cnidarians
Hydras, corals, and sea anemones are also cnidarians.
The Portuguese man-of-war is a dangerous cnidarian that is actually a floating colony containing many specialized polyps.
The bodies of cnidarians have radial symmetry.
Radial symmetry means that they can be divided into equal halves by any plane along the length of the organism.
Cnidarians may be either free-floating or permanently attached to a solid object.

12. 15C Review
1. What is the supporting material in a jellyfish's skeleton? 2. Where do jellyfish digest their prey? 3. What is the soft body of a coral animal called?

13. 15D The Planarian: A Flatworm
Flatworm members = flat!
Bilateral symmetry (can be divided into two equal halves – like a mirror image)
Phylum Platyhelminthes
It is a free-living (not a parasite) flatworm that can be found in freshwater streams and in soil.
Flatworms can be found in the oceans, in fresh water inside other animals as parasites, or in the soil.

14. 15D The Planarian: A Flatworm
15D.1 The Planarian’s Nervous System
Neurons are long, thin nerve cells found throughout the body of an animal or human.
Most animals control their bodies through neurons.
A collection of neurons wrapped in protective coverings is called a nerve.
Many invertebrates have nervous systems that are fairly complex and require some coordination.
An invertebrate’s “coordination center” is a ganglion, sometimes called a simple brain.

15. 15D The Planarian: A Flatworm
15D.1 The Planarian’s Nervous System
The planarian has a simple nervous system. A longitudinal nerve runs down each side of its body.
A series of transverse nerves connects the longitudinal nerves.
The planarian’s ganglia coordinate its responses to stimuli.
A stimulus is something an organism can sense.
Planarians respond differently to different things such as touch, the flow of water, chemicals in water, and light.

16. 15D The Planarian: A Flatworm
15D.2 The Planarian’s Digestive and Excretory Systems.
The planarian’s body covering is a tissue that is one cell- layer thick.
Cilia on the underside of the planarian help it glide over underwater surfaces.
The mouth of he planarian is on its underside, near the middle of its body.
Just inside the mouth is a long branching cavity called the intestine which is lined with a layer of cells which is called the gastroderm.
The planarian eats by extending a muscular tube called the pharanx through the mouth and sucking food into the intestine.

17. 15D The Planarian: A Flatworm
15D.2 The Planarian’s Digestive and Excretory Systems.
The planarian’s food is digested in the gastroderm.
Nondigestible material is pushed out of the intestine though the mouth.
The planarian’s intestines extend to every area of the worm’s body and food is moved throughout the intestine by the twisting movements of the planarian and by flagella.
The planarian has a mass of cells between its body covering and gastroderm. Some of the cells are specialized for particular functions.
The planarian’s body is very thin. This allows the animal’s cells to exchange oxygen and carbon dioxide directly with the environment.

18. 15D The Planarian: A Flatworm
15D.2 The Planarian’s Digestive and Excretory Systems.
The planarian gets rid of its waste products through a system of tiny tubes.
At the end of these tubes are structures called flame cells. The cilia at the end of these structures look like tiny flames.
These cilia move water and wastes through the tubes to tiny holes called excretory pores. Here the water and wastes are excreted from the planarian.

19. 15D The Planarian: A Flatworm
15D.3 Other Interesting Flatworms
Some other common flatworms include tapeworms, flukes and marine flateworms.
Tapeworms (a common parasite of animals and humans) are found in the digestive tracts of various animals.
A Tapeworm has a head equipped with hooks and/or suckers to attach it securely to the digestive tract. It is nourished by absorbing dissolved food that is passing through this digestive cavity.

20. 15D Review
1. What type of symmetry does a planarian have? 2. How many longitudinal nerves does a planarian have? 3. Where is the mouth of a planarian?

21. 15E Roundworms 15E.1 Ascaris – A Common Roundworm
In the phylum Nematoda
Have round, tubular bodies and are tapered at each end
Some are serious parasites of humans, animals, and plants; others are free-living
Many are microscopic; some may grow to be 30cm (12in) long!
The adult Ascaris can be found in the intestines of various animals

22. 15E Roundworms 15E.1 Ascaris – A Common Roundworm
The tiny eggs are swallowed and young larvae burrow in the intestine walls and enter the blood stream
They eventually reach the lungs and travel up the throat and are reswallowed
In the intestine again, larvae develop into adults
Humans, cats, dogs, and various farm animals can have round worms

23. 15E Roundworms 15E.2 Other Interesting Roundworms
Other serious roundworm parasites include hookworms, pinworms, and trichina worms
Trichina often form cysts containing larvae in the muscle tissue of pigs
Vinegar eel – appear as tiny threads in unpasteurized vinegar and cider products (not parasitic thankfully!)
Other roundworms cause serious plant diseases

24. 15E Review
1. Name the phylum that includes roundworms 2. Where does an adult Ascaris normally live? 3. Are roundworms parasites of animals only? Explain.

25. 15F Segmented Worms 15F Segmented Worms
The earthworm has a long, slender body made of a series of similar segments
The segmented body plan is what distinguishes earthworms from others
Phylum Annelida
Leeches, tube worms, scale worms, sandworms, and fireworms also belong to this group

26. 15F Segmented Worms 15F.1 The Body of an Earthworm
Covering the earthworm’s body is a thin, skin called an epidermis
The epidermis exchanges gases (carbon dioxide and oxygen) with the environment.
It also secretes a thin outer coating called the cuticle
The cuticle protects the earthworm from harmful parasites and substances
Cuticle must be thin and its epidermis kept moist for gas exchange

27. 15F Segmented Worms 15F.1 The Body of an Earthworm
Under the epidermis, are two muscle layers
They provide support and help it move
One layer is arranged in circles around the earthworm’s body
When these muscles contract, the worm becomes longer and thinner
The other muscle layer is arranged in long strips running from the head to the tail
When these muscles contract, the earthworm becomes shorter and wider

28. 15F Segmented Worms 15F.1 The Body of an Earthworm
The earthworm moves by using its muscles and tiny bristles on each segment
It moves forward by extending the bristles on its rear segments into the soil
Once the rear segments are anchored, it contracts its circular muscles – which causes it to become long and thin, pushing its front end forward
Then the worm releases the rear segments and extend the front half into the soil, pulling itself forward by contracting its long muscles

29. 15F Segmented Worms 15F.2 The Earthworm’s Nervous System
There are many sensory receptors on the body of the earthworm
Sensory receptor – a structure that can sense a stimulus and then start an impulse traveling along a neuron
Some of its sensory receptors are sensitive to chemicals in the soil, others to light, and some to temperature and other conditions
There are more sensory receptors at an earthworm’s front end because it leads with its front end
They help the worm to sense whether it is approaching food or danger so that it can react accordingly

30. 15F Segmented Worms 15F.2 The Earthworm’s Nervous System
The earthworm’s neurons carry impulses from the sensory receptors in the front of the worm to two large ganglia in the third segment
Sensory receptors in other areas send impulses to the nerve cord in the lower half of the worm
Nerve cord – a bundle of neurons that begins at the two large ganglia and continues to the tail of the worm
Along the nerve cord there is one small ganglion in each segment of the worm

31. 15F Segmented Worms 15F.2 The Earthworm’s Nervous System
The ganglia interpret the impulses from the sensory receptors, and the worm decides what to do with them
Interprets and decides describe the worm’s response to stimuli – but these words are not good words because they imply intelligence
Earthworms have very little intelligence
Neurons carry impulses to muscles, bristles, and other structures that will enable the earthworm to respond properly

32. 15F Segmented Worms 15F.3 The Earthworm’s Digestive System
often eats the soil as it forms tunnels
Most of the soil is indigestible, but within the soil are decaying leaves, fungi, and small creatures
Has a long, straight digestive tract
At various points along the tract, there are enlargements, constrictions, infoldings, and glands
Each has a separate function
The mouth secretes fluids that moisten the soil as it enters
Look closely: you may notice an upper lip! Used to force food in their mouth

33. 15F Segmented Worms 15F.3 The Earthworm’s Digestive System
From the mouth, the soil passes to the pharynx
Then to the esophagus – a tubular passageway that carries food from the pharynx to the crop
Crop – looks like a swelling in the digestive tract
Food leaving the crop passes into the gizzard – another bulge in the digestive tract
Then it goes from the gizzard to the intestine
Indigestible parts pass through the intestine and leave the digestive tract through the anus
Castings – wastes that accumulate in piles outside the tunnels

34. 15F Segmented Worms 15F.4 The Earthworm’s Circulatory System
A continuous network of blood vessels
Closed Circulatory System – when blood never leaves the blood vessels
Dorsal blood vessel – along the back – acts as a heart
It pumps blood forward to the five sets of aortic arches
Ventral blood vessel carries blood throughout worm
Capillaries – blood passes through arteries and enter tiny blood vessels called capillaries
Blood flows from arteries through capillaries to veins
In closed systems, blood is carried toward the heart

35. 15F Segmented Worms Path of blood flow in a closed circulatory system:
15F.4 The Earthworm’s Circulatory System
Path of blood flow in a closed circulatory system:
Veins heart  arteries  capillaries  Veins

36. 15F Segmented Worms
15F.5 The Earthworm’s Respiratory and Excretory System
Does not have special respiratory structures
Gas exchange through the moist skin
Excretory tubules – where wastes collect an are passed out of the body through tiny pores

37. 15F Review
1. Name three members of phylum Annelida besides earthworms 2. In which part of the earthworm's digestive system does mechanical digestion occur 3. How does an earthworm breathe? 4. How can our study of earthworms help us exercise dominion over the earth?

38. Invertebrates II: Mollusks, Arthropods, and Echinoderms

39. 16A Mollusks Mollusks include the following animals: Clams Snails
Slugs
Octopuses
Phylum Mollusca
Phylum with the 2nd highest number of species and is very important to the environment
Also important to man
Food (clams, oysters, and scallops)
Make things (pearls, mother-of-pearl buttons)
Pests or parasites (slugs and snails can be pests)

40. A Mollusk without a shell
16A.1 The Octopus
A Mollusk without a shell
It’s body lacks structure to give it firm support
It does have many muscles
Eight arms (tentacles) that has muscle to help it move its arms in any direction
On the underside of each arm, there are suction disks, which allow it to grasp items.
Food captured in its arms can be moved to its mouth (located under the head)

41. 16A.1 The Octopus
The suction disks can also be used to fasten itself to things
If an arm is destroyed or severed, it has the ability to regenerate (grow) a replacement!
Although it hunts live food (crabs, lobsters, and shelled mollusks), it appears to be a timid animal
If it senses danger, it hides
It moves by gliding along in the water – but it is a slow creature
In order to move quickly, it forces water through a muscular tube called a siphon
This jets the octopus through the water
Occasionally, when frightened, it will release an inky black fluid into the water to serve as a “smoke screen”, allowing it to get away.

42. 16A.1 The Octopus
The octopus has a thin, flexible skin that helps its body hide more easily in the cracks between rocks and the ocean floor
It can “pour itself” into gaps and completely change its body shape
It can also cause different colored cells on their skin to spread out their pigments, helping to change colors!
It can become visible against almost any background
Its colors may also reflect its level of stimulation
If it is startled, it usually turns pale; when it is excited, it often turns red

43. 16A.2 The Clam A Mollusk with a shell
It produces a shell to protect and cover their bodies
Clams, mussels, and scallops produce two shells hinged together – called bivalves
Snails and conchs produce a single shell - called univalves

44. 16A.2 The Clam
The clam’s soft body is covered with a thin skin called a mantle
Outside of this skin is where material is produced that hardens to become a shell
As it grows, it adds layers to the shell
The newest part of the shell is thinnest
It also has powerful muscles that keep its shell tightly closed
When a clam moves, it sends out a muscular FOOT
It is hatchet shaped and is pushed into the sand and expanded
The muscles contract to shorten the foot and pull the animal and shell forward

45. 16A.2 The Clam They do not hunt for their food
Clams are filter feeders
They dig into the sand and send two tubes called siphons out to the water.
The siphon is used to draw water into the shell, where tiny food particles are filtered out
The other siphon sends the water away from the clam to remove wastes

46. 16A Review 1. Name a Mollusk that is edible
2. What does an octopus use its siphon to do?
3. What part of the clam's body manufactures its hard shell?

47. 16B Arthropods

48. 16B Arthropods Phylum Arthropoda They serve as:
The most species of any animal phylum
The insect class is the largest class within this phylum
Almost a million species of insects identified
Many play significant role in our world, especially insects
They serve as:
Pollinators, decomposers, crop eaters, disease carriers, and parasites
Animals in this phylum have:
Exoskeletons, and jointed appendages such as legs and antennae
Exoskeleton – hard, nonliving, outer covering that supports and protects the animal

49. 16B.1 A Typical Insect’s Body
Insects typically have three sections to their bodies:
Head
Thorax (middle part)
Abdomen
They also have three pairs of legs (6 total)
Caterpillars appear to have more than three pairs, but actually they are not real legs
Most insects have two pairs of wings, although some may have none or one pair
Compound eyes: their eyes have thousands of small sections
Grasshoppers see in a mosaic of smaller images
See page 286 for picture

50. 16B.2 Body Systems in the grasshopper
Grasshoppers have blood and a circulatory system (like all arthropods)
Blood – is a fluid tissue made up of cells floating in liquid
The main function of blood – to carry substances to and from all parts of the body
Heart – muscular organ that pumps blood to all body cells
Has a series of small tubular hearts located just under its exoskeleton (see explanation p. 289)
Artery – blood vessels that carry blood AWAY from the heart
Open Circulatory System – Blood that does not remain in the blood vessels

51. 16B.2 Body Systems in the grasshopper
The blood is colorless, not red
It carries mostly food and wastes and has little to do with oxygen transport
Tracheae – where insects receive oxygen and release carbon dioxide
They are tiny elastic tubes that branch throughout the insect
Air is pumped in and out of these twenty small openings called spiracles
Insecticides – chemicals only harmful to insects and not other living things
As blood circulates, it collects wastes
These wastes are filtered out of the blood and collected by thread-like excretory tubules

52. 16B.3 Insect Life Cycles
Insects go through one of two different life cycles:
Some molt throughout their life
Molting – occurs when insects shed their old exoskeletons and replace them with new ones
This life cycle is called incomplete metamorphosis
Metamorphosis – for insects mean, a change in body form
Incomplete Metamorphism:
Start as eggs
Go through a series of molts
Developing stages called nymphs
Then reach adulthood
Example: grasshopper

53. 16B.3 Insect Life Cycles Complete Metamorphosis Involves 4 stages Egg
Larva
Most active stage
Larvae of moths and butterflies known as caterpillars
Known for destructive appetites
Other larvae – maggots (flies) and grubs (beetles)
Pupa
Resting stage where larvae uses food to change body shape
Cocoon (moth), chrysalis (butterfly), puparium (flies)

54. 16B.3 Insect Life Cycles
Each time one that undergoes COMPLETE metamorphosis and molts, it passes into another stage
Most butterflies die soon after it has mated
Butterflies do not become bigger butterflies

55. 16B.4 Other interesting Arthropods
Not all arthropods are insects
Some are barnacles, crabs, lobsters, shrimp, pill bugs, centipedes, scorpions, and tarantulas
These differ from insects by the number of body segments and appendages
Centipedes and millipedes are not worms
Centipedes
Flattened
One pair of legs per segment
Poisonous claws to kill prey
Millipedes
Somewhat rounded body
Can have up to 100 body segments, and most segments will have 2 pairs of legs
They are not hunters like centipedes

56. 16B Review 1. What are the three main parts of an insect's body?
2. What type of eyes do insects have?
3. What can we learn from an ant's behavior?
4. List the four stages of metamorphosis
5. List the three arthropods other than insects
6. What sex are worker bees?

57. 16C Echinoderms

58. 16C Echinoderms
Starfish – aka sea stars – are ocean dwelling animals that, along with sea urchins, sand dollars, sea cucumbers, and similar organisms are called echinoderms
Starfish are supported by a system of hard, flat plates just under the skin
Hard plates and spines provide protection
Radial symmetry
Arms are called rays
They can regenerate or grow new rays if needed

59. 16C Echinoderms How do starfish move?
Have a water-vascular system that is key to movement
Noticeable part of system – rows of tiny tube feet on the bottom of each ray
Tube feet function like tiny suction cups
They stretch out, attach, and then pull itself forward on hard surfaces
Favorite food of starfish – clams
Climbs on top of a clam and uses tube feet to pull open shell (could take hours)
Then, turns its stomach inside out and pushed it throuh the opening of the clam shell
Digestive juices digest the soft part of the clam

60. 16C Review
1. What is the function of the hard plates and spines in a starfish?
2. Where are a starfish's tube feet located?
3. What does a starfish not need teeth?