1. Animals, Part I Invertebrates
Introduction to Animals (Chapter 34)
Sponges and Jellyfish (Chapter 35)
Simple Worms (Chapter 36)
Mollusks and Annelids (Chapter 37)
Arthropods (except Insects) (Chapter 38)
Insects (Chapter 39)
Echinoderms (Chapter 40)

2. Animal Features Animals are: Eukaryotic Multicellular Heterotrophic
Their cells have proper nuclei, but no cell walls
Multicellular
Most animals have differentiated, specialized tissues.
Heterotrophic
They must get nutrition from other organisms
Most are herbivores (eat plants) or carnivores (eat meat)
But a few are parasites (consume living hosts) or symbiotic (live in mutually beneficial relationship)
In addition, most animals are mobile (they can move around, at least during some part of their life) and very responsive (most have a nervous system). Animals range in size from tiny (about a millimetre) to huge (a blue whale is over 30m long)

3. Kingdom Animalia
Part 1. The invertebrate animals

4. The Lower Invertebrates
Phylum Porifera, the Sponges
Phylum Cnidaria, the Jellyfish and corals
Phylum Ctenophora, the comb jellies
Phylum Platyhelminthes, the flat-worms
Phylum Rotifera, the rotifers
Phylum Nematoda, the round-worms

5. Evolution of Invertebrates
Protists
Echinoderms
Sponges
Jellyfish
Annelids and Arthropods
543
510
439
409
363
290
245
206
144 65 2
Paleozoic
Mesozoic
Cenozoic
Ordovician
Jurassic
Devonian
Carboniferous
Cambrian
Silurian
Permian
Triassic
Cretaceous
Ternary
Quaternary

6. Sponges Sponges look plant-like, but they are in fact animals.
Adult sponges are sessile, that is, they attach to rocks and don’t move around.

7. Sponges feed by filtering food out of the sea water.

8. Jellyfish and Relatives
Phylum Cnidaria
Phylum Ctenophora

9. Jellyfish, Hydra and Coral (Phylum Cnidaria)
Cnidaria can have two basic body shapes, the “polyp shape” and the “medusa shape”
The two shapes are similar, with tentacles, a mouth opening, an epidermis and a jelly-like mesoglea.
In the “polyp” shape, the tentacles open upwards,
In the “medusa” shape the tentacles hang downwards.

10. Jellyfish are medusa, hydra, coral & sea anemone are polyp

11. Nematocysts (ouch!)
Jellyfish have stinging cells called nematocysts on their tentacles. These can kill or paralyze small prey, allowing the slow-moving jellyfish to consume them.
The Portuguese-man-of-war is a colonial relative of the jellyfish. It can be quite deadly

12. Comb Jellies (Phylum Ctenophora)
A more distant relative of the jellyfish is the elusive comb jelly.
Comb jellies lack stinging cells.
Some display bioluminescence – the ability to glow in the dark

13. Flatworms, Rotifers and Roundworms
Phylum Platyhelminthes
Phylum Rotifera
Phylum Nematoda

14. Platyhelminthes The Flat Worms
Flatworms include harmless free-living organisms like the planarian
There are also parasitic flatworms, like tapeworms (cestodes) and flukes (trematodes)

15. Rotifers
Rotifers are microscopic and near-microscopic animals. They may be spherical or worm-like

16. Nematodes The “Roundworms”
Nematodes are cylindrical worms, usually pointed at each end.
They range in size from microscopic to about a meter long.
They include both free-living and parasitic varieties, with the parasitic ones being larger.

17. A microscopic roundworm
Warning: close your eyes if you are squeamish!
Child infested with ascaris roundworms. It is unusual to see them on the mouth & nose. Usually they come out the other end!
Ascaris, a parasitic intestinal roundworm

18. Roundworms & Disease Nematodes cause several diseases
Trichina worm in Muscle
Nematodes cause several diseases
Trichinosis: a disease of the muscles and nerves caused by microscopic worms from uncooked meat (especially pork)
Hookworms: intestinal parasite (cause bleeding)
Pinworms: intestinal parasite (cause itching)
Skin conditions: (worms enter cracks in feet)
Heartworms: (common in dogs, can kill)
Pinworms are very common. It is estimated that between 30 and 80 percent of children in North America have been infected by pinworms at some point.

19. The Higher Invertebrate Phyla
Phylum Mollusca, the mollusks
Clams, oysters, snails, slugs, octopus, squid
Phylum Annelida, the segmented worms
Earthworms, seaworms, leeches
Phylum Arthropoda “arthropods” The joint-legged invertebrates.
Crustaceans, insects, arachnids
Phylum Echinodermata, the echinoderms
Starfish, sand-dollars, sea urchins, sea cucumbers

20. Mollusks
Phylum Molluska

21. Mollusks There are three main types of mollusk
Bivalves (clams, oysters, scallops etc) have two shells surrounding the soft mollusk inside
Gastropods (snails, sea-snails, slugs) often have a spiral shell and crawl on a belly-foot
Cephalopods (octopus, squid, cuttlefish, nautilus) have multiple tentacles attached to their “head”. Cuttlefish have an internal shell or “bone” and nautilus have a spiral, chambered shell.
Bivalve means “two shells”
Gastropod means “belly-foot”
Cephalopod means head-foot

22. Mollusks- Class 1: Bivalves
Most bivalves are filter-feeders

23. Mollusks, Class 2: Gastropods
Gastropods crawl on their bellies. They scrape up food with a tongue-like organ called a radula.
Most gastropods have two small eyes at the end of tentacle-like stalks above their “heads”
Slugs lack shells, but most gastropods have spiral shells with torsion. Sea snails include many species, such as whelks and conchs.
snail
Eyes
Radula
slug
Sea snail

24. Mollusks, class 3: Cephalopods
Cephalopods include octopus, squid, cuttlefish and nautilus
Most cephalopods are carnivorous predators with tentacles or “arms”
octopus
squid
cuttlefish
nautilus

25. Cephalopods in Action

26. Parts of a Squid

27. Differences in cephalopods
Cephalopod type
Shell type if present
Tentacles*
(arms + tentacles)
Tentacle features
Fun Facts
Squid
None
10 (8+2)
Suckers and hooks
Colossal squid are the largest invertebrates
Octopus
8 (8+0)
Suckers
Secrete “ink” to escape predators
Cuttlefish
Internal “cuttlebone”
No suckers
The most intelligent invertebrates. Chameleons of the sea.
Nautilus
Spiral
chambered
Up to 90
(≈90 + 0)
Most of its shell is empty chambers used for buoyancy
* The term tentacle is used here for all tentacle-like limbs. In fact, the smaller limbs of the squid are properly called “arms”, and only the longer ones are “tentacles”.

28. The Colossal Squid Largest Invertebrate Ever?
For over 100 years, scientists had suspected that there were some really large squid lurking in the deep oceans.
Jules Verne wrote a fictional account of such a creature in his 1870 novel “20000 Leagues Under the Sea”
In 2003 a complete specimen of a young squid was found (shown on table above)
In one weighing over 1000 lb was captured near Antarctica (upper left)
Possible length of adult?

29. Convergent Evolution
Mollusks and vertebrates have evolved separately for nearly a billion years, so they have no close common ancestors. Nevertheless, some features of cephalopods are remarkably similar to features found in some vertebrates. This is a case of convergent or parallel evolution.
octopus eye
Cat’s eye
octopus beak
Parrot beak 

30. Convergent Evolution
cuttlefish camouflage
chameleon camouflage 

31. 1. Define a mollusk
2. List the three types of mollusk, and give an example of each.
3. What is the largest known mollusk?
4. What is convergent evolution?
5. Give three examples of convergent evolution features that appear in mollusks, and state what other organism they are convergent to.

32. Annelids
Phylum Annelida

33. Annelids: the Segmented Worms
Examples
Earthworms
Sandworms
Leeches

34. Geological Timescale (Arthropods)
Crustaceans (Shrimp, Lobsters, Crabs etc.)
 Extinct
Trilobites
 Extinct
Sea Scorpions
Annelid
Ancestor
(Worm)
Horseshoe Crabs
Chelicerates
Arachnids (spiders, scorpions, mites, ticks)
Sea spiders
Myriapods (Millipedes & Centipedes)
Uniramia
Insects
543
510
439
409
363
290
245
206
144 65 2
Paleozoic
Mesozoic
Cenozoic
Ordovician
Jurassic
Devonian
Carboniferous
Cambrian
Permian
Triassic
Silurian
Cretaceous
Ternary
Quaternary

35. Giant Earthworm The Largest Annelid

36. That’s why some people (inaccurately)
say that worms have
Five hearts
Facts about annelids
Annelids are called “segmented worms” because their bodies appear to be made of about a hundred similar segments stuck tightly together.
Most annelids are hermaphrodites, they have both male and female sex organs, but they must still mate with different worms.
Earthworms have no real heart, but they have five pairs of “aortic arches” that pump blood
Annelids have “setae” that extend from their body like tiny legs. Earthworms’ are hair-like and retractable, but sandworms have paddle-like setae.

38. Arthropods
Phylum Arthropoda

39. Arthropods Joint-legged invertebrates See phylogenetic tree (p. 745)
Trilobites (extinct)
Crustaceans
Insects
Arachnids)
Centipdes & Millipedes
See phylogenetic tree (p. 745)

40. Arthropod Features All arthropods have…
An exoskeleton (external skeleton containing a tough carbohydrate compound called chitin)
Jointed appendages (legs and/or claws)
Segmented body design
Ventral nerve cord (their main nerve goes down their belly side instead of their back side)
Segmented body
Tough exoskeleton
ventral nerve
Jointed legs

41. Most (but not all) arthropods also have these features…
Compound eyes
Eyes containing hundreds of individual lenses
Moulting
As the arthropod grows is must shed its old exoskeleton several times.

42. Arthropods, Subphylum 1: Trilobites
Trilobites were ocean-dwelling arthropods of the Palaeozoic era.
Trilobites are all extinct. They are found only as fossils
Artist’s conception of trilobite
Trilobite fossil

43. Arthropods Subphylum 2: Crustaceans
Most crustaceans are aquatic:
crabs*, lobsters, crayfish, barnacles and shrimp.
Two types of crustaceans are terrestrial, and are often mistaken for insects.
Sow-bug, pill-bug
Sow bug pill bug
*except the horseshoe crab, which is more closely related to the arachnids

44. Body Parts in a Crustacean
The body is divided into two main regions
The cephalothorax ( a fused head & thorax protected by a tough “shell” or carapace)
The abdomen (segmented tail area)
Most crustaceans are decapods (meaning 10 legs). They have four pairs of walking legs and one pair of claws (chelipeds).
In addition to their main legs, they have several other appendages
Antennae and antennules
Swimmerets
Maxilla and maxillipeds
A telson (tail-piece) and uropods (tail)

45. Internal Anatomy of a Crustacean
The heart of a crustacean is on its dorsal (back) side, and its largest blood vessel runs along its back.
It has a complete digestive system, with a two-part stomach, a digestive gland and an intestine.
Its largest nerve runs along its ventral (belly) side, from the brain to the tail, with several nerve bundles or ganglia along it.
Respiration is through gills under the carapace.

46. Arthropods Subphylum 3: Chelicerates
Chelicerates include:
Sea scorpions (extinct but huge)
Horseshoe crabs
Sea spiders
Arachnids
(arachnids are the only
group we will examine in
detail.)

47. Arachnids Phylum Arthropoda, Subphylum Chelicerata, Class Arachnida
Arachnids include spiders, scorpions, ticks and mites.
Most arachnids have four pairs of walking legs (“eight-legged freaks”), but may also have additional appendages…
Scorpions have a pair of chelicerae (claws)
Spiders & scorpions have pedipalps near their mouth.

48. Arachnid Facts
Eriophyid mites are among the smallest of all arthropods, measuring only 125 to 250 μm in length
The world’s largest spider is the Goliath “bird-eater” tarantula… over 30 cm (one foot!) long with 5 cm fangs.
The most venomous spider in the world is the Brazilian wandering spider

49. Arthropods, Subphylum 4: Uniramia*
Uniramia include:
Myriapods (centipedes and millipedes)
Insects (over species of them!)
*in older classification systems, Mandibulata is sometimes used instead of Uniramia

50. Myriapods: centipedes & millipedes
Ok, they don’t really have exactly 100 or exactly 1000 legs.
‘nuff said.

51. Insects, the hexapods Phylum Arthropoda, Subphylum Uniramia
Insects, the hexapods Phylum Arthropoda, Subphylum Uniramia*, Class Insecta
Insects are the most widespread of all invertebrates.
Insects exist in nearly every climate, and there are over species
(that’s ¾ of a million different types of insect!)

52. Insect Features Insects have the features of arthropods, plus
Three pairs of walking legs (6 legs total)
Three distinct body divisions
Head (front end of body)
Thorax (“chest”or central region of body)
Abdomen (back end of body)
(In a few insects, eg. Grasshopper, the head and thorax are partially fused into a “cephalothorax”)
Some insects also feature:
Metamorphosis (complete or incomplete)
One or two pairs of wings in the adult stage.

53. Metamorphosis
Metamorphosis is a major change in body form as an organism matures
Metamorphosis is found in several types of animal, but most notably in:
Insects
Amphibians
The younger life stage is usually called the larva, the older life stage is the adult.
Some forms of metamorphosis have additional stages, such as nymph or pupa.

55. Types of Metamorphosis
Incomplete metamorphosis:
The body change is usually minor, such as the growing of wings or a slight change in body shape. Eg. Grasshopper
When metamorphosis is incomplete, the term nymph is often used instead of larva.
Complete metamorphosis:
The body change is major, and the adult appears completely different from the young organism.

56. Incomplete metamorphosis of Grasshopper

57. Complete Metamorphosis
3rd Instar
Larva
Pupa
2nd Instar
Larva
1st Instar
Larva
Adult
Egg

58. A Few of the Many Orders of Insect
Coleoptera: beetles, ladybugs
Diptera: flies, mosquitoes
Orthoptera: Grasshoppers, crickets
Lepidoptera: butterflies, moths
Hymenoptera: bees, wasps, ants

59. “Float like a Lepidoptera
Sting like a Hymenoptera”

60. Insect Systems Respiratory system Digestive system: Excretory system:
Insects have no lungs. They have holes called spiracles on the sides of their abdomen. The spiracles lead air into a system of tubes called tracheae. Their blood does not carry oxygen (no hemoglobin)
Digestive system:
Contains crop and gizzard (foregut); the stomach with several caeca or storage sacs (midgut); and the intestine with rectum and anus (hindgut)
Excretory system:
Insects do not have kidneys as such. Instead they have a cluster of tubes called Malpighian tubules that gather liquid wastes into the intestine.

61. spiracle

62. The myth of giant insects…
If an ant were the size of a human, it could lift 2000 pounds over its head
Giant radioactive insects terrorize Nevada towns.
Cockroaches could survive nuclear wars
If an ant were the
size of a human
It couldn’t even lift
its own body weight
due to the “square-cube”
law. Strength increases
as the square of size,
but weight increases
as the cube of size
MYTH
Busted
MOVIE MYTH
Busted
Plausible

63. The Truth
Insects and other arthropods have very heavy exoskeletons. Increasing the size of an insect would increase its exoskeleton to the point where it would be difficult to lift.
Insects also have a primitive respiratory system. Without proper lungs large insects have a difficult time getting oxygen.
Fact: Much larger (but not truly gigantic) insects existed in the paleozoic era (200 million years ago) when there was more oxygen in the atmosphere.

64. Titaneus giganteus Palaeozoic Dragonfly
Today’s largest insect million years ago
(a model, not the real thing)

65. Starfish and their relatives
Echinoderms
Starfish and their relatives

66. Phylum Echinodermata The Echinoderms
Echinoderms include:
Starfish
Sea Urchins
Sand dollars
Sea cucumbers
Sea lilies

67. Echinoderm Features All Echinoderms are aquatic
Echinoderms are deuterostomes
This means their digestive system develops from both ends, no just from the mouth end.
It also means that they are more closely related to vertebrates than their appearance would suggest.
Echinoderms have radial symmetry.
Rather than more common bilateral symmetry.
Most have five lines of symmetry (pentaradial) but a rare few have up to two dozen*.
*see page 784 bottom right

68. Five lines of symmetry

69. Echinoderm Movement
Echinoderms have a “water vascular” system that pumps water through “canals” in their bodies
The water vascular system also operates many tiny “tube-feet” underneath the body to allow the echinoderm to crawl along the bottom.

70. Structure of a Starfish
Digestive system in pale green
Water vascular system in pale orange
Reproductive system in purple

71. Phylum Cordata The vertebrates and their relatives
Chordates
Phylum Cordata
The vertebrates and their relatives

72. Non-vertebrate Chordates
Phylum Chordata includes all organisms with a dorsal nerve chord and with a “notochord” at some stage of life.
A notochord is a tough, flexible rod that protects the nerve.
Most chordates are vertebrates, that is they develop a backbone around their notochord, but…
Lancelets (eg. Amphioxus) keep their notochord for life and never develop a true backbone.
Tunicates (Sea squirts) lose their notochord and never develop a backbone
Dorsal means
running along the
backside, as opposed
to the belly side

73. Amphioxus sp. (a lancelet)
Diagram of a lancelet
Photograph of a lancelet

74. Tunicates (sea squirts)
A whole colony of sea squirts
Sea squirt diagram

75. End of the Invertebrates Now its time to develop some Backbone, like the rest of the chordates