1. Animal Form and
Function
Chapter 33 Invertebrates
Part 1
Aim: What are characteristics of
invertebrates?
Do Now: What characteristics are unique to
animals?
2. You Must Know…
• The traits from Figure 7.11 which are used
to divide the animals into groups
• Examples of unique traits for each phylum
discussed
• The evolution of systems for gas
exchange, respiration, excretion,
circulation and nervous control
3. 32.1 Kingdom Animalia
Animals have the following characteristics:
1. They are multicellular heterotrophs
2. Most have muscles and nervous tissue
3. Most reproduce sexually, with a flagellated
sperm and a large egg uniting to form a
DIPLOID zygote.
4. The diploid stage dominates its life cycle
5. Have Hox genes
4. • Homeotic genes are genes in animals
that determine which parts of the body
form what body parts.
– Hox genes, a family of genes that play
important roles in development
• segmentation
• Highly conserved
– Similar sequence in all animals
• Small differences in DNA sequences, lead to large
differences in body plan
5. Invertebrate Terms:
• Appendages: Any part of the animal coming from the main body or
trunk- arms, legs, antennae, etc.
• Asymmetry- no symmetrical
• Bilateral symmetry- mirror images when cut from head to anus
• Radial symmetry- mirror images when cut through the central axis
• Dorsoventrally- running from back to front
• Exoskeleton- an external skeleton, shell
• Endoskeleton- an internal skeleton
• Alimentary canal- tube running from mouth to anus, including all of the
organs the food passes through
• Digestive system- the alimentary canal plus accessory organs (liver,
pancreas)
6. Invertebrate Terms
• Segmented: the division of the body into similar parts
• Sessile- is not motile; anchored to a substrate
• Filter-feeder- collects particles as water flows through
them
• Gastrovascular cavity- sac-like digestive structure with
one opening that serves as the mouth and anus
• Gut openings: 0, 1 (same mouth/anus) or 2 (separate
mouth and anus)
• Cnidocytes/nematocyst- stinging structure
• Cephalization- sense organs at anterior (head) end
• Open circulatory system- blood is not contained entirely
in vessels
7. InvertebrateTerms
• Metazoa: multicellular
• Parazoa: lacking true tissues
• Eumetazoa: True tissue
• Radiata: Radial Symmetry
• Bilateria: Bilateral Symmetry
• Deuterostomes: deuterostome development
• Protostomes: protostome development:
• Acoelomate: no cavity
• Coelomate: True body cavity
• Pseudocoelomate: body cavity from mesoderm and
endoderm
8. Animal Form and
Function
Chapter 33 Invertebrates
Aim: What are characteristics of
invertebrates?
Do Now: What do you know about
invertebrates? Give several examples.
9. Invertebrate Phyla Characteristics
• Observe one representative organism
from each invertebrate phyla
• Write the characteristics that you observe
for each invertebrate phyla in the
phylogenetic tree
• Use the “invertebrate terms” notes in your
notebook for help with identifying
characteristics for each phyla
11. Invertebrates
• Animals that lack backbones
• Domain Eukarya
• Kingdom Animalia
• Invertebrates are classified under many phyla
– There is not “Invertebrate Phylum”
• Branch “metazoa”- multicellular
• Order of invertebrates is in order of evolution-
see a pattern of simple to complex in body plan
13. 1. Subkingdom Parazoa: Sponges
Subkingdom Parazoatrue tissues)
(lacking (sponges)
• aka Phylum Porifera
Characteristics of Sponges:
• Sessile (anchored to a substrate)
– But embryo is mobile
• Lack symmetry
• Lack true tissues- Simple!
– NO nerves or muscles (= no organs)
– No nervous, digestive, or circulatory
system
14. 1. Subkingdom Parazoa: Sponges
(lacking true tissues)
• Use water currents to obtain food, oxygen
and remove wastes (“filter feeders”)
– life processes are accomplished via CELLS (as
opposed to tissues or organ systems)
– Cells must be in contact with environment for
exchange of food, gas and wastes
• No gut opening
– *Intracellular digestion: cells engulf food
particles by phagocyotosis; vacuoles fuse with
lyosomes for digestion
• Body looks like a sac with pores (Porifera) in it
– their body contains only 2 layers of cells so they
can complete all life functions!!
19. 2. Subkingdom Eumetazoa (animals with true tissues)
• Subkingdom Eumetazoa (true tissue)
– All animals, except for sponges (Parazoa)
A. Phylum Cnidaria (hyrdrozoans, jellies, sea anemone, coral)
• Radial symmetry
• Few cell layers
– Have tissues, but no organs
• Central digestive compartment known as the gastrovascular
cavity
– One opening for mouth and anus
» Digestion, distribution of nutrients, elimination of
wastes
» Food gets digested in the cavity, then diffuses into
cells, wasted diffuses out of cells and leaves through
the cavity.
» Extracellular digestion- food breaks down in cavity,
not in cells
– Nerve net: Decentralized (little or no sense organs), no
brain, stimulus felt in entire organism
22. Chapter 33 continued
Aim: What are characteristics of
eumetazoa?
Do now: Describe distinguishing
characteristics of the following phyla:
Porifora and Cnidaria
24. 2. Subkingdom Eumetazoa
(animals with true tissues)
B. Bilaterally Symmetrical Animals
1. Phylum Platyhelminthes (flatworms)
• Examples: Planaria, tapeworms, flukes
• Flattened bodies with NO segmentation
• Cephalization
– Ganglia- clusters of nerves near anterior end (head) to detect
light
• Excretion (removal of waste) by flame bulbs (with
flagella) and protonephridia (neph= kidney)
• no specialized organs for circulation or gas exchange
– Simple diffusion because body is so flat
• Gastrovascular cavity with a single opening
• aquatic
26. Platyhelminthes: Tapeworm
• Internal parasites
• Live in the digestive tract
of vertebrates
• No digestive tract
– Absorb predigested food
around them
27. Checkpoint
1. Explain how tapeworms can survive
without a coelum, a mouth, a digestive
system or an excretory system.
29. 2. Subkingdom Eumetazoa (animals
with true tissues)
B. Bilaterally Symmetrical Animals
2. Phylum Nematoda (roundworms)
– Examples: pinworms, hookworms
– Cylindrical body with a tough cuticle
– Complete digestive tract (mouth and anus)
– No circulatory system
• Fluids circulate (diffusion)
– Bodies not segmented
– Decomposers in the soil
30. Animal Form and
Function
Chapter 33 Invertebrates
Part 1
Aim: What are characteristics of bilateria?
Do Now: Describe distinguishing characteristics
of the following phyla: Porifora, Cnidaria,
Platyhelminthes, and Nematoda
32. 2. Subkingdom Eumetazoa
(animals with true tissues)
B. Bilaterally Symmetrical Animals
3. Phylum Mollusca
– Soft-bodies animals
– Examples: slugs, bivalves (clams, etc), snails,
squid, and octopuses
– Characteristics:
1. Muscular foot for movement
2. Visceral mass containing most of the organs
3. Mantle- secretes a shell
33. 2. Subkingdom Eumetazoa
(animals with true tissues)
B. Bilaterally Symmetrical Animals
3. Phylum Mollusca
– *Open circulatory system
• The fluid (hemolymph) is not always contained
within vessels but sometimes circulates through
body sinuses called hemocoel (cavity)
– Complete digestive tract (mouth and anus)
– Excretion through nephridia (neph=kidney)
34. Mollusca: Classes
• Gastropoda:
– snails and slugs
• Bivalvia
– clams and oysters
– Shell in two parts
• Cephalopoda
– *Cephalization- brain
– Closed circulatory system- blood contained in vessels
– Squid- shell is reduced and internal
– Octopus and squid
35. Closed vs. Open Circulatory
System
• Closed: All blood is • Open: Some vessels;
contained within organs bathe in
vessels hemolymph (blood)
– Under pressure – Not under pressure
41. Animal Form and Function
Chapter 33 Invertebrates
Aim: What are characteristics of invertebrates?
Do Now: Describe distinguishing characteristics of the
following phyla: Porifora, Cnidaria, Platyhelminthes,
Nematoda, and Mollusca
43. 2. Subkingdom Eumetazoa (animals
with true tissues)
B. Bilaterally Symmetrical Animals
3. Phylum Annelida (segmented or ringed worms)
• Ex: earthworms, leeches
• Internal and external segmentation (with repeating
organs)
• Excretion by metanephridia in each segment
• Closed digestive system w/ specialized regions (crop,
gizzard, esophagus, intestine)
– 2 openings (mouth and anus)
• Brain-like central ganglia with ventral nerve cord
• hydrostatic skeleton (tube within a tube)
– No bones!
• Respire through skin by diffusion
• Decomposers (recycle nutrients)
48. 2. Subkingdom Eumetazoa (animals with
true tissues)
B. Bilaterally Symmetrical Animals
3. Phylum Arthropoda (jointed-legged animals)
– Ex: lobsters, shrimp, spiders, scorpions, insects,
milipedes and centipedes
– 1. Segmented with a hard 2. exoskeleton (chitin)
and 3. jointed appendages
– To grow, they molt or shed their exoskeleton and
secrete another one
– Well-developed nervous system (sense organs)
– open circulatory system-
– Various organs for gas exchange: gills, book
lungs, tracheal systems
49. Arthropod Adaptations for Land
• Exoskeleton:
– Protection
– Anchor for muscles
– Locomotion
– Protection from desiccation (drying out)
• Problem or any organisms living on land
• Developed sense organs
– Simple eye, smell, taste, touch
56. 2. Subkingdom Eumetazoa (animals with
true tissues)
B. Bilaterally Symmetrical Animals
4. Phylum Echinodermata (echinoderms)
– Spiny-skinned animals
– Examples: sea stars, sea urchins, sand dollars
– Larvae have bilateral symmetry; adults have radial symmetry
• Closest relative of vertebrate chordates
– Have thin skin covering an endoskeleton (calcium
carbonate)
– Complete digestive tract
– Water vascular system (network of internal canals that
branch into tube feet used for moving, feeding and gas
exchange)
– Reproduce sexually or asexually
58. Echinoderm Adaptations
• Spines
– Protection
• Skin gills
– Respiration
• Central nerve ring- nervous system
• Eyespot at the end of each arm
– Light sensitive
• NO respiratory system, excretory system
or circulatory system
– Water vascular system
59. 2. Subkingdom Eumetazoa (animals with
true tissues)
B. Bilaterally Symmetrical Animals
4. Phylum Chordata
– Includes two groups of chordates
1. Invertebrate chordates
– Lancelets and tunicates
1. Vertebrate chordates
– Characterized by vertebrae (backbone) that
encloses the spinal cord
– Sharks, fish, amphibians, reptiles birds and
mammals
60. Invertebrate Chordata
Lancelet Tunicate
• Few cm long and narrow • Sessile- live on ocean
• Water floor
• Retain chordate • Bilaterally symmetrical
characteristics as an larva
adult
65. March Through the Kingdoms
• Fill out the chart for the plant groups and
the invertebrate phyla
• Classify the list of organisms
• Graphic organizer- use your notes to write
distinguishing characteristics of each
phyla and class
• INVERTEBRATE Quiz TOMORROW
66. Invertebrate Dichotomous Key
• Observe characteristics of each organism
• Classify each invertebrate using the
dichotomous key
• Use the key terms on the back to help with
distinguishing the characteristics of each
organism
• Write the answers in your notebook
67. Invertebrate Activity
1. Classify the organisms
2. Use the concept map to check your
answers
3. Write characteristics (using the worksheet
and your notes) next to each organism
4. Fill in each branch of the phylogenetic tree
(on the back of the animal development
picture) with the correct characteristic
5. Create a dichotomous key for all of the
invertebrate pictures- use vocabulary from
the sheet provided
