Invertebrates
Chapter 29 and 30
Sponges, Cnidarians, Flatworms,
Roundworms, mollusks, annelids
Animal Kingdom Characteristics
- multicellular
- eukaryotic
- heterotrophs
- movement
- tissues
Body Plans
- Bilateral Symmetry- equal halves in one
direction
Radial Symmetry
•- 360 degrees; equal halves
- Asymmetry- cannot cut in equal halves
Body Development
- Ectoderm- outside body layer- skin and hair
- Endoderm- inside body layer- digestive tract
- Mesodermmiddle layer- muscles,
blood and organs
- Types of Body Cavities:
1. Coelom- true body cavity
- surrounded by mesoderm
-2. Pseudocoelom- false cavity
- between mesoderm and endoderm
3. Acoelomate
No body cavity.
Let’s Review.
What type of symmetry is this?
What type of symmetry?
Symmetry?
- Vertebrates- animals with backbones
- fish, amphibians, reptiles, birds, and
mammals
- Invertebrates- animals without backbones
- sponges, cnidarians, mollusks, worms,
echinoderms, arthropods
Sponges: Phylum Porifera
Asymmetrical – no
symmetry
No tissues or organs (cells
work together to perform a
specific function
2 body layers: endo-,
ectoSessile – do not move
Variety of shapes and
colors
Acoelemate – no body
cavity
Variety of Sponges
Digestion of sponges
Sponges are
consumers
Feed on bacteria,
algae, protozoans
(filter feeders)
Sponge digestion continued:
Reproduction
Either sexual or asexual
Asexual- fragmentation- each piece of
sponge will grow into a complete new
sponge
Sexual- hermaphrodite- produce both eggs
and sperm- release into water at different
times-sperm from one enters pores of other
to fertilize eggs- External fertilization
Reproduction continued
Produces a zygote- free swimming larvae
for a short time- attaches to surface- new
sponge
Cnidarians- the stingers
Coral
Characteristics of Cnidarians
Two Types:


Polyp – sessile, tube-like
with tentacles ex. Coarl, sea
anemone
Medusa – free swimming,
umbrella shaped

Jellyfish
Has tissues – ecto-, endoNematocysts – stinging
cells on tentacles
Radial symmetry
acoelamate
B
How Cnidarians Get O2?
Diffusion
Have nervous tissue.
Reproduction
Asexual- budding- small extensions of body
grow and then breaks away from parent
Sexual-some species are hermaphrodites

Others, female releases egg and male releases
sperm into water- External fertilization
hydra
Portugese Man of War (colony)
Jelly fish
Sea anemone
Sea Anemones
Coral reef
Coral reefs
Structure
See diagram – oldest
part is deeper. Newest
is toward the top.
Live symbiotically with
unicellular yellow
brown algaezooxanthellae
Benefit of Symbiotic Relationship:
Coral gets:
food
(coral can also capture food with tentacles)
Algae gets:
Protection and access to sunlight
Coral Bleaching
When coral ejects it’s algae- coral turns
white
Coral doesn’t get enough food- dies
Coral bleaching due to:
Diseases
Increased Ultra violet radiation
Sedimentation
Pollution
Increased water temperatures
Direct destruction by humans- anchors,
touching while diving
Bleached coral
Flatworms
Acoelomate
Bilateral symmetry
Platyhelminthes – flatworms
Characteristics of flatworms:
Can be parasitic, or free living
1 body opening
Hermaphrodites or asexual reproduction by
regeneration: breaking in 2, and each
becomes a new organism
Get O2 through skin- diffusion
Tapeworm
Body Two parts:


Scolex – head
Proglottids – body
sections
Attach to inside of
intestines
Parasite
Ex. Beef tapeworm:
become infected by
eating raw beef.
Getting Beef tapeworm:
Blood fluke - causes Schitomiasis
Planeria
Eyespots- light
Pharynx- extends like a straw, releases
enzymes- breaks down food , sucks it up
Sensory pits on side of head, detect food,
chemicals, and movement
Ability to regenerate
planeria
29-4 Roundworms
Pseudocoelum
Tube within a tube
body
2 body openings
Move in a side to side
manner
parasites
Ex. Ascaris - hookworm
Carried through
human waste to soil
If ingested eggs enter
large intestine –
becomes larvae
Larvae bore through
blood vessels
Back to the intestine to
mate
Ascaris in pig intestine
Trichinella – pork roundworm
Causes Trichinosis
Eating improperly
cooked pork
Lymphatic Filariasis
Mollusks and Annelids
Chapter 30
Mollusks
Characteristics




Invertebrates
Larval stage
Marine, freshwater,
terristrial
coelomates
Mollusks have 3 parts to body:
Visceral mass –
contains organs
Mantle – tissue
around visceral mass
(secretes a shell)
Foot - locomotion
Other Mollusk characteristics:
Exoskeleton

Sometimes called a
valve
Outer skeleton
•Radula
(not in bivalves)
Tongue-like structure
Organ systems of mollusks:
Excretory – get rid of
waste:
Open Circulatory
System –heart pumps
fluid through a series
of vessels out into
body cavity
Organ Systems of Mollusks
Reproduction – most
have separate sexes,
external fertilization
Respiration – use gills
30-2 Groups of Mollusks
Bivalves – “two
valves”
Valves held together
by strong muscles
No radula
Filter feeders
Examples: clams,
oysters, scallops
Bivalve Photos
Gastropods
Examples are snails and
slugs
Single shell or none
Use radula to scrape food
off of rocks etc
Land snails –
hermaphrodites, aquatic
snails – separate sexes
Herbivores
Gills or lungs?
Cephalopods – “head footed”
Examples: squid, octopus
Large head with tentacles
Eyes
Marine predators
(consumers)
Ink sac – for protection
Internal shell – pen
Brain present – complex
Skin can change color
gills
Phylum Annelida
Segmented worms
Examples: earthworms, leeches,
sandworms
Segmented body
Coelum
Bilateral symmetry
Abundant in all habitats
Organ Systems in Segmented Worms
Closed circulatory
system
Excretory system –
nephridia
Breath through skin
Bristles – setae
Reproduction –
hermaphrodites
Digestion of Earthworm
Pathway of food:






Pharynx – soil enters
Esophagus Crop-storage
Gizzard- muscular for
grinding soil
Intestines – absorption
anus
Groups of Annelids
Marine segmented worms
Leeches