Download Chapter 26 Invertebrate PowerPoint Lecture Notes

Chapter 26
The Higher
Invertebrates
Arthropods
Annelids
This table
represents a
comparison of the
major invertebrate
phyla and their
important
evolutionary
developments.
mouth
coelom
segmented
body
Mollusks
anus
head
bilateral
symmetry,
cephalization
false
coelom
complete
digestive
system
mouth
Roundworms
Flatworms
no coelom (no
cavity between
gut and body
wall)
unsegmented
body
Cnidarians,
comb jellies
radial
symmetry, no
cephalization
saclike gut
Sponges
Success in Symmetry
No symmetry, tissues or organs
• Reproduce sexually and
asexually.
• Spicules
• Osculum
• Colar cells
• Filter feeders
Describe how a
sponge goes
through the process
of filter feeding
animation
Cnidarians
Radial symmetry
Tissues
Nematocysts
3 Classes

Scyphozoans - Jellyfish

Anthozoans - Sea anemones,
corals

Hydrozoans - Hydra
mesogleafilled bell
outer
epithelium
(epidermis)
mesoglea
inner
epithelium
(gastrodermis)
outer
epithelium
mouth
tentacle
mouth
Oral lobe
(armlike
extension of
mouth)
mesoglea
inner
epithelium
Fig. 26.8, p. 428
mouth
epidermis
mesoglea
tentacle
interacting
cells of
nerve net
gastrodermis
sheet of epidermal cells
with contractile properties
Variations On the
Cnidarian Body Plan
Obelia
Both polyp
and medusa
body forms
Acoelomate Animals
and the Simplest Organ Systems
Simple and complex organs

Organs


One or more kinds of tissues,
arranged in a particular pattern &
proportions.
Organ system

When organs interacts with others;
improves performance of a task.
Flatworms

Turbellarians, flukes, &
tapeworms.
Phylum - Platyhelminthes
Flatworms
Bilateral
Cephalized
Acoelomate
Most are hermaphroditic
3 Classes

Turbellarians (planarians)

Trematodes (Flukes)

Cestoda (Tapeworms)
Organ Systems of a
Planarian
Class Turbullaria
Nervous System
Digestive System
Reproductive System
Flukes
Trematoda

Parasitic

Sexual or asexual
phases

At least two hosts
a.
Mates in human host
b.
Leave host feces; hatch as ciliated larvae
c.
Ciliated larvae enter snail host
d.
Multiply asexually; exit forked larvae
e.
Swim and wait for human skin contact
f.
Borrow thru skin; migrate to intestine
Life Cycle of
Schistosoma japonicum
Tapeworms
Cestoda

Parasitic

Scolex

Proglottids

Hermaphroditic
a.
Inverted scolex larvae; muscle tissue
b.
Infected meat eaten
c.
Scolex emerges attaches to intestine
d.
Proglottids form
e.
Fertilized proglottids break off
f.
Cattle ingest eggs or proglottids
Life cycle of Taenia saginata
(beef tapeworm)
Ribbon Worms –
Nematoda
Like flatworms
Bilateral, acoelomate
 Ciliated surface

Unlike flatworms
Circulatory system
 Complete gut
 Separate sexes

Roundworms
Nematoda

Pseudocoelomate

Bilateral

Cylindrical body

Cuticle

Complete digestive
system

Male and female
Phylum - Rotifers
Bilateral
Cephalized
Crown of cilia
Pseudocoelomate
Mostly fresh water
Philodina roseola
Two Early Developmental Modes
of Animals
Protostome & Deuterostome
Differences:

Cleavage
Spiral (diagonal)
 Radial (parallel)

Coelom formation
 Fate of blastopore

Protostome, mouth develops first then anus
 Deuterostome, opposite digestive development

Two Major Divergences
Protostomes (lineage of
coelomate)
 Mollusks, annelids, arthropods
 Spiral cleavage
 First embryonic opening -->
mouth
 Coelom arises from spaces in
mesoderm
Deuterostomes




Echinoderms, chordates
Radial cleavage
First embryonic opening -->
anus
Coelom arises from
outpouchings in gut wall
How a coelom
forms in a
protostome
embryo:
pouch will form
mesoderm
around coelom
developing gut
How a coelom
forms in a
deuterostome
embryo:
coelum
solid mass of
mesoderm
developing gut
In-text, p. 436
Slide 31
The Amazing
Mollusks
(Phylum Mollusca)
A Sampling of
Molluscan Diversity
Mollusca

Soft body

Secrete Shell

Mantle

Tissue over
visceral mass that
secretes shell

Fleshy foot

Gills
Important
molluscan
characteristics:
Second largest group of
invertebrates.
Soft-bodied.
Bilateral symmetry.
Breathe through gills.
Most species have:
 A head
 A “foot”
 A visceral mass




Gut (complete)
Heart
Kidneys
Reproductive organs
Some have eyes & tentacles.
Most have a shell or a remnant.
Many have a radula for feeding.
Mollusk Groups
Gastropods

Snails, slugs &
nudibranchs
Chitons

“Univalves”
Bivalves

Clams, oysters,
scallops & mussels
Cephalopods

Octopus, squid,
cuttlefish, nautilus
Largest group of mollusks.
Crawl about on their “foot”.
Many have coiled shells.
Most show torsion – a
twisting realignment of
body parts.
Secrete mucus to keep
skin moist, reduce friction
when crawling.
Scrape food (mainly algae)
off substrates by using a
file-like radula.
Often serve as
intermediate hosts for
parasitic worms.
The Gastropods
The Gastropods
Torsion of the Viscera
mouth
anus
gill
Cilia near this
region creates
currents that
sweeps waste
away.
excretory organ
anus
gill
heart
digestive
gland
mantle cavity
(secretes the
shell)
stomach
heart
stomach
shell
radula
mantle
mouth
radula (magnified)
foot
The Chitons
Slow-moving or sedentary
(sessile).
Most use a radula to scrape
algae off surfaces (like
Gastropods).
Have a large, broad muscular
foot.
Foot allows chitons to cling to
surfaces tightly.
Dorsal shell divided into eight
plates.
Mantle acts like suction cup,
helping chiton stay attached to
substrate.
Include clams, oysters,
scallops & mussels.
Bivalve means “two shells”.
Large foot specialized for
burrowing.
Gills used for respiration and
trapping food particles.
Water is drawn into mantle
cavity through inhalant
siphon, filtered through gills
and expelled through
exhalant siphon.
Some bivalves (like scallops)
can swim by clapping their
valves together.
The Bivalves
retractor muscle
retractor muscle
mouth
mantle
gill
water flows
out through
exhalant
siphon
palps
water flows
in through
inhalant
siphon
foot
shell
Cilia on gills allow for suspension
feeding by creating a movement of water
through siphons
The Cephalopods
•Most highly developed brains of all
invertebrates (eyes; learning &
memory possible).
•Beak-like crushing jaws.
•Some have venomous bites.
•Move swiftly via jet propulsion.
•Only mollusks with closed
digestive gland
circulatory systems.
esophagus
stomach
kidney
brain
internal shell
arm
jaw
mantle
reproductive
organ
radula
ink sac gill
siphon
anus
accessory heart
(Speeds up circulation)
heart
tentacle
Cephalopods have separate sexes!
The Annelids
(Phylum Annelida)
Polychaetes
tentacles
eyes
parapods
Bodies divided into
segments.
Bilateral symmetry.
Bristles on each body
segment (except leeches).
These can be retracted and
provide traction for
burrowing.
Feed upon decomposing
organic material.
Thin cuticle allows gas
exchange through skin.
Two muscle types, circular &
longitudinal.
Complete digestive tract,
closed circulatory system,
brain & ventral nerve cord.
Excretory nephridia.
The Annelids
(Phylum Annelida)
Earthworm cross-section
circular muscles
dorsal blood vessel
longitudinal muscles
intestine
coelom
typhlosole
Hydrostatic
skeleton
intestinal cavity
seta (retracted)
How do
earthworms move?
• circular muscles
• longitudinal
muscles
• hydrostatic
skeleton
• setae
cuticle
ventral blood vessel
nerve cord
nephridium
Regulates fluid balance
Thin & flexible;
permits gas
exchange
bladderlike storage region of
nephridium
nephridium’s thin loop
reabsorbs some solutes,
relinquishes them to blood
blood
vessels
body
wall
funnel (coelomic fluid
with waste enters here)
external pore (fluid containing
wastes discharged here)
Earthworm
excretory system
Earthworm circulatory system
aortic arches
(hearts)
blood vessels
(ventral and dorsal)
Earthworm digestive system
pharynx
intestine
mouth
esophagus
crop
(storage)
gizzard
(mashing)
Earthworm nervous system
brain
ganglion
nerve cord
Parasitic Annelids
Before
feeding
After
feeding
Leeches are one of the few
annelids without bristles.
Have suckers at both ends of
body to help with movement.
Have razor-sharp jaws used
to make incision in host’s
skin.
Secrete anticoagulant
through mouth to prevent
host’s blood from clotting.
Gut has many side branches
for storing victim’s blood.
One feeding can last leech
for one year.
Like all annelids, leeches
have segmented bodies.
The Incredibly Diverse Arthropods
(Phylum Arthropoda)
Over 1 million different species, to
date. Largest group of animals.
New species discovered every
week!
Probably evolved from the annelids.
Inhabit nearly every region of Earth.
Four major lineages:


Did you know that
arthropods demonstrate the
MOST diversity


Trilobites (now extinct)
Chelicerates (spiders, scorpions, ticks)
Crustaceans (crabs, crayfish, shrimp)
Uniramians (insects, centipedes,
millipedes).
Arthropod evolutionary success is due
to six primary adaptations:
A hardened exoskeleton.
Specialized segments.





Feeding
Sensing
Locomotion
Sperm transfer
Silk spinning
Jointed appendages (only arthropods modified
for flight)
Specialized respiratory structures.
 Gills
 Tracheas (pores to tubes which allows for
flight)
Efficient nervous system & highly developed
sensory organs (esp. site; compound eye)
Division of labor in the life cycle.
Types of
Metamorphosis
Growth and molting
egg
young
egg
nymphs
adult
Incomplete metamorphosis
adult
Complete metamorphosis
egg
larvae
pupa
adult
The exoskeleton: a coat of armor!
Made of chitin & protein,
it’s light & flexible.
Restricts water loss.
Provides support &
defense.
Allows internal muscle
attachment, enabling
greater strength for
organisms.
Some disadvantages:
Restricts size increases.
Must be shed (molted)
periodically (see at left).
Restricts range of
motion.
Except for horseshoe crabs,
all are terrestrial.
Most are predators, some
(ticks) are parasitic.
Several pairs of simple eyes.
Four pairs of walking legs.
Chelicerae (fangs) in spiders
used to inject venom.
Pedipalps used for holding &
tasting food.
No antennae.
Spiders produce silken webs.
Book lungs for respiration.
Scorpions- tip of abdomen
modified into stinger with
venom gland.
The Chelicerates
eyes
digestive gland
heart
Malpighian tubule
brain
poison
gland
anus
book
lung
pedipalp
mouth
sperm receptacle
chelicera (fangs; inflict wounds & inject
ovary
silk gland
spinners
Ectoparasites of vertebrates.
Feed on blood.
Carry bacteria responsible
for causing Rocky Mountain
Spotted Fever and Lyme
Disease (shown below).
Ticks
female
male
Shrimp, crayfish, crabs,
The Crustaceans
lobsters & pillbugs.
16 to 20 body segments.
Head & thorax fused into a
cephalothorax.
Two pairs of antennae.
Compound eyes on stalks.
Three pairs of mouthparts.
Five pairs of walking legs.
First pair of walking legs
modified into powerful
chelipeds for defense.
Gills used for respiration.
antennae
(two pairs)
food-handling
appendages
(three pairs)
one of two compound eyes
fused segments of
cephalothorax
segments of
abdomen
swimmerets
tail fin
first leg
(cheliped)
five walking legs (five pairs total)
External crayfish
anatomy
Note: 2 pairs of antennae; unique in
arthropods
Millipedes
4 legs per body segment.
Cylindrical body shape.
Feed on decaying plants.
Secrete foul-smelling
chemical for defense.
Centipedes
2 legs per body segment.
Flattened body shape.
Fast, aggressive carnivores.
Have fangs & venom glands.
The Insects
Body divided into head, thorax,
abdomen (thorax adapted for
locomotion)
One pair of antennae.
Locomotion: three pairs of walking
legs, usually one pair of wings.
Compound and simple eyes.
Breathe through spiracles into
tracheal tubes.
Malpighian tubules remove nitrogen
wastes from blood (conserves water)
Nitrogen wastes combined with solid
waste to conserve water.
Only winged invertebrates.
Aggressive competitors with man.
Insect feeding adaptations
Chewing
(grasshopper)
Sipping or
Siphoning
(butterfly)
Sopping
(housefly)
Piercing &
Sucking
(mosquito)
Arthropods, esp. insects,
owe their evotionary
success to …
Hardened exoskeleton
Specialized segments with joined
appendages
Efficient respiratory & sensory structures.
Division of labor in their life cycles.
Insect Life Cycles: Post Embryonic
a. Growth and
molting
• Embryo
• Nymph
• Larvae
egg
young
adult
b. Incomplete
metamorphosis
• Pupae
• Adult
Note:
egg
nymphs
adult
c. Complete
metamorphosis
• Use different
resources at different
stages of development.
• Winged; most
successful
• Only invertebrate
with wings
egg
larvae
adult
• Check out the diversity
of the appendages
among the following
insects.
• How does this
diversity help insects in
term of feeding and food
supply?
The Puzzling Echinoderms
(Phylum Echinodermata)
Echinoderm means
“spiny skinned”
All contain calcium spines,
spicules or plates in their
body walls.
Radial & bilateral symmetry.
No brain, but nervous
system present.
Water vascular system with
tube feet for locomotion.
Swallow prey whole or push
stomach out of body onto
prey, partially digesting it
before swallowing it.
upper
stomach anus
gonad
ossicle (stiffening,
support structure)
lower
stomach
coelom
digestive gland
eyespot
the water-vascular system
sieve plate or
madreporeite
ampulla
ring canal
tube feet
Click to view water vascular system