Chapter 14, The Animal Kingdom

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Chapter 14, The Animal Kingdom

• Biology, 2008

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Chordates
Echinoderms
Arthropods
Annelids
Coelomate Ancestry
Mollusks
Rotifers
Roundworms
Bilateral Ancestry
Flatworms
Radial Ancestry
Cnidarians
Sponges
Multicelled Ancestry
Single-celled, protistanlike ancestors
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posterior
dorsal
Radial symmetry
ventral
anterior
Bilateral symmetry
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Porifera - Sponges

• No symmetry
• No organs
• The least complex animals
• Aquatic in fresh and marine environments

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water out
glasslike structural elements
amoeboid cell
pore
semifluid matrix
central cavity
flattened surface cells
water in
flagellum
microvilli
nucleus
Body Plan of a Sponge
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Venuss flower basket (Euplectella)
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Cnidaria

• Radial symmetry
• Body has only 2 cell layers
• Mouth surrounded by tentacles with stinging cells
• Aquatic, FW and marine
• Include jellyfish, corals, sea anemones, hydra
• Some are motile, and all have a very simple
  nervous system
• Respiration direct gas exchange with aquatic
  surroundings

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There are two Cnidarian body plans
Polyp
outer epithelium (epidermis)
mesoglea (matrix)
inner epithelium (gastrodermis)
Medusa
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reproductive polyp
female medusa
male medusa
sperm
ovum
Life cycle of Obelia
feeding polyp
zygote
planula
polyp forming
branching
one branch from a mature colony
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Flatworms - Platyhelminthes

• Body has 3 cell layers ectoderm, mesoderm and
  endoderm
• Bilateral symmetry
• Parasitic and free -living aquatic (fw and
  marine) and terrestrial tapeworms, flukes, and
  Planaria
• Digestive system with one opening
• Primitive nervous system
• Hermaphroditic
• Respiration through skin

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pharynx (protruded)
protonephridia
flame cell
nucleus
cilia
fluid filters through membrane folds
Planaria, a free-living flatworm
opening of tubule at body surface
flame cell
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brain
nerve cord
genital pore
testis
penis
oviduct
ovary
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b A definitive host eats infected, undercooked
beef
a Larvae become encysted in intermediate host
tissues
c Scolex of larva attaches to intestines wall
d Many proglottids form by budding
f Cattle may ingest embryonated eggs or ripe
proglottids to become intermediate hosts
e Ripe proglottids containing fertilized eggs
leave host in feces
Tapeworm life cycle
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Roundworms - Nematoda

• Digestive system with mouth and anus (complete)
• Separate sexes
• Aquatic and terrestrial, free living and
  parasitic
• Body cavity gives tube within a tube
  construction
• Respiration through skin, no circulatory system

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Body Plan of a Roundworm
gonad
pharynx
intestine
eggs in uterus
anus
false coelom
muscularized body wall
Caenorhabditis elegans
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 Life cycle of Schistosoma japonicum
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Mollusks - Mollusca

• Often but not always have external shell
• Includes clams, oysters, snails, slugs, squid,
  octopus, scallops, chambered nautilus
• Body is soft with bilateral symmetry
• Nervous system, circulatory system, respiratory
  system
• Some have excellent sense organs and large
  brains, and can learn easily.

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Body Plan of a Snail
anus
gill
mantle cavity
excretory organ
heart
digestive gland
shell
stomach
mantle
radula
foot
Do not post photo to Internet
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mouth
retractor muscle
left mantle
retractor muscle
water flows out through exhalant siphon
water flows in through inhalant siphon
foot
palps
left gill
shell
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Body Plan of a Cuttlefish
esophagus
stomach
kidney
digestive gland
brain
arm
jaw
mantle
reproductive organ
internal shell
siphon
ink sac
heart
accessory heart
tentacle
radula
anus
gill
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Segmented Worms - Annelida

• Body composed of many identical segments. Allows
  more specialization
• Aquatic or terrestrial
• Includes clam worm, feather worms, leeches, and
  earthworm.
• These animals have all systems, and are quite
  complex. They are most likely the ancestors of
  the Arthropods, the most successful Phylum of
  animals on Earth.

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jaws
toothlike structures
pharynx (everted)
antenna
palp (food handling)
tentacle
eyes
chemical-sensing pit
parapod
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coelomic chambers
pharynx
mouth
esophagus
crop (storage)
gizzard (mashing)
Earthworm Digestive system
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Earthworm Nervous system
brain
nerve cord
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Earthworm Circulatory system
hearts
blood vessels
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bladderlike storage region of nephridium
nephridiums thin loop reabsorbs some solutes,
relinquishes them to blood
blood vessels
Excretory system
body wall
external pore (fluid containing wastes discharged
here)
funnel (coelomic fluid with waste enters here)