Three Domains of Life
Kingdom Animalia
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Eukaryotic (Domain Eukaryota)
Multi-cellular (unlike most Protists)
Lack cell walls (unlike Plants and Fungi)
Heterotrophic, by ingestion – Animals
obtain their nourishment by ingesting
other organisms (unlike Fungi)
Kingdom Animalia
• Most animals are mobile
• Sexual reproduction; haploid cells fuse
directly to produce zygote, and no
alternation of generations
• Tissues – cells are organized into
structurally functional tissues
Kingdom Animalia
• Radial symmetry –
body parts arranged
around a central axis
(simple)
• Bilateral symmetry –
body has a right and
a left half that are
mirror images of
each other
(advanced)
Kingdom Animalia
• Evolution of a body cavity enabled the
evolution of supporting organ systems and
a means for distributing materials
• The body cavity – a space surrounded by
mesodermal tissue formed during
development
• Three germ layers: Ectoderm (outside),
Mesoderm (middle), and Endoderm (inside)
Kingdom Animalia
• Pseudocoelomates
move nutrients and
wastes through
pseudocoel
• Coelomates developed
a circulatory system;
blood carries oxygen,
nutrients, carbon
dioxide and wastes
through (and out of)
body
Kingdom Animalia
• Circulatory system of Coelomates can be
open or closed
• In an open circulatory system, blood mixes
with body fluids; bathes organs and cells
directly; common to molluscs and
arthropods
• In a closed circulatory system, the blood
never leaves a system of blood vessels
and is pumped by the heart; common to all
vertebrates, annelids and cephalopods
Kingdom Animalia
• Segmentation of body parts
– Succession (redundancy) of segments
– Enables specialization of body segments
– Individual segments may move independently
to facilitate locomotion
– In redundant segmentation, each segment
contains most or all of the adult organ
systems, such that damage to any one
segment is not fatal to the organism
• “Bilaterians exhibit two main types of
development” – page 626
...let’s come back to this (ignore for now)
Kingdom Animalia
• Taxonomy (Domain Eukaryota, Kingdom
Animalia, Phylum….)
Phylum Porifera (Sponges)
• The simplest of animals
• No nervous, digestive, or circulatory
systems
• Sessile
• Lack germ layers
• No defined
symmetry
Phylum Cnideria
• Nematocysts – stinging cells
• Radial symmetry
• “Jellyfish”, Corals, Sea anemones
Phylum Ctenophora (Comb jellies)
• Colloblasts – sticky cells
• Strictly marine
• Largely bioluminescent
Phylum Platyhelminthes
(Flatworms)
• No body cavity
• Half of all flatworms are parasitic (flukes,
tapeworms, etc)
Phylum Nematoda (Round worms)
• Pseudocoelomates
• Can be free-living or parasitic
http://www.attra.org/images/nematode/nematode.jpg
Guinea worm
Phylum Annelida
(Segmented worms)
• Coelomates
• Oligochaetes (earthworms) and
Polychaetes (bristle worms)
Phylum Mollusca
• Mantle – secretes shell; forms siphon and
external flaps
• Bivalves (clams, mussels, etc), Snails,
Squid, Octopus, Sea Slugs
http://www.flickr.com/photos/ccahua/109008198/
http://www.flickr.com/photos/sabinche/424078457/
Phylum Arthropoda
• “Jointed foot”; jointed limbs, rigid
cuticle/exoskeleton
• Insects, Arachnids, Crustaceans, and
others – VERY SUCCESSFUL!
http://www.flickr.com/photos/j-a-x/98046000/
Phylum Echinodermata
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Strictly marine
Deuterostomes (we’ll come back to this)
“Spiny skin”
Includes sea stars, sea urchins, brittle
stars
Phylum Chordata
• Includes all vertebrates (Subphylum Vertebrata)
• All have (at one stage of their life cycle)
– A notochord – a flexible rod; “backbone”
– A hollow, dorsal nerve cord; develops into spinal
cord and brain
– Pharyngeal slits* – filtering apparatus for feeding
– An endostyle* – longitudinal ciliated groove in
pharynx, produces mucus to capture food particles
– A post-anal tail*
*only present during embryonic stage in advanced
vertebrates
All Chordates have all four of these
characteristics at some time in their lives
Phylum Chordata
• Includes 2 invertebrate groups (no
vertebrae)
– Urochordates – only the larvae has a
notochord and nerve cord, adults usually lose
tail; includes Tunicates and Salps (marine)
– Cephalochordates – notocord persists
throughout animal’s life; includes Lancelots;
the closest relatives to the Vertebrates
Subphylum Urochordata (Tunicate)
Subphylum Cephalochordata
(Lancelets)
Subphylum Vertebrata
• A vertebral column – encloses and
protects the dorsal nerve cord
• A distinct head – houses sensory organs
• Endoskeleton – made of cartilage or bone
• Internal organs – liver, kidneys, endocrine
glands, heart and closed circulatory
system, etc.
Subphylum Vertebrata
Subphylum Vertebrata
• The earliest vertebrates appeared in the
oceans ~ 0.5 billion years ago (Cambrian
period)
Jawless
fishes
Cartilaginous
fishes
Bony fishes
Jawless fish (Lampreys)
Class Chondrichthyes
(Cartilagenous)
Class Chondrichthyes
• A light, flexible skeleton and paired fins
made them superior swimmers
• Sharks were among the first vertebrates to
develop teeth
Bony Fishes
• Evolved at same time as sharks (400
million years ago)
• Heavy, internal skeleton made of bone
• Possess a swim bladder and an
operculum
• Swim bladder – gas-filled sac enables fish to
control their bouyancy
• Operculum –hard plate that covers gills, flexes to
permit water pumping
Bony Fishes
Amphibians
• The first vertebrates to make it to land
• Evolved ~300 million years ago
Class Reptilia
• Reptiles evolved ~250 million years ago
• Ectothermic (“cold-blooded”)
• Evolution of the amniotic egg
– Watertight, but permeable
– Allows gas exchange and waste removal
– Yolk sac provides food
• Includes the dinosaurs!
Class Reptilia
Class Aves (Birds)
• The most diverse group of all vertebrates
• Like reptiles, have amniotic eggs and
scales (on legs)
• Feathers – enable flight and conserve heat
• Flight skeleton
– Bones are thin and hollow
• Evolved directly from
dinosaurs?
Class Mammalia
• Hair – keratin-rich fibers; provides
insulation, camouflage, and sensory
structure
• Mammary glands in females – secrete milk
• Endothermy (“warm-blooded”)
• Four-chambered heart
• Evolved ~220 million years ago
Class Mammalia
Subclass Prototheria
• The “Monotremes”
– Have single opening for
digestive and reproductive
tracts
– Only 3 extant species –
short and long-nosed
echidna and duck-billed
platypus
Class Mammalia
Subclass Theria
• Includes marsupial and placental animals
– Marsupials – pouched animals; shell-less egg,
embryo is nourished by yolk and after birth
crawls into marsupial pouch where it latches
onto nipple and continues to develop
– Placental – includes most living mammals;
produces a true placenta that nourishes
embryo throughout its development
• Modern humans first appeared in Africa
~600,000 years ago (Homo sapiens)