Transcript lecture - Fulton County Schools

Animal kingdom
groups (phyla)
What is an animal?

Heterotroph (consumer, not decomposer)

Multicellular

Eukaryote

No cell wall (unlike fungi, plants, and bacteria)

Specialized cells (unlike protists)
Evolution of complexity

Need: sense and chase down food source
Adaptation: nervous / motor systems

Need: break up food and absorb nutrients
Adaptation: digestive system
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Need: deliver oxygen to all cells
Adaptation: circulatory / respiratory systems
Sponges
Sponges
•O2 and food come in through diffusion
•Filter feeds as an adult
Sponges

Unique among animal groups –
1)
No symmetry in overall body plan
2)
No tissues (complex organization of cells)
Sponge reproduction

Sexual – release sperm into water (external fertilization
very common in aquatic animals)

Hermaphroditism – sponges have sperm AND eggs to
increase the odds of reproduction

Offspring can swim to a new location

Asexual fragmentation also possible
Sponges

Simplest animals

Possible colonial protozoan ancestor
Cnidarians
Sea
anemone
Jellyfish
Evolution of radial symmetry

Definiton – can cut in
equal halves more than
one way

Ex: letters “O”, “X”

Purpose – extending
tentacles equally in all
directions (increase food
uptake)
Cnidarian



Basic digestive system
Also basic nervous system (nerve net)
O2 still enters by diffusion
Revolution #1 – active movement

Filter feeding will not be sufficient for larger
animals

Filter feeding will not work on land or in air

2 major adaptations to help organisms sense and
move in their environment
Adaptation #1) Body symmetry

Bilateral symmetry allows for development of
brain region in a central location (head)

Bilateral symmetry  cephalization
Adaptation #2: Body cavity



Coelom is a space inside body (empty / fluid)
Two purposes in evolutionary history:
a) Short-term: something for muscles to
push against to move
b) Long-term: space for larger organs
Not present in all animals (some have lost over
evolutionary time)
Revolution #1 – active movement

Cephalization = “command center” to
coordinate senses and movement
+

Coelom = support for muscle movement
Flatworms
Planarian – not parasitic
Tapeworm – parasitic
Trends in flatworms

No coelom

Why? Many are parasitic

O2 and sugar absorbed in host’s intestine
Tapeworm life cycle
Roundworms
hookworm -- parasitic
Trends in roundworms

Semi-developed coelom (moves a bit more)

Can burrow through skin (walking around
barefoot), also enters through contaminated
food
Not a problem in U.S.
Why not?

Food safety inspections

Good sanitation

Medication widely available
Mollusks
Clam – 2 shells
Snail – 1 shell
Squid – no shell
These are all in the same group!?!
inside of a clam
Mollusk traits

Getting food – filter feeders (clams), grazers
(snails), predators (slugs)

Getting O2 – gills in aquatic mollusks, primitive
lung in snails
Open or closed circulatory system
Open vs. closed
Open
Closed
•No blood vessels
•Blood vessels
•Blood surrounds body’s
organs, delivers O2
•Larger animals
•Smaller animals
Reproduction

Hermaphrodites (both mollusks and segmented
worms)

Aquatic – release sperm and eggs into water

Land – meet and swap sperm, fertilize eggs
inside
Segmented worms
leech
earthworm
Segmented worms

Full coelom (full range of motion, complex
organs inside)

O2 – Gets O2 directly from moist skin,


closed circulatory system with hearts to deliver
Food – blood (leeches), or dirt (earthworms)
Earthworms rule

Swallow dirt, filter out food

Loosen soil, helps to aerate soil for plants

Also fertilizes plants with castings (poop)
Leeches rule

Two chemicals in saliva to help it take blood
from hosts
a)
Anesthetic
b)
Anti-coagulant
Revolution #2 - skeletons

Structural support for larger bodies (remember,
no cell walls in animal cells)

Two varieties:
1) Exoskeleton – outside body (arthropods)
2) Endoskeleton – inside body (echinoderms,
chordates)
Arthropods
Four main classes within this HUGE phylum:
1) Arachnids
2) Crustaceans
3) Centipedes / millipedes
4) Insects
Arachnids
Black widow
Brown recluse
Arachnids
Chigger (flea)
Tick
Scorpion
Crustaceans
Crab
Lobster
Barnacles
Many-footed ones
Centipede
Millipede
Insects
Wasp
Fire ants
Grasshopper
Arthropod traits

Coelomate (I will also stop writing this now)

Segments still (possible connection to
segmented worms)
 Exoskeleton
Exoskeleton

NOT the same as mollusk shell

Functions: 1) protection, 2) prevent water loss
on land (waxy layer)

Problems: Heavy, growth requires molting

Therefore: arthropods tend to be smaller
For respiration…

System for collecting O2 (tracheal tubes /
spiracles)

Open circulatory system
Complex nervous system
Sophisticated sensory / motor control
Compound eye of a fruit fly
Arthropod reproduction

Internal fertilization (mating) in land arthropods

External fertilization in sea arthropods
Echinoderms
sea urchin
sea star
sea cucumber
Echinoderm traits

adults = radial symmetry (live on ocean floor)
 larvae are bilaterally symmetric

endoskeleton
Echinoderm traits

Food – variety of diet (some eat clams, some eat
algae, some filter feed)

Water vascular system (water instead of blood to
carry O2)

Reproduction typical in water
Chordates
All chordates

Have notochord – precursor to vertebral spinal
column (semirigid, filled with fluid)

Vertebrates replace this with a full spinal cord

Some chordates are invertebrates still
Invertebrate chordates
lancelet
tunicate
Endoskeleton advantage

Organisms can grow larger with skeleton inside