Transcript Simple Animals

Simple Animals
L2 Biology
A breakdown of the animal kingdom
reveals many phyla
SIMPLE
ANIMALS
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Porifera - sponges
Cnidaria – jellyfish, coral
Platyhelminthes – flat worms
Nematoda – round worms
Annilida – segmented worms
Mollusca – clams, snails, squid
Echinodermata - starfish
Arthropoda – insect, spider, crustacean
Chordata – frogs,fish, humans
Cnidaria
(formerly called Coelenterata)
• All have stinging cells (cnidocytes)
• Two body forms:
– Medusa – like a jelly fish
– Polyp – like a hydra
• Radial symmetry
• Have tentacles
Cnidarian Cnidocyte
Have you ever been stung by jellyfish?
Cnidarian Life Cycle – medusa and
polyp alternate
medusa
polyp
egg
larva
Polyp body form
Hydra on water plants
Hydra Anatomy
mouth
tentacles
testis
bud
Gastrovascular
cavity
ovary
Basal disc
Coral is actually a colony of polyps, most of which are the size
of a single hydra – they just make a case around them for their
home.
Here are a variety of anemones – polyp body form
- Platyhelminthes
• Have flat bodies
• Some are parasitic
• Most are free-living
These are free-living flatworms
Planaria
Scolex – head with hooks and suckers
Tapeworms – the ultimate parasite –
only highly developed system is its
reproductive system hermaphroditic
Phylum Nematoda - roundworms
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Mouth – digestive tube – anus
Most free-living
Some parasitic
Look like threads in the
microscope
Some are parasitic to humans
• Trichina
• Hookworm
– From
• Enters through soles
undercooked
of feet
– Larvae in human
feces
– Causes fatigue –
may cause physical
and mental
retardation if
children have it
pork
– Causes severe
muscle aches
when larvae
migrate from
intestine to
muscles
• Filaria
•Causes
elephantiasis
•No treatment
•Carried by
mosquitoes
This lesion is caused by a nematode infestation
-Caused by filaria – the worm
blocks the lympatic vessels and
the area swells with lymph. No
treatment is available.
Phylum Annelida
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Segmented worms
Includes earthworms and leeches
Most are free-living
Complex body with organ systems
hermaphroditic
Leech
Earthworm
Earthworm
Anatomy
Phylum Arthropoda
•Jointed legs
•Chitinous exoskeleton
•Ventral nerve cord
•Must molt to grow
•Some undergo metamorphosis
•Includes insects, crustaceans, spiders, millipedes and
centipedes
Class Insecta
•Six legs
•May have wings
•Undergo metamorphosis
•Varied mouthparts
•Breathe using spiracles
Class Arachnida –
8 legs, no antennae,
simple eyes, chelicerae,
tick
scorpion
Dust mites
spiders
CCrustacea –
two body regions = cephalothorax
most live in water
Millipedes and Centipedes
The
End