Transcript Echinoderms, Mollusks & Arthropods

ECHINODERMS, MOLLUSKS &
ARTHROPODS
PHYLUM ECHIDODERMATA = SPINY SKIN
Life-style = free living
= can be: sessile, predaceous, scavengers
 Symmetry = All adults display radial symmetry
= Larvae (immature/infant stage) displays
bilateral symmetry
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Adults = Radial Symmetry
Larvae = Bilateral symmetry
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Ossicles = found in every echinoderm
= internal skeleton made of tiny interlocking
calcium-based plates.
= connected by a catch connective tissue with
adjustable stiffness so they can go from flexible to
stiff in seconds.
= can be covered in poisonous spines to fend off
predators
WATER VASCULAR SYSTEM
Used to grab objects and to move around
 Radials canals radiate off of a ring canal and are connected to
tube-feet.
 The system is sealed so it can use suction to operate
 By using thousands of tube-feet it can exert an immense
amount of force.
 http://www.youtube.com/watch?v=A100m5EpfFI
 http://www.youtube.com/watch?v=HG17TsgV_qI
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Sea star (1) forcefully and slowly open a clam with their tubefeet, (2) throw their stomach into the clam and (3) digest it
while still in the shell.
 The mollusk’s(clam) soft body is easy to digest.
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REPRODUCTION
Sperm and eggs are released into the water and fertilize or
are fertilized by other star’s sperm and eggs.
 The larva(juvenile form) that is produced is bilaterally
symmetric
 Cannot reproduce until it develops into the sexually mature
adult form
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CLASSES OF ECHINODERMS
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Crinoidea= Feather stars and sea lilies
= Use tube feet to filter-feed and bring
food to the mouth
Asteroidea = Sea stars/starfish
=will eat anything(but really like clams)
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Ophiuroidea = Brittle stars
= lack tube feet so use arms to move
= scavengers and predators
Echinoidea = Sea-Urchins and sand dollars
= feed on algae collected by their
spiny(sometimes poisonous) arms
Holothuroidea = Sea cucumbers
= Bilateral symmetry
= Sediment feeders (scavenge small
particles)
PHYLUM = MOLLUSCA
THE MOLLUSKS
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Three main types:
- Cephalopoda. Squid, Octopus
- Tentacles/suckers
- Compound Eyes
- Jet propulsion (siphon)
- Carnivorous
- Inc Sac (protection)
- Developed Brain
- Gastropoda. Snails, Slugs
- Radula: tooth used to scrape food off of
surfaces
- Stalk eyes
- Mantle undergoes torsion
-Bivalves. clams, oysters
- jet propulsion
- 2 shells
- muscular foot
Common Characteristics:
- Mantle: secretes the shell. Sometimes
undergoes torsion(twisting) to produce spiral
shells
- Separation of the sexes (male & female)
- Open and closed circulatory systems
- Gills to breathe under water/Breathe through
skin if on land.
- Muscular foot
PHYLUM = ARTHROPODA
INSECTS, CRUSTACEANS, ARACHNIDS, ETC.
The arthropods = jointed foot
- refers to the jointed appearance of their
exoskeleton.
Advantage: Protection & place for
muscle attachment
Disadvantage: Heavy (limited
growth) & Have to
go through
vulnerable molting
stage to grow out of
old exoskeleton
http://www.youtube.com/watch?v=4QIgW639Oog
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Jointed appendages
 Highly specialized appendages
- Claws, wings, arms, legs,
horns, suckers, antennae,
eyes, etc.
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Complex systems: Nervous, Digestive,
Respiratory, Reproductive,
Excretory, etc.
 Complex Life-cycles: Cicada example
 Separation of sexes remains.
 Why is this slide so boring?
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http://animal.discovery.com/videos/killer-clips-ants.html
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http://www.metacafe.com/watch/973800/strange_faces_of_insects/
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http://www.youtube.com/watch?v=3f7I_HAm4d8
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http://www.metacafe.com/watch/305424/fear_factor_eating_lunch/
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http://www.youtube.com/watch?v=cT4T_5X63ak
CLASS = INSECTA
More members than all other class of animals put together.
 6 legs
 Appendages: wings, mandibles, ovipositor, antennae, legs
claws, etc.
 2 compound eyes
 Head, Thorax and Abdomen body segments.
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CLASS = ARACHNIDIA
8 legs
 Appendages: 2 fangs, 2 pedipalps, spinnarettes
 8 compound eyes
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 Produce silk
- http://www.youtube.com/watch?v=fRTZMhYWKmY&feature=related
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Cephalothorax and abdomen
CLASS = CRUSTACEA
More than 10 legs
 Larger due to lesser effects of gravity under water
 Cephalothorax and abdomen
 2 pair antennae
 Cheliped
 Walking legs and swimmerettes
 Compound stalk eyes
 Gills
 Regeneration
 4-eyes
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