Download Phylum Arthropoda “Jointed Legs”

Phylum Arthropoda
“Jointed Legs”
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Phylum Arthropoda
• Subphylum Crustacea
• Subphylum Chelicerata
• Subphylum Myriapoda
• Subphylum Hexapoda
Phylum Characteristics
1. Bilateral symmetry
2. Head, Thorax, Abdomen or Cephalothorax and
abdomen
3. Jointed Appendages – One pair to each metamere
4. Exoskeleton of Cuticle
- Made of Protein, Lipids, Chitin, and often Calcium
carbonate
- Produced by the epidermis & shed at
intervals. This is called Molting.
Ecdysis: Final stage of molting. Shedding of the exoskeleton.
5. Complex Muscular system
- Striated Muscle for rapid movement of appendages
- Smooth muscle for internal organs
6. Most of the body cavity filled with hemocoel (cavities filled with blood)
7. Open circulatory system with dorsal heart
8. Complete digestive system – Mouth pieces formed from modified
appendages
9. Respiration by body surface, gills, tracheae, or book lungs
10. Excretory systems vary
11. Nervous system – Double nerve chain of ventrally located ganglion.
With well developed sensory organs.
12. Sexes usually separate. Usually internal fertilization
Ecological Relationships:
1. Found in almost every habitat in the world, Desert,
Arctic and Antarctic, deep ocean, high mountain and
all water ways.
2. Carnivorous, Omnivorous, symbiotic, but most are
Herbivorous.
Why are Arthropods So successful?
1. Versatile Exoskeleton
- Highly adaptable body plan.
- Cuticle is produced by an underlining Epidermis.
- Cuticle possesses Chitin a tough, flexible,
lightweight sugar that is insoluble to water,
salts, and weak acids. It allowed the
transition to land.
- Cuticle become proportionately heavier with
increased size therefore there exists an upward limit
to size.
2. Segmentation and appendages for rapid movement
- Typically each somite has a pair of jointed
appendages
- Often this model is highly modified
- Each appendage is a hollow lever with striated muscles
for rapid movement.
- Each appendage is equipped with sensory organs
- Many appendages have been modified for locomotion,
feeding, or food handling
3. Air Piped directly to cells
- Most land arthropods have a system of tracheal tubs that
deliver oxygen directly to the cells and organs for a
fast metabolism.
4. Highly Developed Sensory Organs
5. Complex behavior patterns
- Many posses the ability to learn
6. Reduced Competition through metamorphosis
Phylum Arthropoda: “Jointed Legs”
I. Subphylum Crustacea
Bilaterally symmetrical. What advantages does
bilateral symmetry give the organism?
Class Branchiopoda “Gill Feet”
• Small microscopic Zooplankton with
flattened appendages used for respiration.
Tadpole Shrimp
Fairy Shrimp
Clam Shrimp
Water Fleas
Class Maxillopoda
• A large & diverse group of microscopic
Zooplankton. Exception: Barnacles
Copepods
http://bbclinksmachine.appspot.com/nature/humanplanetex
plorer/survival_skills/foraging#p00dgkmw
Collecting
Goose
Barnacles
Class Malacostraca – LARGEST crustacean
class
Order Euphausiacea
Order Isopoda
Order Decapoda
II. Subphylum – Chelicerata
- Class Merostoma – Horseshoe Crabs have
unsegmented Carapaces, broad abdomen with a
fossil record dating back to the early Triassic
period.
- Class Pycnogonida – Sea Spiders. Common
in all oceans. Have reduced abdomen &
elongated cephalothorax.
Class Arachnida -2 Body segments
(Cephalothorax & Abdomen)& 8 legs. Includes
over 80,000 species including spiders, scorpions,
psudoscorpions, ticks, mites, harvestermen,
daddy-long-legs & others.
Chelicera- Pointed
appendage used to grasp
food.
Pedipalps- Second Pair of
appendages. Function as
touch organs.
III. Subphylum Myriapoda
- Class Chilopoda – Centipedes, active
predators with each of the somites baring a
pair of appendages, Fist appendages after
the head modified into poison claws.
- Class Diplopoda – Millipedes are herbivores
that contain two pairs of appendages for
each abdominal somite.
IV. Subphylum Hexapoda: Class Insecta
1.1 million have been classified. Estimated 30 million
species may still exist.
- Have 3 pairs of walking legs, 3 body parts (head,
Thorax, Abdomen), & usually 2 pairs of wings.
- Without pollinating insects there would be NO
flowering plants or fruit. They have coevolved
http://www.neok12.com/php/watch.php?v=zX555d0570
7a0a7973676102&t=Pollination
together.