Transcript File - MR. Hill`s class

PHYLUM ARTHROPODA
Largest phylum of the animal kingdom
Arthropod species account for ~ 75% of all animal species
Evolved ~ 600 mya
http://www.youtube.com/watch?v=h8DXzjvnzPk&feature=related
Taxonomy
General Characteristics
All arthropods share three general characteristics:
1. Jointed appendages
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such as jointed legs and antennae
arthropod actually means “jointed foot”
General Characteristics
2. Exoskeleton
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external skeleton that helps protect and support
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has three layers
– outer = wax to repel water and prevent from desiccating
(drying out)
– middle = protein + chitin + calcium carbonate for
protection (like armour plating)
– inner = protein + chitin, flexible protection (like chain
mail)
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limits maximum size of arthropods as exoskeletons become
very heavy as the animal gets bigger
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does not grow, must be molted and then re-grown
General Characteristics
3. Segmented Body
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Each segment generally contains at least 1 pair of
appendages
– Arthropod success is explained, in part, due to the
diversity of their appendages
• Legs
• Antennae
• Pincers and claws
• Stingers
• Wings
• Jaws
• Paddles
• Gills
• Spinnerets (for spinning webs)
General Characteristics
3. Segmented Body
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Sometimes different segments are fused together to form
tagmata which may be specialized for
– Feeding
– Locomotion
– Reproduction
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Body structure often includes (especially all insects):
– Head: arthropods are highly cephalized
– Thorax
– Abdomen
Other Common Characteristics
Open Circulatory System
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Have a hemocoel = cavity containing internal organs
– Hemolymph (essentially blood) is not contained in
vessels, simply bathes the organs within the hemocoel
Well Developed Nervous System
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ladder-like
– 2 ventral nerve cords (rails) linked by cross nerves
(rungs)
Well Developed Respiratory System
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Terrestrial arthropods have lungs or air sacs
Aquatic arthropods have gills
Taxonomy
Taxonomy –Subphylum Trilobita
An extinct subphylum characterized by:
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very long antennae
many segments
hard exoskeleton
Taxonomy –Subphylum Uniramia
An extant (currently living) subphylum characterized by:
• one-branched (or non-branched) appendages
• have antennae and mandibles (jaws)
• appear to have evolved on land
Three Main Classes
• Class Chilopoda
– Centipedes with flattened body and 1 pair of legs per
segment
• Class Diplopoda
– Millipedes with rounded body and 2 pairs of legs per
segment
• Class Insecta
– Flies, grasshoppers, bees, wasps, ants, buttlerflies, moths
and beetles that have madibles, antennae, unbranches
appendages, 6 legs, and often one or two pairs of wings
Taxonomy –Subphylum Chelicerata
An extant (currently living) subphylum characterized by:
• lack of antennae
• Presence of pincer-like mouthparts called chelicerae
Three Main Classes
• Class Xiphosura
– Horseshoe crabs
• Class Arachnida
– Spiders, scorpions, mites and ticks that have a
cephalothorax and abdomen and 8 legs
Taxonomy –Subphylum Crustacea
An extant (currently living) subphylum characterized by:
• two pairs of “feelers” on head
• have branched appendages
• mostly aquatic including copepods, water fleas, barnacles,
crab, shrimp, crayfish, lobster
• terrestrial exception – pill bugs/rolly-pollies
Insects-Chapter 39
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http://www.youtube.com/watch?v=Na5ms4UxU0s
http://www.youtube.com/watch?v=Mb3OQPT3qbU&feature=related
http://www.youtube.com/watch?v=oWOC8trquFo&feature=related
Classification of Insects
• Phylum Arthropoda
– Subphylum Uniramia
•Class Insecta
• Entomology = the study of insects
• Entomologist = scientists that study insects
Characteristics of Insects
• Segmented body
– divided into three tagmata:
• Head
• Thorax
• Abdomen
• Jointed appendages
• Exoskeleton
Characteristics of Insects
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Most insects are small
They have jaws = mandibles
One pair of antennae on head
Thorax has three pairs of jointed legs
Many species one or two pairs of wings
Abdomen composed of 9-11 segments
INSECT DOMINATION!
• = 80% of all organisms that scientists have classified and
named
• inhabit almost every imaginable niche and ecosystem
on the planet including the Arctic
WHY INSECT DOMINATION?
• exoskeleton
• diverse jointed appendages
• small
• rapid and numerous reproduction
• incomplete and complete metamorphosis
Insects and People
• The Negative Effects
– crop damage
– spread disease via bites
•some fleas carry plague
– damage buildings (Termites)
– allergies to bites
Insects and People
The Positive Effects
• Insects play vital role in almost all terrestrial and freshwater
environments
– Serve as food for many other animals
• Cross pollinate plants
– Estimated that insects pollinate 40% of worlds flowering
plants
• Provide us with:
– honey
– wax
– silk