Download Phylum Arthropoda: Arthropods (crustaceans, spiders, insects)

Phylum Arthropoda
Phylum Arthropoda
Several million species.
Hard exoskeleton.
Phylum Arthropoda: Arthropods (crustaceans, spiders, insects)
Hard exoskeleton, segmented bodies, jointed appendages
Arthropods are the most successful of all animal phyla based on diversity,
distribution, and numbers.
Nearly one million species identified so far, mostly insects.
The exoskeleton, or cuticle, is composed of protein and chitin.
Open circulatory systems in which a heart pumps hemolymph through short
arteries and into open spaces (sinuses).
Aquatic members- gills for gas exchange;
terrestrial members- tracheal system of branched tubes leading from surface
throughout body.
Classes of Arthropods:
A. Class Arachnida:
1. examples– spiders,
scorpions, ticks, mites
2. main body parts – two –
cephalothorax and abdomen
3. number of legs -four pair
( eight )
4. mostly terrestrial
B. Class Insecta – the insects
1. examples – flies, ants, wasps, bees,
beetles, dragonflies, butterflies, cicadas
mayflies, grasshoppers, crickets….
2. main body parts – 3 – head, thorax
and abdomen
3. number of legs – 3 pair (six)
4. mostly terrestrial
C. Class Chilopoda:
1. examples – centipedes
2. main body parts – many segments
3. number of legs – one pair (two)
per segment
4. terrestrial
5. carnivorous
6. head has large antennae
7. first body segment modified
as poison claws
D. Class Diplopoda
1. examples – millipedes
2. many body parts - many
segments
3. number of legs – two pair ( four )
per segment
4. terrestrial, herbivorous
D. Class Crustacea
1. examples – crabs, lobsters, crayfish, shrimp, barnacles
2. body parts – two to three
3. number of legs – five pair ( ten )
usually
4. mostly marine
Class Crustacea
E.g., crabs, lobsters
Almost all are aquatic.
Ca. 40,000 species.
Includes krill eaten by
whales, and daphnia,
copepods, & amphipods in
Lake Erie, pill bugs, etc.