phylum arthropoda

Question 1

basic characteristics of arthropods (5)

Answer 1

1. metamerism and tagmosis
2. exoskeleton (chitin)
3. muscle arrangement
4. coelom
5. moulting / sensilla

Question 2

functions of the exoskeleton in arthropods (5)

Answer 2

1. protection
2. support
3. maintains shape
4. transmits force of muscle contraction
5. minimizes dessication (terrestrial)

Question 3

moulting in arthropods

Answer 3

periodic

• new exoskeleton secreted beneath the old one
• the endoskeleton is degraded/ destroyed ; exoskeleton is ‘broken’ and arthropod crawls out
• soft new exoskeleton “bumps” water into itself to gain room for growth

Question 4

what do most arthropods use to sense their environment

Answer 4

mechanoreceptors: sensory bristles on the surface called sensilla - appear as hairs

Question 5

general characteristics of subphylum chelicerata (4)

Answer 5

1. two tagmata: prosoma and opisthosoma
2. # of appendages: 6 prs. prosoma; opisthosoma variable
3. 1st pair of appendages = chelicerae
4. 2nd pair of appendages = pedipalps

Question 6

Common name: Class Merostomata

Answer 6

horseshoe crabs (phylum arthropoda, subphylum chelicerata)

Question 7

2 defining characteristics of class merostomata

Answer 7

1. opisthosoma appendages modified as book gills

2. telson - elongated spike at terminal end of body

Question 8

3 classes of chelicerates

Answer 8

1. merostomata - horseshoe crabs
2. arachnida - spiders and scorpions
3. pycnogonida - sea spiders

Question 9

4 groups of pancrustaceans

Answer 9

1. hexapoda
2. malacostraca
3. copepoda
4. cirripedia

Question 10

4 groups of malacostracans

Answer 10

1. euphausiacea - krill
2. stomatopoda - mantis shrimp
3. decapoda
4. peracardia - amphipods and isopods

Question 11

4 groups of decapods

Answer 11

1. caridea - shrimps
2. astacidea - lobster & crayfish
3. anomura - hermit, king crabs etc.
4. brachyura - true crabs