arthropod - major groups

Question 1

major groups of arthropoda

Answer 1

• crustacea - crabs, shrimps, lobsters, barnacles
• hexapoda - insects and their relatives
• trilobitomorpha - trilobites ( extinct )
• cheliceriformes (chelicerata) - spiders, scorpions
• myriapoda - many legged arthropods; centipedes and their kin

Question 2

the crustacea

Answer 2

no range of plants or animals on the exhibit the range of morpohological diversity seen among crustacea

• crabs, lobsters and their allies
• cambrian marine origin
• 67,000 described living species
• 100um - 3m

Question 3

unifying crustacean characteristics

Answer 3

• 5 segmented head
• trunk region usually divided into 2 tagmata
• biramous limbs
• carapace
• nauplis larva

Question 4

crustacean bauplan : head

Answer 4

5 segmented head ( with two pairs of antennae mandibles and two pairs if secondary mouthparts ( maxillae ))

Question 5

palp (palpus)

Answer 5

each of a pair of elongated segmented appendages near the mouth of an arthropod

Question 6

crustacean bauplan : trunk

Answer 6

trunk region usually divided into 2 tagmata :

• thorax
• abdomen

Question 7

crustacean bauplan : biramous limbs

Answer 7

biramous ( two-branched ) limbs

remipedia - ‘primative’ body design

Question 8

crustacean bauplan : carapace

Answer 8

carapac or cephalic shield ( reduced in some groups )

Question 9

crustacean bauplan : nauplius larva

Answer 9

planktonic nauplius larva ( lost when development is direct)

nauplius has :
- median simple eye
- 3 pairs of setose appendages (become 2 pairs
of antennaea and mandibles
- suppressed in many groups whoch have direct
development

Question 10

crustacean diversity

Answer 10

three aspects :

1. diversity of segments in an adult of one species
   - up to 14 types of segments
2. segment diversity between species
   - a particular body segemnt takes many form in differet taxa
   - also tagmatisation can become extensive ( thoratic segments become associated with the head, and their appendages function as accessory mouthparts - macillipeds )
3. diversity of segment morphology during ontogeny