Arthropoda III -- Mandibulata Introduction

Question 1

Tagmata Difference (Chelicerae and Mandibulata)

Answer 1

Chelicerata – Prosoma/Opisthosoma
Mandibulata – Head/trunk or Head/thorax/abdomen
Head and thorax fusion is the cephalothorax

Question 2

Anterior Tagma & Appendages

Answer 2

Chelicerata: 1= NA, 2=chelicerae, 3=pedipalps, 4=leg, 5=leg, 6=leg, 7=leg (prosoma)
Mandibulata: 1=NA or Labrum, 2=Antennae, 3=Antennae or NA, 4=mandibles, 5=maxillae(1), 6=maxillae(2) (head)

Question 3

Plesiomorphies of Pancrustacea (3)

Answer 3

2 pairs of antennae
Biramous appendages
Naupilus larva (planktonic)

Question 4

Biramous vs Uniramous appendage

Answer 4

Biramous: Epipod, exopod, endopod, Protopod (Trilobitomorpha, most ‘Crustacea’) – ancestral
Uniramous: Endopod only (Extant chelicerata, Myriapoda, hexapoda) – derived

Question 5

Nauplius larva

Answer 5

No cilia, 3 pairs muscle-operated appendages, single median eye
3 appendages form the 1st and 2nd anterior appendages and mandibles

Question 6

Manton Hypothesis

Answer 6

Uniramian mandible – fusion of ALL articles of ancestral appendages
Crustacean Mandible – derived from coxa (basal article) ONLY

This has been disproven.
Mandibles in BOTH insects and crustaceans derived from basal coxa

Question 7

Myriapoda

Answer 7

Centipedes and millipedes

Question 8

Centipedes

Answer 8

Predators
Poison claws (Appendage of 1st trunk metamere)
Fast runners (high gear myriapods)
Fast active stroke and slow recovery stroke

Question 9

Millipedes

Answer 9

Herbivorous (detritus)
Diplosegments
Fused first and second maxillae (gnathochilarium)
Slow-moving (bulldozers) low gear myriapods
Fast recovery stroke and slow active stroke