Arthropods Lecture 15 + 16 Flashcards
(25 cards)
Major groups of Arthropods (5)
Trilobites Myriapodia Chelicerata Crustaceans Hexapods
Sub-phylum Myriapoda
Features: body and long repeated trunk
one pair of antennae
many limbs on trunk
(EX) millipedes and centipedes
class Chilopoda
one pair of legs per segment (Centipedes)
flattened or round head and long mandibles
forcipules (no other arthropods)
predatory
class Diplopoda
two pairs of legs per segment (Millipedes)
long, cylindrical bodies
detritivores
Myriapod evolution
oldest known true land animal
largest land invertebrate
first evidence of tracheal air breathing (high O2 levels)
Sub-phylum Trilobita
extinct group of Arthropods
exclusively marine
body- cephalon, thorax and pygidium
body divided into 3 lobes and one pair of antennae
Trilobite fossil record
helped prove continental drift
estimate speciation rates in Cambrian
most diverse group of metazoans in fossil record
sub-phylum chelicerata
body: cephalothorax and abdomen
two pairs of appendages on anterior of cephalothroax: chelicerae and pedipalps
4 pairs of walking legs
classes of chelicerata (3)
Merostomata (horseshoe crabs)
Pycnogonida (sea spiders)
Arachnida (spiders, scorpions, ticks, mites)
Sub-phylum Hexapoda
body: head, thorax and abdomen 1 pair of antennae 3 pairs of mouth appendages 3 pairs of legs on thorax 1-2 pairs of wings
classes of Hexapoda (2)
Entognatha- mouth inside (no wings)
Insecta- in sections (wings)
Myriapods and Hexapods
linked through tracheal air systems
- convergent evolution for life on land
(**insects evolved from freshwater habitats to terrestrial in the Devonian)
Hexapod metamorphosis (2)
Hemimetabolous- instars (no wings, are not sexually mature until last molt)- true bugs (grasshoppers)
Holometabolous- larvae, pupa, adult (beetles, butterflies)
Sub-phylum Crustacea
body: cephalothorax and abdomen
2 pairs of antennae and 3 pairs of mouth appendages
classes of Crustaceans (6)
Branchiopoda Maxillopoda Ostracoda Malacostraca Remipedia Cephalocarida
Branchiopoda
legs flattened (gill-like) most fw, except brine shrimp
Maxillopoda
no appendages on abdomen
barnacles, copepods
Ostracoda
Bivalve shell
“seed shrimp”
Cephalocarida
horseshoe shrimp
Remipedia
primitive and elongate
swim on backs
Malacostraca
most diverse class each segment bears an appendage
Malacostraca classes distinguished by
- number of tagmata (specialized groups of segments with special functions)
- number of segments per tagmatum
- number of thorasic segments covered by carapace
- number of segments fused with the carapace
- presence/absence of moveable spines on telson
shared features in Malacostraca (3)
21 segments
stalked eyes in adults
limbs on abdominal segments
body forms in Malacostraca (3)
shrimp-like
crab-like
lobster-like
