Lecture 10: Arthropods I

Question 1

Arthropods

Answer 1

-Segmented body
-Marine, Freshwater and Terrestrial
-More than 75% of known animal diversity

Question 2

4 Innovations of Arthropods

Answer 2

1) Jointed appendages
2) Prominent Exoskeleton
3) Reduced Coelom
4) Growth by Molting

Question 3

1) New Appendages

Answer 3

Jointed for the first time

Question 4

2) Prominent Exoskleleton

Answer 4

-Thick cuticle from the epidermis
-Hardened plates and flexible joints
-Some cuticles become carapaces

Question 5

3) Reduced Coelom

Answer 5

-Not needed as a hydrostatic skeleton anymore
-Used only to surrounds gonads and excretory organs

Question 6

4) Growth by Molting (How to grow with a rigid exoskeleton)

Answer 6

1) Old cuticle separates from epidermis
2)New Cuticle is secreted
3) old cuticle splits and sheds
4) New cuticle hardens

Question 7

Digestive System

Answer 7

Set of modified mouthparts for different feeding modes

Question 8

Nervous System

Answer 8

In general, well developed
-Large brain to coordinate movement
-Many different chemo-sensory organs

Question 9

Respiratory System

Answer 9

Hard cuticle reduces permeability, there is a need for gills and trachaea. Specific organs or structure s depend on groups

Question 10

Excretory System

Answer 10

Insects: Malpighian tubules
Spiders: Coxal Glands
Crustaceans: Green Glands

Question 11

Classification of Arthropods

Answer 11

1) Subphyllum Trilobita
2) Subphyllum Chelicerata
3) Subphylum Crustacea
4) Subphyllum Uniramia

Question 12

Subphyllum Trilobita

Answer 12

450-350 million years ago
Body divided into three regions or tagmata:
-Cephalon or head
-Trunk
-Pygidium

Question 13

Subphyllum Trilobita Appendages

Answer 13

Pair 1: Lost
Pair 2: Antennae
All the rest: Similar and biramous

Question 14

Biramous

Answer 14

Divided in two (endopodite and exopodite)

Question 15

2. Subphyllum Chelicerata

Answer 15

Spiders and horseshoe craps
2 Tagmata
-Cephalothorax
-Abdomen

Question 16

Chelicerata Appendages

Answer 16

Six Pairs of Appendages
-Pair 1: Chelicerae
-Pair 2: Pedipalps
-Other 4: Walking legs

Question 17

Three Classes of Chelicerates:

Answer 17

A. Class Merostomata: Horseshoe crab
B. Class Pycnogonida: Sea Spiders
C. Class Arachnida: Spiders, Scorpions, mites and ticks

Question 18

A. Class Merostomata (Horseshoe Crabs)

Answer 18

-Primitive Class
-All marine
-Large Carapace
-Abdomen with a Telson

Question 19

B. Class Pycnogonida (Sea Spiders)

Answer 19

-All Marine
-Elongated cephalothorax
-Reduced abdomen (looks like one tagmata only)

Question 20

C. Class Arachnida (Spiders, Scorpions, mites and ticks)

Answer 20

-mostly terrestrial species
-prominent wax on cuticle
-Important to people

Question 21

Spiders

Answer 21

-Body with very narrow waist
-Silk producers (nets for dispersion, feeding, eggs)
-Hunter and ambush predators

Question 22

Skorpions

Answer 22

-With terminal stinger
-Tropical, carnivore species
-Some species can be lethal

Question 23

Mites and Ticks

Answer 23

-The most diverse, ecto parasites
-No waist (looks like one tagmata)
-Scavengers

Question 24

3) Subphyllum Crustacea (lobsters and barnacles)

Answer 24

3 regions of tagmata
-Cephalon
-Thorax
-Abdomen

Question 25

Crustacea Appendages

Answer 25

Pairs 1 and 2: antennae
Pair 3-5: Mandibles and Maxillae
Others: Walking, respiration, etc
Appandages are Biramous

Question 26

Crustacea Class Malacostraca

Answer 26

Most diverse class (75% of all crustaceans)
-Includes Decapods (crabs and shrimp)
-5 pairs of legs (chelipeds with claws and chelae
-6 pairs abdominal (pleopods and uropod)

Question 27

Crustacea reproductions

Answer 27

-Most groups are diocious
-Eggs Brooded in most