Arthropoda

Question 1

Name the 13 traits of Phylum Arthropoda

Answer 1

1. Segmented protostomes with teloblastic growth
2. Strong heteronomy - has tagma
3. Complete gut
4. Modified metanephridia
5. Adult coelom greatly reduces - has an endsac
6. Open circulatory system - hemocoel
7. Their heart is dorsal and ostiate
8. Thick cuticle - sclerites
9. Molting process - ecdysis
10. Jointed appendages with intrinsic musculature
11. Annelid-like nervous system - compound eye
12. No functional cilia - cilia is lost
13. Intersegmental muscle bands (not sheets) - no circular muscles

Question 2

What are the 3 synapomorphies of Arthropoda?

Answer 2

1. Thick cuticle
2. Jointed appendages with intrinsic musculature
3. Compound eye

Question 3

What are the 5 major subgroups of Arthropoda?

Answer 3

1. Trilobitomorpha - trilobites. Extinct
2. Crustacea - example of a paraphyletic group - ancestors and some of its descendants
3. Cheliceriformes - liquid feeders (spiders, mites, scoprions, etc.)
4. Hexapoda - six legs (insects, etc.)
5. Myriapoda - centipedes (100) and millipedes (1000)

Question 4

Pleopods

Answer 4

Swimming appendage located on the abdomen of a Crustacea

Question 5

Pereiopods

Answer 5

Walking appendage located on the thorax of a Crustacea

Question 6

Maxillipeds

Answer 6

Function for feeding. Pass food to the mouth

Question 7

Maxilla - 2 pairs

Answer 7

Holds food, tears it, then passes it onto the mouth

Second pair helps draw water over the gills

Question 8

Mandible

Answer 8

Used to crush and hold food

Question 9

Antennae (second antenna)

Answer 9

Usually longer than the antennules. Tactile and chemoreceptor

Question 10

Antennule (first antenna)

Answer 10

Tactile and chemoreceptor

Question 11

What forms the tail fan of a crustacean?

Answer 11

Uropod and telson (which bears the anus)

Question 12

Carapace

Answer 12

projects backwards from the head and covers all of the thorax and protects the crustacean’s gills

Question 13

Chelicerae

Answer 13

Fangs

Question 14

Pedipalps

Answer 14

Like a finger - used for touch, tasting, and manipulating

Question 15

Pedipalp

Answer 15

Contains pores that have venom

Question 16

Chelicera

Answer 16

Venom glands

Question 17

Pedicel

Answer 17

Distributed weight more efficiently

Question 18

Silk glands

Answer 18

Produces silk fibers for attachment

Question 19

Spinneret

Answer 19

Unique, modified appendage that produces silk

Question 20

Sensillae

Answer 20

An extension of the cuticle for chemo and tactile sensing

Question 21

2 major tagma of a spider

Answer 21

1. Prosoma (cephalothorax)
2. Opisthosoma (abdomen)

Question 22

Book lungs

Answer 22

For gas exchange in spiders

Question 23

Ocullus

Answer 23

keeps track of circadian rhythm and day lengths

Question 24

Spriacles

Answer 24

Gas exchange structures. They breath through these holes

Question 25

Tympanum

Answer 25

vibrates when sound hits it

Question 26

Labrum in insects

Answer 26

Helps hold food in position when feeding

Question 27

Gas exchange in insects

Answer 27

There are no hemolymph intermediates

Question 28

Articular membrane

Answer 28

Thin cuticle for movement

Question 29

Pleurite

Answer 29

Chitinous plates at the side of arthropods

Question 30

Tergite

Answer 30

Dorsal chitinous plate of the arthropod

Question 31

Sternite

Answer 31

Ventral chitinous plate of the arthropod

Question 32

How do chelicerates, hexapods, and crustaceans feed when they have no functional cilia?

Answer 32

Chelicerates - liquid feeders Hexapods - biters and chewers, suckers, piercers, spongers Crustaceans - biters/chewers, piercers/suckers, lickers, suspension feeders

Question 33

Function of the Malpighian tubules and how do they differ in chelicerates and hexapods?

Answer 33

Malpighian tubules are branchy and function as an excretory system In chelicerates, they are endodermally derived In hexapods, they are ectodermally derived

Question 34

Hepatopancreas

Answer 34

Also known as the cecum, it is the liver-pancreas. Excretory system

Question 35

Circulatory system

Answer 35

Open. Has hemolymph consisting of: Hemocyanin - respiratory pigment (copper-based) Cells - amoebocytes: their immune system. Similar to our white blood cells - Explosion cells: injury prevention system; similar to our platelets

Question 36

Pericardium

Answer 36

Bag around the heart. Analagous to our heart chamber

Question 37

How does hemolymph enter and exit the heart and arteries?

Answer 37

The volume inside the heart will make a vacuum by the relaxation of muscles, thereby bringing the hemolymph in

Question 38

Excretory system of crustaceans

Answer 38

Have a modified, closed, metanephridia. They have an end sac, called the peritoneum They have a labyrinth that creates fluid flow to push through and gets rid of water Path: endsac, nephrostome, nephridioduct, bladder, metaphridiopore Excretes water and ammonia

Question 39

Excretory system of hexapods and chelicerates

Answer 39

Malpighian tubules. Gets rid of uric acid (ammonia) as a solid. Spiders and insects don't urinate