Phylum Arthopoda

Question 1

What are the two main classes of this phylum?

State the orders of class 1  (6)
and classes of class 2 (2)

Answer 1

1. Class Malacostraca
   - Superorder Hoplocarida
   - Superorder Eucarida
   - Order Decapoda
   - Infraorder Brachyura
   - Order Isopoda
   - Order Amphipoda
2. Class Maxilipoda
   - Infraclass Cirripedia
   - Sub-class Copepoda

Question 2

What are the 3 sub-phylums?

Answer 2

1. Hexapoda
2. Crustcea
3. Chelicerata

Question 3

Explain the characteristic differences between Class Malacostraca and Class Maxilipoda.

Answer 3

Class Malacostraca is usually larger, their bodies consist of 19 or 20 segments. They have well-developed hard shell coverings (Carapace) and include a telson and uropods.
Class Maxilipoda are smaller species that all have a reduced abdomen with few or no appendages.

Question 4

What is Phylum Arthropoda characterized by?

Terms involved: 
Exoskeleton 
Chitin
Molt
Dioecious

Answer 4

1. Their chitinous exoskeleton that provides:
   - A hard framework/Structure to their bodies
   - Protection/ armour like
   - Desiccation
   - Exoskeleton limits growth, therefore must be mounted seasonally.
2. Jointed appendages
3. Bigger brains than Annelids
4. Most are Dioecious

Question 5

What are the 3 Orders within Phylum Arthropoda?

Answer 5

1. Amphipoda
2. Isopoda
3. Decapoda (most important)
   > Crabs,
   > Prawns,
   > Shrimps,
   > Crays,
   > Amphipods + Isopods etc..

Question 6

What are the 2 Superorders?

Species involved:
Mantis shrimps
Planktonic filter feeders

Answer 6

1. Eucarida
   > Planktonic filter feeders
2. Hoplocarida
   > Mantis Shrimps

Question 7

What is the 1 infraorder?

Answer 7

Brachyura

> True crabs

Question 8

What is the 1 infraclass?

Answer 8

Cirripedia

Question 9

Name/list the species with Pereopods and what each sp uses them for.

Answer 9

1. Planktonic filter feeders (Eucarida)
   - Use their pereopods to filter food from the water as they swim.
2. Mantis shrimps (Hoplocarida)
   - Use their pereopods for hunting
3. True crabs (Brachyura)
   - Four other pereopods used for walking
4. Amphipods have 7 pairs of highly modified pereopods used for different tasks.
5. Decapods have pereopods

Question 10

Class Malacostraca: Reproduction

Terms involved:
Pleopods
Brood
Zoea larva

Answer 10

• Most male decapods have anterior pleopods adapted as copulatory organs
• Most female decapods brood their eggs attached to pleopods
• The zoea larva is the typical hatching stage
  1. Nauplius
  2. Zoea
  3. Post-larval

Question 11

Long bodied forms:

Answer 11

1. Shrimps
2. Lobsters
3. Crayfish
   All have well-developed abdomens

Question 12

Order Isopoda body form

Answer 12

Their bodies are dorsoventrally flattened.

Question 13

Cirripedia (Barnacles)

Answer 13

> Calcareous (Calcium carbonate) shell called Carina, composed of 5 or more plates.
Operculum:
- Two moveable plates, Scutum and Tergum closed during low tide.