Question 1

Why is Arthropoda called the largest animal phylum?

Accepted Answer

Arthropoda has an enormous diversity of species and includes insects, crustaceans, arachnids and several other groups. Its success is linked to features such as a protective exoskeleton, segmented body and jointed appendages.

Question 2

What are tagmata in arthropods?

Accepted Answer

Tagmata are functional groups formed by grouping the segmented body of an arthropod. In the Palaemon example, the visible groups are the cephalothorax and abdomen, although the exact arrangement differs among arthropod groups.

Question 3

Why do arthropods need to moult?

Accepted Answer

The chitinous exoskeleton is rigid and does not expand continuously with the body. Arthropods therefore shed the old cuticle by ecdysis, expand, and then the new cuticle hardens.

Question 4

Which respiratory organs are found in arthropods?

Accepted Answer

Arthropods do not all use the same respiratory organ. Different groups may use gills, tracheae or book lungs; the Palaemon model specifically shows crustacean gills attached near the bases of the walking legs.

Question 5

What are green glands in Palaemon?

Accepted Answer

Green glands are the excretory organs of Palaemon and are located in the head region. In this model they are shown as paired teal organs, while the gills are shown separately near the walking-leg bases.

Arthropoda Lab — Palaemon Prawn: Tagmata, Jointed Limbs & Moulting

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