Arthropods: A segmented success story

Question 1

What are tagmata?

Answer 1

Specialized groupings of multiple segments into a functional morphological unit

Question 2

What is an example of where segments within tagmata fuse completely?

Answer 2

Head

Question 3

What are the 3 tagmata that arthropods typically have?

Answer 3

Head, thorax and abdomen

Question 4

What does the subphylum Chelicerata include?

Answer 4

Horseshoe crabs, scorpions, spiders, mites and ticks

Question 5

What order are Horseshoe crabs?

Answer 5

Xiphosura

Question 6

What are the distinctive features of Xiphosura (horseshoe crabs)?

Answer 6

Prosoma covered by a single carapace, dorsal compound eyes. Opisthosoma (abdomen) composed of fused segments, bears gills and telson. Pedipalps act as extra pair of walking legs.

Question 7

What are included in the class Aracnidae?

Answer 7

Spiders and scorpions

Question 8

What order are spiders?

Answer 8

Araneae

Question 9

What are the distinctive features of order Araneae (spiders)?

Answer 9

Chelicerae modified into fangs, connected to a venom gland
Uses silk produced by silk glands for a range of tasks throughout life (in most arthropods only the larval stages can produce silk)
Some spiders have excellent vision (by far best of all arthropods) and some show learning abilities to capture novel prey types

Question 10

What are included in the subclass Acari?

Answer 10

Ticks and mites

Question 11

What are the distinctive features of Acari (ticks and mites)?

Answer 11

Small, many species ectoparasites but exploit virtually any type of food source and habitat.
Have impacts on health and economics for humans.
Body almost without visible segmentation, mouth parts very varied.

Question 12

What are the distinctive features of order Scorpiones?

Answer 12

Grasping pedipalps and tail with a venomous stinger.
Unique pair of sensory organs known as pectines, located on underside. Sense the texture of the surface and smell pheromones released by other scorpions.

Question 13

What are the 4 well-defined classes of subphylum Myriapoda?

Answer 13

Chilopoda, diplopoda, pauropoda, symphyla

Question 14

What are in the class Chilopoda?

Answer 14

Centipedes

Question 15

What are in the class Diplopoda?

Answer 15

Millipedes

Question 16

What are in the class Pauropoda?

Answer 16

Pauropods

Question 17

What are in the class Symphyla?

Answer 17

Garden centipedes

Question 18

What are the distinctive features of class Chilopoda (centipedes)?

Answer 18

• Predators with venomous forcipules: claws formed by modification of the first pair of legs
• Always uneven number of segments. One pair of legs per segment.
• Length form a few mm to about 30cm.

Question 19

What are the distinctive features of class Diplopoda (millipedes)?

Answer 19

• Generally more slow-moving detritus feeders
• Each segment has two pairs of legs
• Possibly first animals to move up on land about 428mya

Question 20

What animals are in the subphylum Hexapoda?

Answer 20

Very large group of insects - the most diverse group of animals on Earth