lecture 5

Question 1

evolution of exoskeleton

Answer 1

clade= ecdysozoa
tough cuticle or shell
-stair case growth
-periodic moulting (shedding)

Question 2

phylum nematoda

Answer 2

clade that contains round worms
pseudoccelamate (hemoceol) body structure- partially filled

body covered w/ cuticle, sheds it to grow.

not segmented and is flexible

most common animal on earth

Question 3

Arthropods and their characteristics

Answer 3

Phylum in this group are found in nearly all habitats (insects)

Body plan: segmented, hard exoskeleton, jointed appendages

Tagmata: segments grouped together

Well developed sensory organs, arthropods molt (energetically expensive)

Open circulatory system: no veins- pumps back in, hemoceol is main cavity. hemolymph is circulated

Question 4

Appendages evolution

Answer 4

arthropoda Phylum

Exoskeleton w/ joint appendages= for walking

Defence (the claws)
Fangs (injects venom)
Sensation (antennae)

Question 5

Arthropod clade chelicerata

Answer 5

Arachnids= spiders, ticks, mites
Open circulatory system

Have abdomen and cephalothorax
(2 tagmata)

Posterior tagmata= heart, book lungs, silk and poison glands, etc.

Book lungs= folds to increase sa

6 appendages (8 legs total)

Question 6

Arthropod clade myriapoda

Answer 6

Means many legs
Centipedes (leg/segment, carnivorous)

Millipedes: 2 pairs leg/segment, herbivorous

Question 7

Arthropod clade pancrustacea

Answer 7

Terrestrial insects are more closely related to this than myriapods

And some crustaceans are more related to myriapod than other crustaceans

Paraphyletic

2 segment groupings (tagmata)
→ cephalothorax…
-2 pairs of antennae, 3+ modified mouth parts, chelipeds (claus), walking legs, appendages on tail region (is heavily muscled

Swimming larval phase

Question 8

Carcinisation

Answer 8

Everything evolves into crab

Question 9

Evolution of flight

Answer 9

Occurs in hexapoda clade (6 leg)

Insect wing are extensions of exoskeleton and cuticle

No appendages (unlike birds- sacrificing)

Success: predetors, dispense to new habitats quickly

Question 10

Arthropod clade hexapoda (huge clade- insects)

Answer 10

light weight chitinous exoskeleton

3 tagmata: head=4 segments,
Thorax = 3 seg,
abdomen = up to /11

• Malpighian tubules - waste removal)
• Tracheal tubes - tracheal gas exchange through
  Pores

Undergo metamorphosis

Question 11

2 types of metamorph

Answer 11

Iranstormation from larva to adult
- campere metamorphosis
Ex: maggot, grub, caterpillar - to adult (butterfly)

incomplete metamorphosis
- younger nymphs resemble adults (smaller Shrimp to adult)
- true bugs, grass hoppers
Ex: instars → just becomes bigger larva (eat diff not just turns big)