Topic 15: Ecdysozoa Flashcards
T/F
Ecdysozoans are the least species-rich group
false
they’re the MOST species rich group!
Protostomes are ____mono/para/ polyphyletic with __ major lineages
monophyletic
2
Explain the difference in the way lophotrochozoans and Ecdysozoans grow
- Ecdysozoans grow by molting: short-term burst of growth
- lophotrochozoans grow incrementally: continuous growth- add layer outwards forming growth bands
Define ecdysis (and cuticle)
the process of molting the cuticle in order to grow
- cuticle= non-living outer layer of skin to protect from the environment
- entire cuticle is shed at once
Particular regions of the cuticle are __(hardened). The cuticle in between is ____-(flexible, allows for movement)
-hardened regions are called ___ when shaped like plates
sclerotized
unsclerotized
- sclerites
Cuticle is often strengthened by ___
chitin
below the cuticle is the _____ which: ________
epidermis
living cells that secrete substances to the cuticle
*note: very fine ducts run from epidermis to top of cuticle
3 layers of the cuticle are:
- endocuticle: (endo=within)
- Exocuticle (exo=outside)
- Epicuticle (epi=upon)
Explain the 6 steps of the molting process
- intermolt stage
- apolysis: separation of epidermis from cuticle
- secretion of fluid & growth of epidermis
- secretion of new cuticle
- activating of enzymes in molting fluid
- shedding of old cuticle
nematodes include __ and ___
roundworms and threadworms
Ecdysozoans include _____ and _____
nematodes
arthropods
what 4 things are morphologically similar in all nematodes?
- no segmentation
- no appendages
- no eyes
- slightly blunt at one end, slightly pointy at the other
describe the coelom in nematodes
they’re pseudocoelomates
body cavity, not completely lined by mesoderm
nematodes use ___(in/external fertilization) and some are ____(1 individual has both male and female organs)
internal
hermaphrodites
Nematodes grow (post-embryonic) by each cell growing, not by the addition of cells what is this called?
Eutelic
