EasyBiologyHigh School (11–12)Diversity of Living Organisms › Basis of Animal ClassificationConceptual
Neha compares a section of Hydra with a section of a liver fluke.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Neha compares a section of Hydra with a section of a liver fluke.
- In Hydra, she sees an outer cell layer, an inner cell layer and a jelly between them. Is Hydra diploblastic or triploblastic?
- The fluke has a third layer of cells between the outer and inner layers. What is it called?
- Does the fluke have a body cavity?
Need a reminder? The key ideaShow
Diploblastic animals have ectoderm and endoderm with mesoglea between (coelenterates). Triploblastic animals add mesoderm. A coelom is a cavity lined by mesoderm (annelids to chordates). In a pseudocoelom the mesoderm is in scattered pouches (Aschelminthes). Acoelomates have no body cavity (Platyhelminthes).
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) Two cell layers with mesoglea between: diploblastic.
Step 2. (b) The third cell layer is the mesoderm, so the fluke is triploblastic.
Step 3. (c) No. Flatworms are acoelomates; mesoderm cells fill the space.
Answer: (a) diploblastic; (b) mesoderm; (c) no body cavity.
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