MediumBiologyHigh School (11–12)Diversity of Living Organisms › Basis of Animal ClassificationNumerical
A sample from a pond edge holds 6 Hydra, 9 flatworms, 27 roundworms and 8 earthworms.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A sample from a pond edge holds Hydra, flatworms, roundworms and earthworms.
- How many animals are in the sample?
- How many of them are triploblastic?
- What per cent of the sample are true coelomates?
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. Total. animals.
Step 2. Triploblastic. All but Hydra: .
Step 3. Coelomates. Only the earthworms: .
Answer: ; ; .
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