The picture below shoes the limbs of four different species. The four species illustrated most likely have similar limb structures because they all adapted to the same environmental conditions
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use their limbs for the same function
occupy the same level of the food pyramid
share a common ancestor

Share a Common Ancestor

Explanation

Animals that evolved from a common ancestor will always share similar structures. This can be seen when comparing the hand and arm structures of humans, dogs, and chimps.

organisms that lack symmetry are called asymmetrical and belong to phylum porifera/sponges.

organisms with specialized stinging cells belong to phylum cnidaria. stinging cells are called cnidoblast cells.

cnidarians show two morphological forms : polyp (sessile) and medusa (mobile)

filter feeding is observed in porifera members.  

alternation of generation is observed in coelenterata or cnidaria. there is alternation of asexual polyp form and sexual medusoid form. it is also referred as metagenesis.

✿   this landform has a high elevation and a high relief

✿   this landform is a mountain