Coelom is absent in

$A.$ Animals are multicellular organisms composed of eukaryotic cells.
$R.$ Sponges do not perform photosynthesis and obtain nutrition by absorption.

Select the correct option for the labeled part $X$ and $Y$ from the given diagram.

The term "phylum" in animal classification was coined by

Give one example each for an animal possessing placoid scales and that with cycloid scales.

Which of the following is not a subspecies of tiger?