Sehai and Sidak observed an animal in their garden. Sehai called it an insect while Sidak said it was an earthworm. Choose the character from the following which confirms that it is an insect.

An animal is dorsoventrally flattened,has three embryonic germ layers,and is acoelomate. Which phylum does it belong to? What are they commonly called? Give one example.

Name the phylum to which Leech and Earthworm belong.

To which class of Animalia does the housefly belong? Mention any three characteristic features of this class of animals. Give two other examples of this class of animals.

Classify the following organisms based on the absence/presence of a true coelom (i.e., acoelomate, pseudocoelomate, and coelomate): $Spongilla$, $Sea \text{ } anemone$, $Planaria$, $Liver \text{ } fluke$, $Wuchereria$, $Ascaris$, $Nereis$, $Earthworm$, $Scorpion$, $Birds$, $Fishes$, $Horse$.

Protochordates possess a notochord in larval forms. Appraise the use of this feature in these animals.