Question

'Tornaria' is the larva of
1. Starfish
2. Balanoglossus
3. Cuttle fish
4. Holothuria

Answer 1

Correct Answer - Option 2 : Balanoglossus

Concept-

• The larva is a stage in the development of many animals, occurring after birth or hatching and before the adult form is reached. These immature, active forms are structurally different from the adults and are adapted to a different environment.
• There are different types of larvas like Tonaria larva, Muller's larva, Tadpole larva, etc.

Explanation-

• Balanoglossus belongs to the phylum Hemichordata.
• Animals of this phylum are worm-like, brittle, and soft.
• The body is divided into three-part:
  • Proboscis
  • collar
  • trunk
• The true notochord is absent, a notochord like structure is found in their buccal cavity called "Buccal diverticulum" or "Stomochord" 
• Development is indirect.
• The animals have tornaria larva (planktonic larva)  just like bipinnaria larva of Echinodermata in their developmental stages.

Thereby 'Tornaria' is the larva of Balanoglossus.

• Starfish larva is Bipinnaria/Dipleura.
• Holothuria is a sea cucumber and larva is Auricularia.
• Cuttlefish is sepia and larva is absent.