Question

The members of chordates exhibit similarity in all the following features except

• A. symmetry
• B. circulatory system
• C. dorsal nerve cord
• D. mode of embryonic development

Answer 1

The correct option is D mode of embryonic development

Chordates differ from each other in the mode of embryonic development. Vertebrates are classified as oviparous, viviparous and ovoviviparous based on the mode of embryonic development. Oviparous animals lay eggs and the embryonic development is outside the body of the mother. Examples: Amphibians, most fish, most reptiles, birds.

Viviparous animals give birth to young ones and the embryonic development is inside the body of the mother. Examples: Mammals like cats, dogs, humans, elephants, lions, tigers.

Ovoviviparous animals produce eggs, but, eggs hatch and develop (in some cases) inside the body of the parent. Examples: Organisms belonging to the class Chondrichthyes like shark and organisms belonging to the class Osteichthyes like the seahorse (Hippocampus).

All chordates are bilaterally symmetrical and have a closed circulatory system. The nerve cord is found on the dorsal side.