स्पंज (पोरिफेरा) में जटिल नाल तंत्र (कैनाल सिस्टम) मुख्य रूप से किसके कारण विकसित होता है?

The post-anal tail is a distinctive feature of chordates, which is universally present during which phase?

Which of the following combinations of lungfish genus and its native geographical region is correct?

Hagfish and lampreys are classic examples of which group of organisms?