What is/are the threat(s) to coral reefs?

Which of the following structures does this organism possess?  

This fin labeled is a ______________________ fin.

Intracellular digestion is ___________________________ and is found in  ___________.

This dogfish shark pup was nourished by a yolk sac, but not a placenta in the mother’s body.  Therefore, this species is  

These organisms are

The structure labeled is part of the

Which of the following characteristics do chondrichthyes (sharks, skates and rays) and osteichthyes (bony fish) share?

This organism is an adult tunicate. How can this organism be classified in the Phylum Chordata, given its relatively simple body plan?

In deuterostomes the blastopore becomes the