Question

Blue coral is
(a)Meandrina
(b)Millepora
(c)Heliopora
(d)Corallium

Answer 1

Hint: Blue coral is a part of the group - colonial coral, which is an octocoral famous for its ability to form large skeletons. The skeleton they form is of aragonite. A narrow layer of tissue is connected with the exterior of the skeleton where Individual polyps exist.

Complete answer:
Blue coral is a Heliopora, which is a part of the monotypic family in the phylum cnidaria. Among the total three species, one species is only known from the fossils.
The massive skeleton of a blue coral is made up of microcrystalline aragonite and calcium carbonate.

Additional Information: -Blue coral is a tolerant species which are grown in marine aquariums where hermatypic zooxanthellae which are blue or grey-grey polyps present within its tubular structure, where each has eight tentacles and their colonies are either similar to columns or branched.
-The unique color skeleton of Heliopora coerulea is due to the presence of iron salts which permits uncomplicated identification in fossil outcrops.
-Due to its attractive color and unique growing pattern, blue corals are widely used in marine aquariums.
So, the correct answer is ‘Heliopora’.

Note: -The IUCN has named blue coals as vulnerable species and provide conservation even though they are found common in certain places. The population of blue corals is still to be learned but it is known to be reducing its amount at a global rate due to aquarium harvesting and destruction of habitat by bleaching, acidification, and global warming.
-Yaeyama Islands (Ishigaki Island) of southwestern Japan is where the largest colony of blue corals known to human beings exist.
-Eastern and western part of the Indian Ocean, random distribution of colonies in several areas of Pacific Ocean along with the coastal regions of Australia and Japan are some other common regions where blue corals are present.