Question

Which of the following is an example of Ctenophora ?
A. Beroe and Cestum
B. Ctenoplana
C. Pleurobrachia
D. All of the above

Answer 1

Hint: In order for you to arrive at the correct answer, you must first understand that animals are divided into different phylums based on certain external and internal characteristics. One such phyla is the phylum Ctenophora that mainly resides in the marine waters.

Complete answer:
 The animal kingdom is divided into different phyla as mentioned above. They are namely:
1. Porifera-This phylum mainly consists of sponges both freshwater and marine waters.
2. Coelenterata (Cnidaria)-They are also known as the ctenophora and consist of acoelomate animals which are radially symmetrical. They have a single opening called the hypostome. Some examples are Beroe, Cestum, Ctenoplana and Pleurobrachia.
3. Platyhelminthes-They consist of the flatworms with unsegmented , bilateral and flat bodies.
4. Nematoda-They are bilaterally symmetrical and triploblastic animals and are also known as the roundworms. They are found in a wide variety of environments.
5. Annelida-They are also known as ringed worms or segmented worms. They are found worldwide.
6. Arthropoda- Arthopoda typically means jointed foot. They consist of a chitinous exoskeleton. They have jointed and paired appendages.
7. Mollusca-They are the second largest phyla after arthropoda.They are soft bodied and have a hard exoskeleton made of calcium carbonate.
8. Echinodermata-They are spiny skinned and are exclusively marine.
9. Hemichordata-They are also called the sister group of echinodermata. They are marine.
10.Chordata-They are characterized by the presence of a notochord, a dorsal nerve cord, pharyngeal slits, and a post-anal tail. The notochord is present at some point of the life cycle of the organism.

Moreover,let us now look at each of the options mentioned above.
1)Beroe and Cestum-Beroe are a species of comb jelly of the family Boidae. They belong to the phylum Ctenophora. On the other hand, Cestum is also a species of comb jelly belonging to the family Cestidae of phylum Ctenophora. They are also known as the Venus Girdle.
2)Ctenoplana-They are the only genus of comb jellies found in the family Ctenoplana. They also belong to the phylum Ctenophora.
3)Pleurobrachia-They are also known as sea gooseberries and exhibit the phenomenon of bioluminescence. They also belong to the phylum Ctenophora.
Each of the organisms mentioned above belongs to the phylum Ctenophora.

So, the correct answer is option D All of the above.

Note:
Although there are many different phyla, we most closely know the phylum chordata as it contains humans and other chordate animals. The most striking feature is the notochord which is present throughout the life of some animals or it may be present at a particular stage during development.