Question

Which among the following belong to the same phyla?
A. Physalia, obelia, Pleurobrachia -Coelenterata
B. Bombyx, Palaemon, Limulus - Arthropoda
C. Starfish, jellyfish, Sea urchin - Echinodermata
D. Cuttlefish, devil fish, Patella – Mollusca

Answer 1

Hint: The organisms are classified on different basis , one such way is to characterize organisms on the basis of their body plan. The basic body plan includes the classification on the basis of the level of organization, body symmetry, body cavity and much more.

Step by step answer:First the organisms are classified on the basis of the level of organization means the cellular level is exhibited by poriferans, tissue level is exhibited by coelenterates and ctenophore, organ level is exhibited by Platyhelminthes and aschelminthes and organ system is exhibited by Annelida to hemichordate.
Physalia, obelia, Pleurobrachia -Coelenterata:- The animals of this phylum are called cnidarians. They possess an aquatic habitat as they inhabit the water bodies. Like sponges, they are also mostly marine but few are freshwater inhabitants also (e.g., Hydra). other examples are Physalia and Obelia but Bombyx, Palaemon, Limulus – Arthropoda:- It is the largest phylum of the animal kingdom with about 9,00,000 species. This phylum is a much heterogeneous group including a variety of animals differing in structure, habitat, feeding habits and other characteristics. All three of them are present in this
Star fish, jellyfish, Sea urchin – Echinodermata:- Echinodermata literally means "spiny or prickly skinned" (Greek, echinos-spiny, derma- skin). They possess an endoskeleton (internal skeleton) of calcareous ossicles (small bones), embedded in the skin. jelly fishes belong to the kingdom coelenterates.
Cuttlefish, devil fish, Patella – Mollusca :- they are characterized by having a soft body. They are usually found in all habitats. Cuttle fish and devil fish belong to this but the patella is a kind of joint present in the knee.
Hence option B is correct.

Note: The body of arthropods are covered by a hard, water-proof exoskeleton made up of chitin. This chitinous exoskeleton is one of the reasons for the successful existence of arthropods on the earth. It provides protection and support to the body and the internal organs present inside the body. Moreover, it also prevents the loss of water due to evaporation thus enabling the arthropods to live in relatively dry environments.