Question

Absence of excretory organs,great power of regeneration and exclusively marine animals,belong to the phylum
A) Mollusca
B) Arthropoda
C) Echinodermata
D) Annelida

Answer 1

Hint:Phylum is a taxonomic rating that falls third in the hierarchy of classification, after domain and kingdom. Organisms in a phylum share a collection of characteristics that distinguishes them from organisms in another phylum. Throughout scientific history, the characteristics that group animals into a phylum have changed, as better methods have evolved to decide how groups of animals are related.

Complete Answer:
>Echinoderms are a wide group of marine animals only (scientific name Echinodermata). The name comes from the word for "spiny skin" in Greek.
>Such species are a marine phylum that can be found at any depth of the ocean and have no members living in freshwater environments. The species of this phylum consists of sea urchins, sea cucumbers, and starfish and are fairly well known.
>Echinoderms do not have primary excretion organs, but instead expel their nitrogenous waste through their respiratory system in the form of ammonia.
>However, the anus is present in most echinoderms and is often used to jettison waste. However, the main way the respiratory system works is mainly by the exchange of gases and liquids. This is one example of the many functions provided by an organism's system.
>Near the centre of echinoderms, podocytes, cells specialised for ultrafiltration of body fluids, are present. These podocytes are bound to an opening called the madreporite by an internal system of canals.

Thus the correct answer is option (C) Echinodermata.

Note:From the intertidal zone to the ocean depths, there are about 7,000 species normally found on the sea floor in any marine habitat. They've got a wide range of colours. On the Great Barrier Reef, there are at least 800 echinoderm species.