Question

The given flow chart represents the classification of animals on the basis of body organisation and coelom. Select the option that correctly identifies the organisms a, b, c and d.

• A. $\begin{array}{cccc}\text{a}& \text{b}& \text{c}& \text{d}\\ \text{Hydra}& \text{Ascaris}& \text{Taenia}& \text{Pheretima}\end{array}$
• B. $\begin{array}{cccc}\text{a}& \text{b}& \text{c}& \text{d}\\ \text{Spongilla}& \text{Planria}& \text{Rhabditis}& \text{Nereis}\end{array}$
• C. $\begin{array}{cccc}\text{a}& \text{b}& \text{c}& \text{d}\\ \text{Euplectella}& \text{Ascaris}& \text{Planaria}& \text{Culex}\end{array}$
• D. $\begin{array}{cccc}\text{a}& \text{b}& \text{c}& \text{d}\\ \text{Hydra}& \text{Fasciola}& \text{Culex}& \text{Planaria}\end{array}$

Answer 1

The correct option is B $\begin{array}{cccc}\text{a}& \text{b}& \text{c}& \text{d}\\ \text{Spongilla}& \text{Planria}& \text{Rhabditis}& \text{Nereis}\end{array}$

Spongilla belongs to phylum Porifera that have cellular level of organisation. Their body is composed of multiple cells that are not organised into any tissue. Thus, ‘a’ is Spongilla.


Planaria belongs to phylum Platyhelminthes that do not have coelom in their body, thus known as Acoelomates. Thus, ‘b’ is Planaria.

Rhabditis belongs to phylum Aschelminthes that have pseudocoelom in their body, thus known as Pseudocoelomates. Thus ‘c’ is Rhabditis.

Nereis belongs to the phylum Annelida that possess true coelom in their body, thus known as Coelomates. Thus, ‘d’ is Nereis.