Phylum Echinodermata

Classification Of Animals|Phylum - Nematoda|Phylum - Annelida|Arthropoda|Mollusca|Echinodermata

How many from the following phylum has external fertilisation with indirect development ? {Porifera, Ctenophora , Echinodermata, Hemichordata }

The name Echinodermata was coined by

Which is characteristic feature of Echinodermata?

Which of the following is not related with Echinodermata?