Diversity in Living Organisms

External ears (pinna) are present in mammals.

Starfish shows radial symmetry as it can be divided into any plane through its centre.

Obela is a cnidarian and it possesses a canal system.

Ventral nerve chord is present in invertebrates.

The body of Poriferan has many pores, canals and chambers through which water flows. This is called canal system.

Polyps lead solitary or colonial life but are always fixed (sedentary).

Coelenterates are the animals with a diploblastic body plan and are radially symmetrical.

Ascaris belongs to phylum Aschelminthes and it has non-segmented body.

Metridium, an anthozoan cnidarian, contain nematocysts (stinging cells) called cnidoblasts.

Platyhelminthes phylum is characterised by triploblastic organisms with radial symmetry, elongated, dorsoventrally flattened body without segmentation.

Cyclops are crustaceans, which belong to phylum Arthropoda.

Annelides have excretory organs called nephridia. However, no such organ is present in lower organisms.

Phylum Annelida includes the animals, which are triploblastic and contain coelom.

Arthropods have reduced body cavity and filled with blood called haemocoel.

Nematodes are classified under the phylum Aschelminthes.