Give examples for the following.
(a) Bilateral, dorsiventral symmetry is found in ____.
(b) Worm causing disease elephantiasis is ____.
(c) Open circulatory system is found in ____ where coelomic cavity is filled with blood.
(d) ____ are known to have pseudocoelom.

Correct Answers:

(a) Bilateral, dorsiventral symmetry is found in Liver fluke (Fasciola hepatica).

(b) Worm causing disease elephantiasis is the Filarial worm (Wuchereria bancrofti).

(c) Open circulatory system is found in arthropods where the coelomic cavity is filled with blood.

(d) Nematodes are known to have pseudocoelom.

Explanation:

Filaria is a protozoan, parasitic in nature. Elephantiasis is caused by Wuchereria.

In Arthropoda, the coelom is filled with blood.

The true coelom means a body cavity that arises as a cavity in the embryonic mesoderm.

In arthropods, annelids, and Mollusca, true coelom develops by splitting up of mesoderm, while in the cavity of Arthropoda and non-Cephalopoda molluscs colorless blood is present and is called hemocoel.
In echinoderms and chordates, the mesoderm layer arises from the wall of the embryonic gut or enteron as empty outgrowths or enterocoelomic pouches.
In coelenterates body cavity or coelomic cavity is absent.