Question

name the key feature of the body cavities of the following and mention which animals have a true cavity
a) sponges
b) cnadarians
c) annelids

Answer 1

a) Sponges - have a water canal system. Water enters through minute pores called ostia in the body wall into a central cavity, spongocoel, from where it goes out through the osculum.

b) Cnidaria - The have a central gastro-vascular cavity with a single opening called hypostome.

c) Annelida - They are animals with true coelom.