Cnidarians:
These aquatic animals come in a bewildering variety of forms and
include jellyfish, sea anemones, corals, sea pens, sea fans, sea
daisies, hyrdoids and hydras. What looks like a single individual is
often a colony of polyps with specialised functions. In Porpita (example
shown here) there are polyps for providing buoyancy, feeding (in the
form of tentacles), digestion and reproduction
