and circulatory functions. The cnidarians also have nerve tissue organized into a net-like
structure. Cnidarians do not have true organs, however.
Figure 11.6: Jellyfish have bell-shaped bodies with tenticles. ( 8 )Cnidarian Colonies
Some types of cnidarians are also known to form colonies. For example, the Portuguese
man-of-war looks like a single organism but is actually a colony of polyps (Figure11.9).
One polyp is filled with air to help the colony float, while several feeding polyps hang below
with tentacles full of nematocysts. Consequently, the Portuguese man-of-war is known to
cause extremely painful stings to swimmers and surfers who accidentally brush up against
these creatures in the water.