Figure 11.9: The Portuguese man-o-war can deliver debilitating stings with its tentacles.
( 13 )
Coral reefs are built from colonial cnidarians called corals (Figure11.10). The corals are
sessile polyps that can extend their tentacles to feed on ocean creatures that pass by. Their
skeletons are made up of calcium carbonate, which is also known as limestone. Over long
periods of time, their skeletons can accumulate to produce massive structures known as coral
reefs. Coral reefs are important habitats for diverse types of ocean life.
Figure 11.10: Corals are colonial cnidarians. ( 4 )