A lesson on the biology of sea jellies. The reading is accompanied by true/false questions.
• To introduce students to the biology of sea jellies.
Sea jelly is the name used by marine biologists to refer to the animals known to the general population as jellyfish. Students who have learned their lessons well should also refer to these beautiful and interesting sea creatures as sea jellies because they are not fish at all. Sea jellies belong to the scientific phylum Cnidaria which also includes coral, hydras and sea anemones. These other members of the phylum Cnidaria attach themselves to rocks or coral while sea jellies are moving animals. Some species of sea jellies are active swimmers while other species rely on winds and currents to move them through the ocean waters.
One characteristic of the sea jellies and other members of their phylum is radial symmetry. This means that the body parts of members of the Cnidaria phylum are distributed around a central axis or center line. Humans and other mammals have a body that is balanced on two sides of a center line; this is bilateral symmetry.