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Cnidarians. Kiara Cruz Rodriguez, Foster Reynolds, Maddi Kornegay, & Mason Murphy . What are Cnidarians?. Cnidaria – a phylum of aquatic invertebrate animals that comprises (makes up) the coelenterates
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Cnidarians. Kiara Cruz Rodriguez, Foster Reynolds, Maddi Kornegay, & Mason Murphy
What are Cnidarians? • Cnidaria – a phylum of aquatic invertebrate animals that comprises (makes up) the coelenterates • Cnidarians are stinging animals. They have two basic tissue layers. They’re more complex than sponges. They have no front or back because they have radial symmetry, and they have two life stages. They are very complex organisms, and they have no backbone.
Life Stages • Polyps – In this stage, cnidarians are sessile, or attached, to rocks and/or Corals. Since these cnidarians are sessile and not free floating they reproduce asexually. Some examples include Coral, anemones, etc. • Medusa – This is the later stage in cnidarian life. They are free floating. They are not attached or anchored to anything. They swim around freely in the ocean. They have tentacles at the bottom of their bell shaped bodies to help them move around. These cnidarians reproduce sexually. These brain corals are examples of Polyps Jellyfish are an example of medusa life forms
How It Eats • Cnidarians eat and expel waste just like us. The only difference is that they eat and expel through the same opening/cavity. • They eat by drawing in prey using their tentacles. Their tentacles, of course, have stinging cells, which stun their prey long enough for them to eat it. • They digest their food in the body cavity, and after it has been digested the waste comes out of their mouth/anus.
Other Info Stinging Cells Fun Facts Some animals, like clown fish, are immune to the sting of cnidarians Most cnidarian’s nematocysts are not harmful to humans, as the stinger cannot penetrate sufficiently into human skin to cause any harm. There are some jellyfish which can deliver extremely painful, and in a few cases, even fatal, stings to humans. These include the Portuguese man of war, and the box jellyfish. • Cnidarians have stinging cells called cnidocytes and contain a structure called a nematocyst. These stinging cells are used to capture and subdue prey. • The nematocyst is a coiled thread-like stinger. When the nematocyst is called upon to fire, the thread is uncoiled, and springs straight. The thread punctures through the cnidocyte wall and into the prey.
Cool Cnidarians • Jellyfish • Sea Pens • Coral • Sea Anemones • Portuguese Man o’ War • Hydras
Resources • http://www.brainpop.com/science/diversityoflife/cnidarians/ • http://www.biology4kids.com/files/invert_jellyfish2.html • http://www.biology4kids.com/files/invert_jellyfish.html