The Sea Anemone

By: Leah Walsh Block 2

The Integumentary System

Sea anemones are found and known for their various sizes and vibrant colors. They can range from 1/2 inch to 6 feet depending on the environmental conditions it lives in. All anemones are brightly colored to attract prey to them until they use their multiple tentacles to inject a poison into their prey and paralyzing it. The tentacles (usually 10) will surround a central foot that is adhesive and sticks to the ground where sea anemones are located.
  • Like coral, sea anemones will create bonds with animals like the famously known clownfish. (Nemo!) The anemone offers protection for the clownfish who is immune to the tentacles' sting.

Skeletal and Muscular System

The sea anemone has a hydrostatic skeleton which means they do not have any solid bones but instead they have fluid filled compartments that are kept under pressure. Although they do not act as support for the sea anemone, it helps it keep its shape under water. These compartments are surrounded by an outer muscle the extends through the animal's entire body. In addition they also have circular muscles at the center of the body. Movement happens when either one of the muscles contracts or expands changing the pressure in the fluid compartments. This also allows them to change their shape more freely.
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Nervous System

The sea anemone has one of the simplest types of nervous systems in animals. They do not have a brain or eyes and signals are sent and received along a structure called a nerve net. The nerve cells communicate through a process called en passant synapse where the signals are transferred only when the cells pass each other along the nerve net. These signals will interact and control the sensory and contractile cells for the sea anemone's movements and reactions.
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The Respiratory System

Being a simple animal, the sea anemone does not have a respiratory system or respiratory organs. Their form of respiration is diffusion through their inner and external body covering. Water is essential for respiration and they use the oxygen from the water and expel carbon dioxide.

Circulatory System

In an anemone, the respiratory system and the circulatory system are very similar and use the same functions. The sea anemone does not have a true circulatory system so the intake of water, materials, and nutrients happens through diffusion in their outer covering. Some intake also occurs in through their mouth which is in the center top of the animals. To aid in the circulation of these materials, the sea anemone's symbiotic animals, like the clown fish, stir up the water around the animal allowing for a variety of nutrients in the water to make its way to the anemone.
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Excretory and Digestive Systems

The sea anemone is a carnivorous animals, eating usually plankton and small fish. The anemone has one main opening on its body and its in the center called its mouth. The mouth is surrounded by the tentacles lined with nematocysts giving them their stinging power. As the anemone's prey passes by, the tentacles will grasp the prey and subdue it, pushing it into the mouth. From the mouth, the food travels into the anemone's gut and digestive mucus will break down the food. Any materials that are not broken down are released back through the mouth opening.

Reproductive System

Sea anemones can reproduce both asexually or sexually.

  • Asexual reproduction can occur in multiple ways but the most common process is through budding. This is when the new anemone is formed by a protruding in the parent and then breaks off. Another way asexual reproduction happens is when the anemone will divide itself longitudinally. No matter what, the resulting anemone from this type of reproduction is completely identical in DNA to the parent.
  • Anemones may also reproduce by sexual reproduction. Some are hermaphroditic where they produce both egg and sperm while others are strictly one gender. The egg and the sperm are released through their mouths. Once an egg and a sperm meet in the water an anemone begins to form. At this stage they are called planula and they will float to the ground and grow with a different DNA.
It is thought that the anemones in shallow water will reproduce asexually while those in deep water will reproduce sexually.

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Works Cited

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