Although considered somewhat simple creatures compared to other animals, sea anemones are among the more complex invertebrates. Sea anemones have some key characteristics that are not seen in any other organisms except the Phylum Cnidaria, such as Nematcysts. Nematocysts are the characteristic feature of anemones. The nematocysts that are found in the tentacles and the oral disc of anemones are called the spirocysts. The nematocysts of any anemone are stinging mechanisms used for defense against predators. The nematocysts of an anemone are just the beginnings of how intricate these animals are. The figure below shows some of the various internal and external parts of an anemone.
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The Column of the anemone is the organism's body wall. It is supported by internal water pressure in certain cavities. For this reason, their skeleton is described as a Hydrostatic skeleton. An anemone's Pedal Disc is used primarily for attachment to various substrates. The pedal disc is located on the posterior side of the animal, and serves as a type of holdfast to substrates. It also serves as a means of locomotion. This pedal disc movement from one substrate to the next is the cause of pedal laceration as well. The long, flowing Tentacles are found on the Oral Surface of the animal. These tentacles typicality |
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eight to several hundred per individual, and are used for feeding.
The Siphonoglyph,
is also found at center of oral disc. This opening that allows water
to enter into the gastrovascular cavity by way of cilia. This water
helps maintain the hydrostatic skeleton.
The Pharynx of an anemone is found directly behind the opening of the mouth of this creature. It is in the anterior of the gut, and is used in the same manner as humans use their esophagus. This muscular tissue is closed by water pressure in the gastrovascular cavity . The Acontia are thread-like pieces of the body that are found near the pedal disc of the animal. They are attached to the Septal Filaments inside of the body, and at times they will flow into and out of the gastrovascular cavity of the organism. As mentioned in previous pages, the Gonads of anemones are found in the gastrovascular cavity. Although these animals are hermaphroditic, they will produce only one gamete type(either eggs or sperm) at a time in order to breed with other anemones. Anemones are more complex than some animals, yet they still tend to be somewhat simple organisms in that they have no circulatory, excretory, or respiratory systems. Their septa increase their surface area for digestion, which occurs both extracellularly and intracellularly. The Mesentaries are the tissues layers dividing the body cavities of these animals. |
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Copyright 2002 Karlee Markovich