Sea anemones are flower-like marine invertebrates of the order Actinaria . Named after a terrestrial flower, the anemone, these aquatic animals are classified with the corals in the Class Anthozoa, which means ‘flower animals’. They range in size from less than 1,25 centimeters to nearly two meters in diameter. A sea anemone is basically the typical polyp: a small sac, attached to the bottom by an adhesive foot, with a column shaped body ending in an oral disc. The mouth is in the middle of the oral disc, surrounded by tentacles. Anemones have a range of ten tentacles to hundreds. The tentacles are armed with many cnidocytes, which are unique cells that function as a defense and as a means to capture prey. Cnidocytes contain cnidae, capsule-like organelles capable of everything. The cnidae that sting are called nematocysts . Each nematocyst contains a small vesicle filled with toxins—actinoporins—an inner filament and an external sensory hair. When the hair is touched, it mechanically triggers the cell explosion that fires a harpoon-like structure. This structure attaches to organisms that trigger it, and injects a dose of poison in the flesh of the aggressor or prey. This gives the anemone its characteristic sticky feeling. The internal anatomy of anemones is very simple. There is a gastrovascular cavity, which functions as a stomach. This cavity has with a single opening to the outside, which functions as both a mouth and an anus. (Adapted from: www.newworldencyclopedia.org. Accessed on February 18, 2020) According to the passage, an anemone injects its venom to its enemies using its...

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Sea anemones are flower-like marine invertebrates of the order Actinaria. Named after a terrestrial flower, the anemone, these aquatic animals are classified with the corals in the Class Anthozoa, which means ‘flower animals’. They range in size from less than 1,25 centimeters to nearly two meters in diameter.

A sea anemone is basically the typical polyp: a small sac, attached to the bottom by an adhesive foot, with a column shaped body ending in an oral disc. The mouth is in the middle of the oral disc, surrounded by tentacles. Anemones have a range of ten tentacles to hundreds.

The tentacles are armed with many cnidocytes, which are unique cells that function as a defense and as a means to capture prey. Cnidocytes contain cnidae, capsule-like organelles capable of everything. The cnidae that sting are called nematocysts. Each nematocyst contains a small vesicle filled with toxins—actinoporins—an inner filament and an external sensory hair. When the hair is touched, it mechanically triggers the cell explosion that fires a harpoon-like structure. This structure attaches to organisms that trigger it, and injects a dose of poison in the flesh of the aggressor or prey. This gives the anemone its characteristic sticky feeling.

The internal anatomy of anemones is very simple. There is a gastrovascular cavity, which functions as a stomach. This cavity has with a single opening to the outside, which functions as both a mouth and an anus.

(Adapted from: www.newworldencyclopedia.org. Accessed on February 18, 2020)

According to the passage, an anemone injects its venom to its enemies using its...