Essay On Urchins

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Sea urchin Introduction: The name "urchin" is an old word for hedgehog, which sea urchins resemble. Sea urchins are small and spiny animals that are members of the phylum Echinodermata, which also includes sea stars, sea cucumbers, brittle stars, and crinoids. There are nearly 200 different species of identified sea urchin with various shapes, sizes and living in different environments. As some sea urchin living 200 years or more, they are considered the longest living animals on earth. Sea urchins have a certain regenerative ability. For example, if a spine is damaged or lost, the animal can regenerate it. However, in case of the mass spine damage/loss, the regeneration becomes beyond the ability of the urchin. Distribution and habitats:…show more content…
Description: Sea urchins have a five-fold symmetric body with round shell and long spines that come off it. Typically sea urchins are small, ranging from about 3 cm to 10 cm in diameter, and their bodies are covered with a spiny shell. The shells are made up of packed, fitted plates which protect them from being damaged. In regard to the spines outlining their shell, these help the sea urchin to camouflage or protect them against predators. Sea urchins can vary greatly in color while the most frequently seen colors are black, olive, red, brown, purple and light pink. The mouth is found on the middle on the underside of the sea urchin's body and has five tooth-like plates that sea urchins use to ingest algae and break down other foods they consume. The anus of the sea urchin is located on the top of the body. Instead of circulatory system, sea urchins have water-vascular system which comprises of water-filled channels that run through the body of the sea urchin and functions as the

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