OESOPHAGUS STOMACH
ECHINODERMS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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A flexible endoskeleton divided into rather thick, fleshy rays
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Minute calcified plated embedded in fleshy skin
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A flattened, inflexible endoskeleton made up of fused calcified plates
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None of these
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Detailed explanation-1: -Features: They got their name because they resemble a one-dollar coin. Like other echinoderms, sand dollars are symmetrical along five axes, and have tube feet and spines. Their flat disk-like shape is an adaptation for life on the sea bottom where they gather detritus.
Detailed explanation-2: -Their bodies look like pin cushions. The sea star’s skeleton, like the sea urchin’s, is an endoskeleton consisting of small plates of calcium carbonate embedded in the epidermis. These plates, called ossicles, are much smaller than those of sea urchins.
Detailed explanation-3: -Sand Dollars are members of the phylum Echinodermata, and their relatives include sea cucumbers, sea stars and sea urchins among others. Characteristics of this phylum include spiny skin, tube feet for locomotion, and radial symmetry. The flower-like pattern seen on the test of sand dollars is used for gas exchange.
Detailed explanation-4: -Most sea stars, though not all, have five arms. Sea urchins have five arms but roll them into a ball and cover that with long spines. Sand dollars are just sea urchins that have been flattened like a pancake and have very short spines. Echinoderms can regenerate body parts.