OESOPHAGUS STOMACH
ECHINODERMS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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true
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false
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Either A or B
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None of the above
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Detailed explanation-1: -The development of a head in evolution is known as cephalization. It is absent in echinoderms, which although having a bilateral ancestor develop into a pentaradial animal with no concentrated neural ganglia or sensory head region.
Detailed explanation-2: -Echinoderms are named for their spiny skin, which is covered by a thin layer of calcium carbonate plates and spines. Adult echinoderms have radial symmetry, but larvae have bilateral symmetry. Echinoderms have a unique water vascular system, with canals that extend along each body part.
Detailed explanation-3: -Echinoderms reproduce sexually. In most echinoderms, eggs and sperm cells are released into open water, and fertilization takes place when the eggs and sperm meet. This is called external fertilization, and is typical of many marine animals.
Detailed explanation-4: -Answer and Explanation: The correct answer is (b). Echinoderms do not have gills.