SCIENCE
ZOOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Choanocytes
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Tissues
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Pinacocytes
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Mesohyl
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Detailed explanation-1: -But nervous system is completely absent in sponges.
Detailed explanation-2: -The nerve cell is a eumetazoan (cnidarians and bilaterians) synapomorphy [1]; this cell type is absent in sponges, a more ancient phyletic lineage.
Detailed explanation-3: -Choanocytes are also called as the collar cells. These cells line the interior of the body of sponges. Choanocytes have flagella that propel water through the body and are used in feeding. Thus, the correct answer is option D.
Detailed explanation-4: -Internally, they do not have brains, stomachs, or other organs. This is because sponges evolved much earlier than other animals. In fact, sponges do not even have true tissues. Instead, their bodies are made up of specialized cells (cell-level organization) that do specific jobs.