OESOPHAGUS STOMACH
ECHINODERMS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Echinoidea, no arms, ball or disk shape
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Holothuroidea, elongated body, tentacles around the mouth
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Ophiuroidea, long thin legs, single organ set in central disk
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Crinoidea, upward-facing mouth, long feather-like arms
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Detailed explanation-1: -Sea urchins and sand dollars are examples of Echinoidea. These echinoderms do not have arms, but are hemispherical or flattened with five rows of tube feet that help them in slow movement; tube feet are extruded through pores of a continuous internal shell called a test.
Detailed explanation-2: -Sea urchins and sand dollars (Echinoidea) are a group of echinoderms that are spiny, globe or disk-shaped animals. Sea urchins and sand dollars are found in all the world’s oceans. Like most other echinoderms, they are pentaradially symmetrical (the have five sides arranged around a central point).
Detailed explanation-3: -Echinoidea is a class that belongs to the phylum Echinodermata. Species that belong to this class are the sand dollars, cake urchins, sea urchins, and heart urchins. Echinoids have an egg shaped, circular body which is hemispherical. They have skeletal plates that bear many movable spines and three jawed pedicellariae.
Detailed explanation-4: -Echinodermata (echinoderms), class: Echinoidea (sea urchins, heart urchins & sand dollars)
Detailed explanation-5: -Sea urchins (class Echinoidea) have no arms (Fig. 3.83 A). The radial body plan is spherical.