Video Transcript
Which of the following organisms
belongs to the phylum Echinodermata? (A) Oyster, (B) starfish, (C)
octopus, or (D) snail.
Organisms that belong to the phylum
Echinodermata have an unsegmented and radially symmetrical body, meaning that it is
in one piece. And it is the same on both sides
and top and bottom. They also have a hard endoskeleton,
or inner skeleton, surrounded by an epidermidis, or skin.
Let’s determine which of these
answer choices falls into this category. Oysters, snails, and octopuses
belong to the phylum Mollusca. Organisms that belong to this
phylum secrete a hard shell, among other common characteristics. In addition, they do not have
endoskeletons. So they cannot be classified as
echinoderms. Therefore, we can eliminate answers
(A), (C), and (D).
Starfish do have unsegmented,
radially symmetrical bodies and a hard skeleton surrounded by an epidermidis. So the correct answer is (B). Starfish belong to the phylum
Echinodermata.
