On a beach, Aditi finds an oyster shell with a shiny inner layer.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
On a beach, Aditi finds an oyster shell with a shiny inner layer. Her uncle says that a pearl forms inside one kind of oyster. (a) Name the pearl oyster and its phylum. (b) Which soft layer of the body lines the shell? (c) Where are the gills of this animal, and what two jobs do they do?
Need a reminder? The key ideaShow
Arthropoda: the largest phylum; chitin exoskeleton, jointed appendages, head, thorax and abdomen, open circulation, malpighian tubules; insects have 6 legs, spiders 8, crabs 10. Mollusca: head, muscular foot, visceral hump, mantle, radula, usually a shell; Pila, Pinctada, Sepia, Loligo, Octopus. Echinodermata: calcareous ossicles, water vascular system, radial adult and bilateral larva, no excretory system; Asterias, Echinus, Antedon, Cucumaria, Ophiura. Hemichordata: proboscis, collar and trunk; proboscis gland; Balanoglossus, Saccoglossus.
The worked solution
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Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The animal. The pearl oyster is Pinctada, a mollusc.
Step 2. The lining. The soft, spongy mantle covers the visceral hump and lines the shell.
Step 3. The gills. Feather-like gills lie in the mantle cavity. They serve for breathing and excretion.
Answer: (a) Pinctada, Mollusca; (b) the mantle; (c) in the mantle cavity, for breathing and excretion.
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