EasyBiologyHigh School (11–12)Diversity of Living Organisms › Chordates and VertebratesConceptualBoard Exam
A fish market sells six kinds of fish: Scoliodon, Labeo, Pristis, Catla, Trygon and Clarias…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A fish market sells six kinds of fish: Scoliodon, Labeo, Pristis, Catla, Trygon and Clarias. Sort them into the two classes of fishes, and give two features you could check to be sure.
Need a reminder? The key ideaShow
Cyclostomata: no jaws, 6 to 15 pairs of gill slits, no scales, no paired fins. Chondrichthyes: cartilage, ventral mouth, separate gill slits with no operculum, placoid scales, no air bladder. Osteichthyes: bone, terminal mouth, four pairs of gills under an operculum, air bladder. Amphibia: moist skin without scales, cloaca, a three-chambered heart, gills, lungs and skin for breathing.
The worked solution
Have you tried it?
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. Chondrichthyes. Scoliodon, the dogfish, Pristis, the sawfish, and Trygon, the stingray, have skeletons of cartilage.
Step 2. Osteichthyes. Labeo, the rohu, Catla, the katla, and Clarias, the magur, have bony skeletons.
Step 3. Features to check. A cartilaginous fish has separate gill slits with no operculum, and a mouth on the lower side. A bony fish has an operculum over its gills and a mouth at the front.
Answer: Chondrichthyes: Scoliodon, Pristis, Trygon. Osteichthyes: Labeo, Catla, Clarias. Check for an operculum and the position of the mouth.
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