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Do all sea creatures that have scales have to have fins?

Do we know of any sea creatures that have only scales without fins?

I'm especially interested in fish that have scales but no fins.

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The 'fish' part of this question may be circular, since fishes are a paraphyletic group. From wiki: "A fish is any member of a paraphyletic group of organisms that consist of all gill-bearing aquatic craniate animals that lack limbs with digits". In that definition, 'lacks limbs with digits' is a near-synonym of 'has fins' (the alternative being 'has lost all limbs'). If the group 'fish' were defined in the normal way (i.e., by phylogeny), then all of the groups mentioned in @Alan Boyd 's answer would count as fishes! – bshane Oct 24 '15 at 2:03
up vote 5 down vote accepted

How about marine reptiles? Sea snakes have a paddle-like tail, so perhaps you would claim that as a fin, but maybe marine iguanas would qualify? And, of course, sea turtles.

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Thanks Alan. Maybe you know of fish that answer the criterion? – MichaelS Oct 28 '12 at 16:07
Definitely not. Since the tail is the caudal fin, this hypothetical finless fish would have no means of locomotion. – Alan Boyd Oct 28 '12 at 16:44
Eels, but they have caudal fins... Would you consider rays to be finless?... Just checked, a ray's wings are considered fins... – AMR Oct 23 '15 at 21:34

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