Fish
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A fish is an aquatic, anamniotic, gill-bearing vertebrate animal with a tough cranium to protect the brain, but lacking limbs with digits. Fish can be grouped into the more basal jawless fish and the
Dunkleosteus was a giant Devonian armoured placoderm, c. 400 mya.
Largest: whale shark
Smallest: e.g. Paedocypris progenetica
Fish fin
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Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and lift, which help the fish swim. Apart from the tail or caudal fin, fish fins have no direct
Skeleton of a lingcod, a ray-finned fish
Lobe-finned fishes, like this coelacanth, have fins that are borne on a fleshy, lobe-like, scaly stalk extending from the body. Due to the high number of fins it possesses, the coelacanth has high manoeuvrability and can orient its body in almost any direction in the water.
Pectoral fin with fleshy lobe of Latimeria chalumnae (Citron / CC-BY-SA-3.0)
Skeleton of the pectoral girdle and fin of the extant coelacanth Latimeria chalumnae (Citron / CC-BY-SA-3.0)