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Bony fish can be further divided into those with lobe fins and those with ray fins. Lobe fins have the form of fleshy lobes supported by bony stalks which extend from the body. [16] Lobe fins evolved into the legs of the first tetrapod land vertebrates, so by extension an early ancestor of humans was a lobe-finned fish.
Comparison between A) the swimming fin of a lobe-finned fish and B) the walking leg of a tetrapod. Bones considered to correspond with each other have the same color. In a parallel but independent evolution, the ancient reptile †Ichthyosaurus communis developed fins (or flippers) very similar to fish (or dolphins).
Mahi-mahi have compressed bodies and one very long dorsal fin extending from the head almost to the tail fin. Mature males have distinctive "foreheads"; it grows as the fish matures and often protrudes well above the body proper, which is streamlined by the musculature of the back. This "hump" is a sexually dimorphic feature; females have a ...
Mandarinfish lack scales and have a layer of smelly and bitter slime which blocks out disease and probably discourages predators, implying their bright coloration is aposematic. [63] Anglerfish have loose, thin skin often covered with fine forked dermal prickles or tubercles, but they do not have regular scales. They rely on camouflage to avoid ...
A common bottlenose dolphin (Tursiops truncatus). A dolphin is an aquatic mammal in the clade Odontoceti (toothed whale).Dolphins belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (the brackish dolphins), and possibly extinct Lipotidae (baiji or Chinese river dolphin).
A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found in most fish, in mammals such as whales, and in extinct ancient marine reptiles such as ichthyosaurs ...
The precise nature of its purported scales has not been studied in detail, but they appear to be structurally different from pangolin scales. Anomalures also have scales on their tail undersides. [8] Foot pad epidermal tissues in most mammal species have been compared to the scales of other vertebrates.
Derived from placoid scales, they have a thick coat of enamel, but without the underlying layer of dentin. These scales cover the fish's body with little overlapping. They are typical of gar and bichirs. Cycloid scales are small, oval-shaped scales with growth rings like the rings of a tree. They lack enamel, dentin, and a vascular bone layer.