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The olfactory lobes are very large in fish that hunt primarily by smell, such as hagfish, sharks, and catfish. Behind the olfactory lobes is the two-lobed telencephalon, the structural equivalent to the cerebrum in higher vertebrates. In fish the telencephalon is concerned mostly with olfaction. [59] Together these structures form the forebrain.
A fish (pl.: fish or fishes) is an aquatic, anamniotic, gill-bearing vertebrate animal with swimming fins and a hard skull, but lacking limbs with digits.Fish can be grouped into the more basal jawless fish and the more common jawed fish, the latter including all living cartilaginous and bony fish, as well as the extinct placoderms and acanthodians.
The fish include the jawless Agnatha, and the jawed Gnathostomata. The jawed fish include both the cartilaginous fish and the bony fish. Bony fish include the lobe-finned fish, which gave rise to the tetrapods, the animals with four limbs. Despite their success, vertebrates still only make up less than five percent of all described animal species.
Shark skeletons are very different from those of bony fish and terrestrial vertebrates. Sharks and other cartilaginous fish (skates and rays) have skeletons made of cartilage and connective tissue. Cartilage is flexible and durable, yet is about half the normal density of bone. This reduces the skeleton's weight, saving energy. [32]
The diversity of jawed vertebrates may indicate the evolutionary advantage of a jawed mouth; but it is unclear if the advantage of a hinged jaw is greater biting force, improved respiration, or a combination of factors. Fish, like many other organisms, have been greatly affected by extinction events throughout natural
A newfound fossil of a jawless fish is the oldest known vertebrate cranium preserved in 3D. The 455 million-year-old find could illuminate how vertebrate heads evolved.
Chondrichthyes (/ k ɒ n ˈ d r ɪ k θ i iː z /; from Ancient Greek χόνδρος (khóndros) ' cartilage ' and ἰχθύς (ikhthús) ' fish ') is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage.
Zangroniz said studies only use a few species of fish and don't represent the more than 30,000 fish species that exist. She added pain is measured in mammals on the grimace scale, often seen in ...