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Elasmobranchii is one of the two subclasses of cartilaginous fish in the class Chondrichthyes, the other being Holocephali . Members of the elasmobranchii subclass have no swim bladders, five to seven pairs of gill clefts opening individually to the exterior, rigid dorsal fins, and small placoid scales. The teeth are in several series; the ...
The rhenanids were once presumed to be the most primitive, or at least the closest to the ancestral placoderm, as their armour was made of unfused components—a mosaic of tubercles—as opposed to the solidified plates of "advanced" placoderms, such as antiarchs and arthrodires. However, through comparisons of skull anatomies, rhenanids are ...
National Geographic Image Collection (1888–present), collection of more than 10 million digital images, transparencies, b&w prints, early auto chromes, and pieces of original artwork New York Daily News (1880–2007), online photo archive DailyNewsPix, with photographs dating back to 1880 New York Public Library: ≈ 30% Public domain
Risso's illustration of the marbled electric ray, accompanying his original species description. French naturalist Antoine Risso described the marbled electric ray as Torpedo marmorata in his 1810 Ichtyologie de Nice, ou histoire naturelle des poissons du département des Alpes maritimes (Ichthyology of Nice, or natural history of fishes in the Alpes-Maritimes).
Agnatha (/ ˈ æ ɡ n ə θ ə, æ ɡ ˈ n eɪ θ ə /; [3] from Ancient Greek ἀ-(a-) 'without' and γνάθος (gnáthos) 'jaws') is a paraphyletic infraphylum [4] of non-gnathostome vertebrates, or jawless fish, in the phylum Chordata, subphylum Vertebrata, consisting of both living (cyclostomes) and extinct (conodonts, anaspids, and ostracoderms, among others).
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The pair then parts, the female being left with scars on her fin. [33] [12]: 46 The fertilized eggs develop within the female's oviduct. At first, they are enclosed in an egg case while the developing embryos absorb the yolk. After hatching, the pups remain in the oviduct and receive additional nutrition from milky secretions called histotroph ...
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