#CHIMERA ANIMAL SKIN#

†Suborder Myriacanthoidei Patterson 1965 (Late Triassic-Late Jurassic).

† Squaloraja Europe, Early Jurassic ( Hettangian- Sinemurian).

†Suborder Squalorajoidei Patterson 1965 (Early Jurassic).

There are 50 extant species in six genera and four families are described an additional three genera and two families are only known from fossils): A preliminary study found 8% of species to be threatened. Chimaeras also have some characteristics of bony fishes.Ī renewed effort to explore deep water and to undertake taxonomic analysis of specimens in museum collections led to a boom during the first decade of the 21st century in the number of new species identified. In some classifications, the chimaeras are included (as subclass Holocephali) in the class Chondrichthyes of cartilaginous fishes in other systems, this distinction may be raised to the level of class. Chimaericola leptogaster ( Chimaericolidae) is a monogenean parasite of the gills of Chimaera monstrosa the species can attain 50 mm (2.0 in) in length. The extant species fall into three families-the Callorhinchidae, Rhinochimaeridae and Chimaeridae with the callorhinchids being the most basal clade.Īs other fish, chimaeras have a number of parasites. Unlike modern chimaeras, Mesozoic representatives are often found in shallow water settings. The earliest known remains attributable to modern chimaeras are known from the Early Jurassic ( Pliensbachian) of Europe, but egg cases from the Late Triassic of Yakutia, Russia and New Zealand that resemble those of rhinochimaerids and callorhinchids respectively indicates that they had a global distribution prior to the end of the Triassic. The oldest known Chimaeriform is Protochimaera from the Early Carboniferous (338-332 million years ago) of Russia, which is more closely related to modern chimeras (Chimaeroidei) than any other known extinct groups of Chimaeriformes. The group containing Chimeras and their close relatives ( Holocephali) is thought to have originated about 420 million years ago during the Silurian. DNA sequencing has become the preferred approach to understanding speciation. Tracing the evolution of these species has been problematic given the paucity of good fossils. Most vertebrates have an enamel of apatite. They are made of osteodentin and is covered by an enamel called pleromin formed by mesenchyme-derived cells and made by the mineral whitlockite. These are unique among vertebrates due to their mineralization. Instead of sharks' many sharp and replaceable teeth, they have just three pairs of large permanent grinding tooth plates. They also have gill covers or opercula like bony fishes. They also differ from sharks in that their upper jaws are fused with their skulls and they have separate anal and urogenital openings. The females lay eggs in spindle-shaped, leathery egg cases. However, unlike sharks, male chimaeras also have retractable sexual appendages on the forehead (a type of tentaculum) and in front of the pelvic fins. They also use electroreception to find their prey.

They use these fins to 'fly' through water.Ĭhimaeras resemble sharks in some ways: they employ claspers for internal fertilization of females and they lay eggs with leathery cases. For defense, most chimaeras have a venomous spine in front of the dorsal fin.

#CHIMERA ANIMAL SKIN#

Their skin is smooth and naked, lacking placoid scales (except in the claspers), and their color can range from black to brownish gray. Like other members of the class Chondrichthyes, chimaera skeletons are composed of cartilage. In many species, the snout is modified into an elongated sensory organ. They grow up to 150 cm (4.9 ft) in length, although this includes the lengthy tail found in some species. They have elongated, soft bodies, with a bulky head and a single gill-opening. They live in all the oceans except for the Arctic and Antarctic oceans. Consequently, these are also among the few species from the chimaera order kept in public aquaria. Exceptions include the members of the genus Callorhinchus, the rabbit fish and the spotted ratfish, which locally or periodically can be found at shallower depths. Visible on its snout are tiny pores which lead to electroreceptor cells.Ĭhimaeras live in temperate ocean floors down to 2,600 m (8,500 ft) deep, with few occurring at depths shallower than 200 m (660 ft). Deep-sea chimaera photographed by the NOAAS Okeanos Explorer.

Chimera animal