Chondrichthyes or cartilaginous fishes are jawed fish, have paired fins, paired nostrils, scales, two heart bears, and a framework that consists of cartilage instead of bone true. They are divided into two subclasses: Elasmobranchii (sharks, rays and skates) and Holocephali (Kimera, sometimes called ghost sharks, and sometimes separated into a class of its own).
framework
Cartilaginous skeleton. Notochord, which exist in the young, gradually replaced by cartilage. Chondrichthyes also had no ribs, so if they come out of the water, the body weight of the large species can crush their internal organs long before they limp.
Because it does not have the bone marrow, red blood cells are produced in the spleen and special tissue in the penis. they also produce an organ called Leydig's Organ which is only found in cartilaginous fish, although some do not have it. Another unique organ is the organ epigonal that may play a role in the immune system. Subclass Holocephali, highly specialized group, do not have both these organs.
framework
Cartilaginous skeleton. Notochord, which exist in the young, gradually replaced by cartilage. Chondrichthyes also had no ribs, so if they come out of the water, the body weight of the large species can crush their internal organs long before they limp.
Because it does not have the bone marrow, red blood cells are produced in the spleen and special tissue in the penis. they also produce an organ called Leydig's Organ which is only found in cartilaginous fish, although some do not have it. Another unique organ is the organ epigonal that may play a role in the immune system. Subclass Holocephali, highly specialized group, do not have both these organs.
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