The largest fish in the world belong to the taxonomic class of manta rays, and as you now know these are the largest rays. But let’s go part by part.
Manta rays are fish like sharks, salmon and marlin. However, they differ from the latter two by having a skeleton composed of cartilage and not bone tissue; In short, they lack bones. Scientists differentiate bony fish and cartilaginous fish by their taxonomy and fish with cartilaginous skeleton are classified in the class Chondrichthyes which includes the Elasmobranchii and Holocephali subclasses. Manta rays are included in the first subclass, along with other species of sharks and rays, sawfish and electric rays.
The origin of manta rays
Information on the evolution of manta rays is not exactly abundant, but it seems clear. The first fish that existed were creatures of cylindrical body without jaws that existed during the Cambrian period. Over time the fish diversified and appeared several groups from which today’s fish evolved.
The first cartilaginous fish lived about 395 million years ago, in the middle of the Devonian period, according to fossil records. They probably came from placodermos thorny sharks, and in fact, some placodermos artwork exhibit some resemblance to modern rays. The first kind of primitive sharks were called Cladoselache, and includes a similar current exemplary species with gills and smooth teeth, maintaining a carnivorous diet. It was devoid of claspers or copulatory organs as the ones they now have: the elasmobranches.
During the Silurian period, about 421 million years ago, the Holocephala and Elasmobranchii classes diverged, differentiating the chimeras of sharks and rays; the latter two have many similarities to each other. Already in the Carboniferous period sharks and rays separated. This period was a productive time for elasmobranches, as there was a great diversity of them.
Morphologically, it is relatively easy to differentiate sharks of fusiform body from rays and manta rays of flattened body. Many scientists believe rays originated from sharks about 170 million years ago during the Jurassic and roamed the seas. These primitive rays evolved to adapt to life on the seabed. One of the first ray genres were Cyclobatis, with circular libs and short tail with stinger.
Manta rays are believed to come from the ray species inhabiting the ocean floor. Manta rays and members of the genus Mobula evolved about 20 million years ago. The rays that gave rise to manta rays were benthic species that performed wavelike motions to swim near the arena.
Current manta rays evolved about 5 million years ago. One of the most distinctive features of manta rays are their enormous and triangular pectoral fins; they were developed over the course of the years until they differentiated more clearly from “wingless” bodies the other species of rays form. Furthermore, evolution took over of making the dangerous stinger to disappear, but manta rays kept the flattened body and tail like a whip.
The fossil record of manta rays is not very rich since cartilage is not preserved as well as bone, but fossils have been found in North America that date back to the Oligocene, Miocene and Pliocene. Today, many experts agree that manta rays are the most developed elasmobranches of all in terms of morphology or physical characteristics.
