Cartilaginous Fish vs. Bony Fish, differences between them
There are two types of fish that usually are contentious, and give a lot of people a hard time telling apart. If you can learn the differences between these two types of fish, it can be very easy for you to understand and tell them apart where necessary. Technically, the most obvious disparity between bony vs cartilaginous fish comes from the fact that the skeleton of bony fish is made of bones alone, while that of cartilaginous fish is made of cartilage.
There are more than 20,000 fish species in the world. Of the class Chordata, Pisces is a super class. The reason for this is because more than half of the chordates are generally fishes. From this category, fishes are classified as either osteichthyes or chondrichthyes (bony fish or cartilaginous fish). This brings us to the comparison between bony vs cartilaginous fish.
Bony Fish
This category of fish is also referred to as Teleostomi. It is also considered the largest class in Phylum Chordata. These fish are widely recognized because of the following characteristics:
- Their endoskeleton is entirely made of bone
- They have anterior tip mouth opening
- They can either be fresh water or marine water fishes
- Their exoskeleton is made up of cycloids (thin bony plates), aligned based on whether the outer edges are spiny or smooth
- They have an operculum on either side of their gills
- They possess an air bladder that also performs hydrostatic functions
- Their tail fin is homocercal
- They fertilize their eggs externally
Some of the fish in this category include flying fish, globe fish, sea horses and eels.
Cartilaginous Fish
This category of fish is also referred to as Elasmobranchi. In this category you will primarily find marine fishes. Therefore, you should not find any fresh water fish in this group. They generally possess the following characteristics:
- Their endoskeleton is primarily made of cartilage
- Their exoskeleton is made of placoid (very small denticles coated with lots of sharp enamel)
- The buccal cavity of these fishes is ventrally positioned
- The position of their tail finds is heterocercal
- On either side, they have 5 gills that are overly exposed, so they do not have an operculum
- Their mode of fertilization is through internal mechanisms
Some of the common fish in this group include dog fish, skates, electric ray torpedo, and sharks. If you understand these differences, it is easier for you to tell the two types of fish apart.