Difference Between Bony Fish and Cartilaginous Fish

The difference between bony fish and cartilaginous fish is the study of all the differences that make the two groups of fish separate. Bony fish and cartilaginous fish are two diverse groups of aquatic vertebrates. Bony fish and cartilaginous fish both share certain similarities like the presence of gills and fins. But bony fish and cartilaginous fish are fundamentally different, based on their skeletal structure.

Bony fishes have a bony skeletal system due to which they are called so whereas cartilaginous fishes have a skeletal system made of cartilage due to which the group derived its name. In this article, we will look into the general characteristics of bony and cartilaginous fishes and their characteristic differences and similarities.

Difference Between Bony Fish and Cartilaginous Fish

Following are some of the common differences between bony and cartilaginous fishes:

Parameters	Bony Fish	Cartilaginous Fish
Skeletal System	Made of bones	Made of Cartilages
Types of Scales	Cycloid or Ctenoid scales	Placoid scales
Buoyancy is Maintained by	Swim bladder	Large oily liver
Birth of Ofsrping	Oviparous	Oviparous as well as viviparous
Classification	Belong to class Osteichthyes	Belong to class Chondrichthyes
Operculum (gill cover)	Absent	Present
Tail (Caudal fin)	Homocercal (symmetrical upper and lower lobes)	Heterocercal (asymmetrical upper and lower lobes)
Habitat	Found in both freshwater and marine habitats	Found mainly in marine habitats except for a few freshwater species
Examples	Tilapia, Hilsa, Rohu, Tuna, Trout, etc.	Sharks, Rays, Guiterfish, etc.

What is Bony Fish?

Bony fishes belong to the class Osteichthyes. They fall under the superclass Pisces. The characteristic feature that distinguishes them from other members of the superclass Pisces is the presence of an ossified skeleton made of bone-forming tissues. They have streamlined bodies, specialized fins for movement in water bodies, scales in their body, swim bladders to maintain buoyancy underwater, etc. characteristics that help them to survive underwater.

Characteristics of Bony Fish

Some of the characteristic features of bony fish are:

• They have bony skeletons due to the ossification of bone tissues.
• They have scales over their body for protection.
• They have an air-filled swim bladder that helps them to maintain buoyancy.
• They have paired fins in the pectoral and pelvic regions of the body.
• They have unpaired fins in dorsal, caudal, and anal regions of the body.
• They have a specialized “lateral line system” sensory organs throughout the body to detect any vibration under water and changes in water pressure.
• They mainly show external fertilization with the help of water as a medium.
• They are found in both freshwater and marine habitats.
• Examples: Tilapia (freshwater), Catfish (freshwater), Sardine (marine), Herring (marine), Goldfish (freshwater), Salmon (freshwater and marine), Trout (freshwater), Hilsa (freshwater), Rohu (freshwater), etc.

What is Cartilaginous Fish?

Cartilaginous fishes in the class Chondrichthyes. They fall under the superclass of Pisces. The characteristic feature of this class is the presence of a cartilaginous skeleton instead of a usual bony one. They lack swim bladders instead have large, oily livers for buoyancy. However, most of them depend on constant swimming to remain afloat. They have placoid scales which are small, hard dentine-like structures that help to remove water resistance during swimming.

Characteristics of Cartilaginous Fish

Some most common characteristic features of cartilaginous fishes are;

• Their skeleton is made of cartilage.
• They have small tooth-like placoid scales.
• They respire through gills.
• They lack swim bladders and instead have large, oily livers to maintain buoyancy.
• Some of the members are apex predators as well as scavengers.
• They show oviparity as well as viviparity.
• They have a specialized sensory organ called “ampullae of Lorenzini” that helps to detect any movement underwater.
• They mostly have a single dorsal and caudal fins, and a pair of pectoral and pelvic fins.
• Examples: Sharks (marine), Stingrays (marine & freshwater), Sawfish (marine), Manta rays (marine), Guitarfish (freshwater), etc.

Similarities Between Bony Fish and Cartilaginous Fish

Even though the two classes of Pisces differed from each other, there are still some similarities that are seen:

• Both the classes are vertebrates.
• Both classes use gills for respiration.
• Both the classes use fins for locomotion and navigation.
• Both classes show an ectothermic mode of homeostasis.
• Both the classes have to perform internal osmoregulation to maintain salt and water balance in their bodies.
• Both classes have well-developed muscular systems to survive underwater.
• Both classes mostly have streamlined bodies to move easily underwater.
• Both classes have a wide range of environmental and economic importance.

FAQs on Bony Fish and Cartilaginous Fish

What is the Difference Between Bony and Cartilaginous Fish?

The main difference between bony and cartilaginous fish is the presence of bony and cartilaginous skeletons respectively in them.

How are Bony Fish Different from Cartilaginous Fish in Terms of Swimming?

Bony fishes use their fins extensively for swimming whereas cartilaginous fishes do not use their fins for swimming instead they depend on the movement of their body and tail for movement.

What Traits do Bony Fish and Cartilaginous Fish have in Common?

There are many similarities between them but the main similarity is both of the classes are vertebrates and use gills for respiration.

What is Different About How a Bony Fish and a Cartilaginous Fish Control its Buoyancy?

Bony fishes use swim bladders whereas cartilaginous fishes use large oily livers and their secretions to maintain buoyancy.

What is the Main Difference Between Bony Fish and Cartilaginous Fish Scales?

Bony fishes have more flexible cycloid or ctenoid scales whereas cartilaginous fishes have hard small placoid scales.

What are 5 Examples of Cartilaginous Fish?

Five examples of cartilaginous fish are Blacktip Reef Shark, Bonnethead Shark, Electric Rays, Epaulette Shark, Great White Shark.