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Difference between Cartilaginous Fish and Bony Fish

November 11, 2024
written by Almas Anwar

The main difference between cartilaginous fish and bony fish is in their skeleton. Cartilaginous fish are marine animals and have endoskeleton made entirely of cartilage. While bony fish are found in fresh water as well as marine water, and their endoskeleton is made of bones.

Likewise, the exoskeleton of cartilaginous fish is made of ‘placoid’ scales, known as denticles. While exoskeleton of bony fish may contain different types of scales cycloid, ctenoid, or ganoid.

Difference between Cartilaginous and Bony fish image

Fishes are classified into two groups: Chondrichthyes and Osteichthyes (cartilaginous and bony fish). Based on this classification, both the groups have different anatomy and characteristics.

Cartilaginous fish Vs. Bony fish

Here are the key differences between cartilaginous fish and bony fish:

CharactersCartilaginous FishBony Fish
ClassificationPhylum- Chordates Class- ChondrichthyesPhylum- Chordata Class- Osteichthyes
HabitatFound in marine waterFound in both; marine and freshwater
SkeletonMade up of cartilageMade up of bones
ScalesPlacoid (teeth-like) scales that are embedded with the skin, called denticles.Can have different types of scales: cycloid (smooth and round), ctenoid (rough and comb-edged), and ganoid (thick).
Gills5-7 pairs of gills4 pairs of gills
Alternative nameElasmobranchii  Teleostomi
Mouth positionMouth located on the underside  Have moth at the front tip
Jaw setHave a single set of oral jaws with sharp teethHave two sets of oral jaws
Air BladderHave an oil-filled liver for buoyancy.Have a swim bladder for buoyancy.
FertilizationExhibits internal fertilization and give birth to live young (viviparous), or lay eggs (oviparous)External fertilization
ExcretionExcretes ureaExcretes ammonia
Number of speciesMore than 970 species have been identifiedAlmost 27,000 species that are identified worldwide
ExamplesExamples include: Sharks, Rays, Skates.Examples include: Salmon, Rohu, Trout, Seahorse, Flying fish.