Are there any fish without bones?

This article is going to cover everything about fish without bones.We will also discuss their habitats and types in this article

Overview

In this blog post we will discuss:

  • Are there any fish without bones?
  • Key specifications of cartilaginous fish
  • What are cartilaginous fish?
  • Habitat of cartilaginous fish
  • Types of cartilaginous fish
  • Fish without bones
  • Summary
  • Frequently asked questions

Are there any fish without bones?

Cartilaginous fish are considered as fish without bones:

  • The great shark
  • Tiger shark
  • Megalodon 
  • Giant freshwater stingray
  • Giant manta ray
  • Largetooth sawfish
  • Asian sea bass
  • Chimeras 

Key specifications of cartilaginous fish

Name Cartilaginous fish (1000 species)
Class Chondrichthyes (Huxley) 
Skeleton composition Cartilage (without bone tissue)
Types of cartilaginous fish SharksSkatesRays Chimeras 
Subclass Elasmobranchii Holocephali
Examples of fish without bonesgreat white sharktiger sharksMegalodongiant freshwater stingraygiant manta raylargetooth sawfish

What are cartilaginous fish?

Cartilaginous fish belong to class chondrichthyes & their endoskeleton is made up of cartilage.They are considered as jawed fish with flexible cartilaginous skeleton.

Characteristics of a cartilaginous fish:

  • Cartilaginous fish lack bone marrows and ribs.
  • RBCs are produced in spleen,the blood bank of cartilaginous fish
  • Tough tooth-like scales on their exoskeleton which is covered with dermal teeth or dermal denticles or minute placoid scales, which provides protection to cartilaginous fish.They have mucus glands too.
  • Notochords are present with complete and separate vertebrae.
  • Buccal cavity is vertically placed.
  • Cartilaginous fish have a heterocercal tail.
  • Chondrichthyans have 5-7 pairs of gills for breathing.
  • Chondrichthyans brains are composed of 8-10 pairs of cranial nerves,spinal cords and spinal nerves.
  • Their brain has a special electroreceptor,called Ampullae of Lorenzini,which helps them to sense electric fields in water.
  • Adaptive or acquired immune system.
  • Separate sexes and fertilization is internal.
  • Most cartilaginous fish are ovoviviparous, but some of them are viviparous too.
  • All cartilaginous fish are predaceous in nature. 

Habitat of cartilaginous fish

Cartilaginous fish are found all over the world, in a wide variety of waters from rays living in shallow waters, on a sandy bottom, to sharks living in the deep open ocean.They are mostly marine,but also found in some freshwater environments too.

Types of cartilaginous fish

Class Chondrichthyes has two subclasses:

  • Elasmobranchii- Subclass of cartilaginous fish consisting of  sharks and batoids.They don’t have a swim bladder and maintain their buoyancy with the help of their large livers which contain oil in them.
  • Holocephali-Subclass and ancient group of cartilaginous fish.They are with gill covers and have 4 gill slits.

Elasmobranchs are further divided into 3 categories:

  • Sharks
  • Skates 
  • Rays 
  • Sawfishes 

Holocephali has only one category of fish:

  • chimeras, or ratfishes or ghost sharks

Fish without bones

Detail of fish without bones:

The Great white shark

  • Scientific name- Carcharodon carcharias
  • Another names- The white shark,white pointer and great white shark
  • Conservation status- Vulnerable (slow reproduction is the main cause)
  • Habitat- Oceans of the United States,South Africa, Japan,Chile, marmara and bosporus sea.
  • Size- 20 feet long,females are larger than males
  • Weight – white sharks weigh about 520-1100kg
  • Lifespan- 70 years (longest lived)
  • Lifestages -Pups,young of the year, juveniles,subadults and adults
  • Speed-white sharks can swim at the speed of 56 km/hr.White sharks have strong,torpedo bodies and dynamic and powerful tails which help them to swim. 
  • Bite force-4000 PSI
  • Rendall is the largest white shark on record,19.7 feet long.
  • Considered as the most aggressive sharks in the world.

Tiger shark

  • Scientific name-Galeocerdo cuvier
  • Another names-maneater shark,leopard shark and spotted shark.
  • Conservation status- Near threatened
  • Habitat- tropical and warm temperate waters, Pacific islands 
  • Size-380 to 450 cm in total length
  • Weight-Tiger sharks weigh about 175-365 kg
  • Lifespan- 12 years 
  • Speed-Tiger sharks can swim at the speed of 32km/hr
  • Bite force-3300kg/cm square 
  • Their wedge shaped heads help them to turn quickly to one side during swimming.
  • Tiger sharks are considered as apex predators(garbage eaters) because of their broad range of diets.
  • Their gills help them to breathe under waters 
  • Considered as large macro predators and excellent scavengers.
  • If you compare tiger sharks with other shark species, they have better eyesight,sharp sense of smell and these qualities make them great nocturnal predators.

Megalodon

  • Scientific name-Otodus megalodon/Carcharocles megalodon
  • Another names-giant white shark,megatooth shark,big-tooth shark or meg.
  • Conservation status- extinct species
  • Habitat-Fossils in coast of Denmark and New zealand 
  • Size-33.5 to 58.7 feet long
  • Weight-30,000 to 65,000 kg
  • Adult females were larger than adult male megalodon 
  • Lifespan-88 to 100 years
  • Speed-Megalodon used to swim at the speed of  18 km/hour
  • Bite force- 108,500 to 182,200 newtons
  • Their teeth were thick and strong,designed to grab prey and break bones

Giant freshwater stingray

  • Scientific name- Urogymnus polylepis/Himantura chaophraya
  • Other names-Giant stingray,whipray and freshwater whipray.
  • Conservation status- Endangered (habitat degradation and fragmentation,fishing pressure and aquarium display) 
  • Habitat- rivers and estuaries in Borneo and Southeast asia
  • Size-16.5 feet long with tail
  • Weight-Giant freshwater stingray can weigh up to 1300 pounds
  • Lifespan-As such the data are not available, but as per some source they can live between 5-10 years
  • Speed-Giant freshwater stingray can swim at the speed of 32 km per hour.
  • Giant freshwater stingray are famous for their longest spines (15 inches) among ray species 
  • Giant freshwater stingrays are the only cartilaginous species which are not found in salt water regions.
  • Giant freshwater stingrays are not so aggressive and contain a toxin which has the ability to pierce bones.

Giant manta ray

  • Scientific name-Mobula birostris
  • Another names- Giant oceanic manta ray,oceanic manta ray,devil fish
  • Conservation status- Vulnerable
  • Habitat- tropical,subtropical and temperate waters
  • Size-15-23 feet
  • Weight-Giant manta ray can weigh up to1600 (fully adult)
  • Lifespan- they can live up to 40 years 
  • Speed-Giant manta ray fish can swim at the speed of 14.5km per hour and can increase their speed to 35km per hour when in danger.
  • Bite force- They can’t bite,their body size is sufficient to escape harmful predators.
  • Wingspan-29 feet 
  • Largest ray in the world
  • Famous for their horn shaped fins
  • Feeding – filter feeders and mainly feed on zooplanktons
  • Giant manta ray fish can be seen in public aquariums too

Largetooth sawfish

  • Scientific name-Pristis pristis/Pristis microdon/Pristis perotteti
  • Other names-common sawfish,wide sawfish,freshwater sawfish,river sawfish,northern sawfish and Leichhartd’s sawfish.
  • Conservation status- Critically endangered 
  • Habitat- Lake Nicaragua,adults are mostly found in shallow marine waters and brackish systems while juveniles are found in freshwater systems.
  • Size-Range between 6.6-8.2 feet long
  • Weight-Largetooth sawfish can weigh up to 1102-1323 pounds
  • Lifespan- Unknown 
  • Speed- They don’t have a swim bladder  and swim at a speed of 0.98 mph with the help of their fins.
  • Bite force- They have a rostrum to thrash a fish into halves.
  • Sawfish are considered as the most endangered elasmobranch in the world.
  • Sawfish were hunted in ancient times for their fins for medicinal purposes.

Asian sea bass

  • Scientific name-Lates calcarifer
  • Other name-barramundi, bhetki fish
  • They belongs to a family of catadromous fish 
  • Habitat -Indo west pacific region
  • Size-Range between-0.6 to 1.2m
  • Weight-Asian sea bass can weigh up to 60 kgs
  • Their large silver scales become light or dark depending upon the environment.
  • They are salt and freshwater sportfish
  • Famous recreational fish 
  • Juvenile asian sea bass can be kept in aquariums.
  • They are famous for Australian, Bengali, Goan and Thai cuisines.

Chimeras

  • Other names- ratfishes, ghost sharks,spookfish, rabbitfish, elephant fish.
  • Conservation status-not extinct
  • Size-4.5 feet in length,24 to 80 inches in length.
  • Weight -chimeras can weigh up to 2.5 kgs.
  • Considered as distant relatives of sharks.
  • Long tapering bodies with huge heads.
  • Male chimeras have retractable sexual appanddges on their forehead.This is very unique thing about male chimeras.
  • Rounded or cone shaped snout.
  • Chimeras have bigger pectoral and pelvic fins.
  • Chimeras are mostly silver and black in colour.
  • They too have electroreceptors called ampullae of lorenzini.
  • They are weak swimmers,get caught easily and die quickly once out of water.
  • Habitat-Chimeras are found in both temperate and cold waters.
  • Total 47 species of chimeras are present.
  • Chimeras are edible but they also release some chemicals which are poisonous.
  • Chimeras have slow growth rate and long lifespan

Summary

  • Most of the cartilaginous fish are under critically endangered category,So it is very important to not disturb their natural habitat.
  • Fish without bones have no swim bladders,so they maintain their buoyancy with the help of oil stored in their livers.
  • Cartilaginous fish cartilage is softer and flexible as it does not have more amount of calcium,which is required to make bones rigid.
  • Most of the cartilaginous fish can survive in marine or saltwater habitats.They can be found throughout the world ocean and sea.

Frequently asked questions on fish without bones

What are the main differences between elasmobranchii and holocephali?

The main difference between elasmobranchii and holocephali is their gill structures and their growth inside embryos.Elasmobranchs are without gill covers and have 5-7 external gill slits while holocephali are with gill covers and has 4 gill slits.

Are tooth and spine of cartilaginous fish made up of bones?

The tooth and spines of cartilaginous fish is also made up of cartilage.The whole body from tooth to spines is made up of cartilage not bones.

References 

https://en.wikipedia.org/wiki/Chondrichthyes#Skeleton
https://www.britannica.com/animal/chimaera

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