How are chondrichthyes economically important?
Economic value of rays About 126,000 short tons (roughly 114,000,000 kilograms) of rays are marketed for food in various countries about the world, principally in Europe and Asia. By-products in local demand are skins of scaleless species for drumheads; those of scaly species are used for shagreen.
How do chondrichthyes get food?
It is well documented that species within the chondrichthyes feed at all trophic levels, from plankton through to large marine mammals (Motta and Wilga 2001). Some species have very specific prey preferences.
What are characteristics of chondrichthyes?
- They are mostly marine fishes.
- They contain a pair of jaws.
- Whale sharks are the second largest vertebrate and the largest fish.
- The mouth is present ventrally.
- They contain cartilaginous endoskeleton, the deposits of calcium salts provide strength to it.
What is the importance of cartilage in fishes?
Sharks, rays, skates, and chimaeras (also know as rat fishes) all have cartilaginous skeletons. Cartilage is less dense than bone, allowing sharks to move quickly through the water without using too much energy.
What is the economic importance of fishes?
Economic importance of fishes: Fishes are a source of nutritious food as they are rich in proteins, vitamins (A, D, and K), carbohydrates, fats, and minerals. They also yield a number of by-products that hold commercial value.
Why are all the chondrichthyans restricted to an aquatic environment?
Estuaries, whose shallow waters provide invaluable nurseries for chondrichthyans are being destroyed or polluted. Similarly, certain freshwater systems are becoming increasingly degraded by pollution, making them inhospitable to indigenous species.
What is the economic importance of shark?
From a strictly economic perspective, sharks may generate revenue through fishing and through ecotourism. For the fishery, sharks represent a source of protein, leather, cartilage, oil, and fins, which is important for several communities in both developed and developing nations .
What are the evolutionary characteristics of the class Osteichthyes?
Class – Osteichthyes Bony fishes share several distinguishing features: a skeleton of bone, scales, paired fins, one pair of gill openings, jaws, and paired nostrils. Osteichthyes includes the largest number of living species of all scientific classes of vertebrates, more than 28,000 species.
What do dermal denticles help with?
Shark skin is covered by tiny flat V-shaped scales, called dermal denticles, that are more like teeth than fish scales. These denticles decrease drag and turbulence, allowing the shark to swim faster and more quietly.
What is the importance of cartilage in their life?
Why do we need JOINT cartilage? Hyaline, or articular, cartilage covers the ends of bones to create a low-friction environment and cushion at the joint surface. When cartilage in the joint is healthy, it effectively allows fluid bending/straightening motions and protects the joint against weight-bearing stresses.
What is economic importance of catfish?
Catfish are of considerable economic importance for aquaculture and recreational fisheries. Its global importance is increasing as several countries in Asia, such as China and Vietnam, are now heavily involved in catfish aquaculture (Liu, 2008).
What is the economic importance of fish farming in Nepal?
Fisheries play an important role in increasing the Nepalese economy as well as sustaining livelihood of some ethnic groups of our country. With the increased demand of fish, pisciculture have also increased to a great extend. Due to the rise in fish culture, there has been also rise in fish diseases.
What is Cyclostomata?
Cyclostomata. The Cyclostomata are the modified and degenerate offshoot of the primitive vertebrate stalk. Due to their circular mouth, they are named Cyclostomata. They are parasitic, usually feeding on fish in their adult stage. Morphologically, they resemble eels. They are known to be the only living vertebrates without true jaws,…
Why is a Cyclostomata called Agnatha?
Due to their circular mouth, they are named Cyclostomata. They are parasitic, usually feeding on fish in their adult stage. Morphologically, they resemble eels. They are known to be the only living vertebrates without true jaws, hence called Agnatha.
Why are eels called Cyclostomata?
Due to their circular mouth, they are named Cyclostomata. They are parasitic, usually feeding on fish in their adult stage. Morphologically, they resemble eels. They are known to be the only living vertebrates without true jaws, hence called Agnatha. Cyclostomata includes hagfishes and lampreys.
What are the two types of cyclostomes?
The cyclostomes are sub-divided into two major orders. Lampreys or lamper eels belong to this order. They are found in both marine and freshwater. They have a ventral mouth with many horny teeth. The nostril is present dorsally.