What are 2 examples of the Chondrosteans?

What are 2 examples of the Chondrosteans?

Chondrosteans make up one of the three major subdivisions of the superclass Actinopterygii, the other two being the holosteans and the teleosts. The only living representatives are the sturgeons (family Acipenseridae) and paddlefishes (family Polyodontidae) in the order Acipenseriformes.

Are Chondrostei extinct?

Chondrosteiformes. Chondrosteiformes, an extinct order of ray-finned saltwater fishes (class Actinopterygii) comprising a single family Chondrosteidae.

Are clownfish teleosts?

There are several different mating systems among teleosts. This is rare among teleosts, and fish in general, but is found in the clownfish. In addition, it may also exist to an extent among anglerfish, where some females have more than one male attached to them.

Why Chondrostei are classified under Osteichthyes?

Taxonomy. This group has at times been classified with the sharks because the chondrosteans, like the latter, mostly lack bone, and their structure of the jaw is more akin to that of sharks than of other bony fish; further, both groups lack scales (excluding the Polypteriforms).

Is a sturgeon a freshwater fish?

Most sturgeons are anadromous bottom-feeders, which migrate upstream to spawn, but spend most of their lives feeding in river deltas and estuaries. Some species inhabit freshwater environments exclusively, while others primarily inhabit marine environments near coastal areas, and are known to venture into open ocean.

Is a gar a Chondrostean?

Three major orders of this subclass (ray-finned bony fish) are in existence; the Chondrostei (paddlefish, sturgeon); Holostei (gar, bowfin); and the Teleostei, which constitute the most advanced order and comprise the vast majority of present-day fishes; the number of nonteleost species of bony fish is very limited.

Why are teleosts so successful?

Numerous ideas have been put forward to explain teleost success, including the flexible structure of their jaws, a diversity of reproductive strategies and the symmetry of their tail fins.

Are perch teleosts?

Some teleosts—such as certain of the perchlike African cichlids, some catfishes, and some marine fishes (such as cardinal fishes)— are oral brooders, the male or female incubating the eggs in its mouth.

What scales are present in Osteichthyes?

The three categories of scales for Osteichthyes which are cosmoid scales, ganoid scales, teleost scales. The teleost scales are also then divided into two subgroups which are the cycloid scales, and the ctenoid scales.

Why is sturgeon fishing illegal?

In 2006 the green sturgeon was listed as threatened under the federal Endangered Species Act, making it off-limits for recreational fishing. California’s fish and wildlife department notes that while the white sturgeon is not yet listed, its survival is considered “conservation dependent.” So recreational fishing of …

Is it illegal to catch sturgeon?

Sturgeon are the largest freshwater fish in North America; they can grow to be over 1000 pounds and they can live 100 years or more. California is home to both white and green sturgeon though it is illegal to catch and keep the green species.

Are gars Teleosts?

Holosteans share with other non-teleost ray-finned fish a mixture of characteristics of teleosts and sharks. The gars have thick ganoid scales typical of sturgeons whereas the bowfin has thin bony scales like the teleosts. The gars are therefore in this regard considered more primitive than the bowfin.

What is another name for Chondrostei?

See Article History. Alternative Title: Chondrostei. Chondrostean, (subclass Chondrostei), any member of a group of primitive ray-finned bony fishes that make up one of the three major subdivisions of the superclass Actinopterygii, the other two being the holosteans and the teleosts.

Is Chondrostei a type of teleost?

Nevertheless, the fossil record suggests they have more in common with the teleosts. Chondrostei is probably a paraphyletic grouping, representing the primary radiation of bony fishes.

Is the subclass Chondrostei a paraphyletic group?

Many taxonomists argue that the subclass Chondrostei is a paraphyletic group—that is, a taxonomic group that does not include all descendants of a common ancestor. Living chondrosteans can grow quite large.

Are Chondrostei cartilaginous or ossified?

Chondrostei are primarily cartilaginous fish showing some degree of ossification. It is thought that the cartilaginous condition is derived, and that the ancestors of this group were bony fish with fully ossified skeletons.