Cyclostome

Cyclostome is a term used in the field of biology to refer to a group of vertebrates that includes the lampreys and hagfishes. These creatures are characterized by their round, jawless mouths, which is where the term "cyclostome" (meaning "round mouth") comes from.

Characteristics

Cyclostomes are unique among vertebrates for their lack of jaws. Instead, they have round, sucker-like mouths that they use to attach to other fish and suck out their bodily fluids. They also lack paired fins and have a notochord, which is a flexible rod that supports the body, instead of a true vertebral column.

Classification

Cyclostomes are classified in the superclass Agnatha, along with the extinct ostracoderms. However, some scientists argue that they should be placed in their own group, separate from the ostracoderms, due to their unique characteristics.

Evolution

The evolution of cyclostomes is a topic of ongoing debate among scientists. Some believe that they are the most primitive living vertebrates, while others argue that they are highly specialized and derived from jawed ancestors.

Species

There are about 100 species of cyclostomes, divided into two orders: the Petromyzontiformes, which includes the lampreys, and the Myxiniformes, which includes the hagfishes.

See also

• Vertebrate
• Agnatha
• Lamprey
• Hagfish

References

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