láncszálak

Láncszálak, also known as lancelets or amphioxus, are small, marine invertebrate chordates belonging to the subphylum Cephalochordata. They are considered to be among the closest living relatives to vertebrates. Láncszálak possess a segmented body, a notochord that extends the length of the body, and a dorsal nerve cord. These features are characteristic of the phylum Chordata, which also includes vertebrates.

These creatures typically inhabit sandy or muddy bottoms in shallow, temperate, and tropical seas. They are filter feeders, using a ciliated buccal cavity to draw water and food particles into their bodies. Their lifestyle is largely sedentary, often burying themselves partially in the substrate with only their anterior end exposed for feeding.

The anatomy of láncszálak is remarkably simple yet exhibits key chordate features that have made them important subjects in evolutionary biology research. Their transparent bodies allow for easy observation of internal structures. Láncszálak lack a true head with a complex brain, but they do have an anterior end with a rudimentary sensory structure. Their life cycle involves a planktonic larval stage before settling to the seabed. The study of láncszálak provides valuable insights into the evolutionary origins of vertebrates.