A hemocyanin from the Onychophora and the emergence of respiratory proteins

Kristina Kusche, Hilke Ruhberg, Thorsten Burmester*

*Corresponding author for this work
64 Citations (Scopus)


The velvet worms (Onychophora) are considered living fossils and are closely related to the Euarthropoda. Onychophora possess a tracheal system for respiratory function, but oxygen-transport proteins have been considered unnecessary. Here, we show that the hemolymph of the Epiperipatus sp. (Onychophora: Peripatidae) contains an arthropod-type hemocyanin, demonstrating that such protein exists outside the Euarthropoda. Thus, the evolution of oxygen carriers preceded the divergence of the Onychophora and Euarthropoda and was most likely linked to the evolution of an efficient circulatory system in a low-oxygen environment. The cDNA of the Epiperipatus hemocyanin subunit comprises 2,287 bp and encodes for a protein of 641 aa (73.6 kDa). Phylogenetic analyses of the arthropod hemocyanin sequences show that the Onychophora form a robust sister-group of the Euarthropoda, whereas the monophyly of the Tracheata is not supported.

Original languageEnglish
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number16
Pages (from-to)10545-10548
Number of pages4
Publication statusPublished - 08.2002


Dive into the research topics of 'A hemocyanin from the Onychophora and the emergence of respiratory proteins'. Together they form a unique fingerprint.

Cite this