Great news! After months of rebuilding/repair, we are extremely happy to announce that Desktop Nexus is back!
There were a few images that were unrecoverable, but over 99% of the missing photos are now fully restored!
Thank you so much for your patience, we really appreciate it! You guys are the best community on earth! [hide]
The structure of the heart can vary among the different branches of the animal kingdom. (See Circulatory system.) Cephalopods have two "gill hearts" and one "systemic heart". In vertebrates, the heart lies in the anterior part of the body cavity, dorsal to the gut. It is always surrounded by a pericardium, which is usually a distinct structure, but may be continuous with the peritoneum in jawless and cartilaginous fish. Hagfishes, uniquely among vertebrates, also possess a second heart-like structure in the tail.