Zuiyō-maru creature

The Zuiyō-maru creature (ニューネッシー Nyū Nesshii, lit. "New Nessie"), or the Zuiyō-maru carcass, was the name given to a carcass discovered by the crew of the Japanese fishing trawler Zuiyō-maru (瑞洋丸) off the coast of New Zealand in 1977. While initially taken to be the carcass of an extinct plesiosaur, subsequent chemical testing on parts of the remains kept by the crew, pictures taken of the carcass,and knowledge of animal decomposition definitively identified it as a basking shark carcass.

Discovery
On April 25 1977, around 30 km east from Christchurch, New Zealand, the Japanese trawler Zuiyō-maru dredged up a large animal carcass from a depth of around 300 metres (328 yards). Michihiko Yano (道彦矢野), a section chief for the Taiyo Fishery Company as well as a qualified biologist, was present and took photographs and measurements of the cryptid, as well as sketched it. Unfortunately, the carcass was subsequently hauled overboard as it was feared that it could have contaminated the entire catch of fish.

Description
The carcass measured approximately 10 metres (32 ft) in length and weighed around 1800 kg (4000 lb). The Zuiyō-maru carcass also possessed yellow fibres protruding from the front right flipper which could be extracted by hand. It also allegedly possessed a long, serpentine neck; however, this was a result of decomposition. There were also several lines of red flesh and fat running down the carcass' spine in uniform. Also on the back, there was a displaced dorsal fin.

While the carcass doesn't look much like a basking shark at first, this is due to the changes a dead shark undergoes decomposition. For example what appears to be a long neck is actually the shark's head and spinal cord, which are far slower to rot whereas the face and jaws rot and fall out relatively quickly. What looks like a small head with eye sockets at the end is actually the tip of the shark's face and nostrils. The remnants of the lower jaw can be seen as the Y shaped body part laying against the chest.

Identification
Several muscle tissue samples taken from the Zuiyō-maru creature were sent to Tokyo University for testing. Analysis of the specimens strongly indicated that the creature was a decomposing basking shark (Cetorhinus maximus) as they had detected the presence of elastoidin, a protein found exclusively in sharks and rays. Despite claims to the contrary, this classification was very definitive as the creature even had a cartilaginous skeleton, unlike the bony skeleton all tetrapods such as plesiosaurs had.

Basking shark elastoidin samples were treated with a sodium hypochlorite (NaClO) solution, which acted as an antiseptic, and compared to treated elastoidin from the carcass. The results were practically identical; the high amounts of tyrosine amino acids found in both tissue samples were noted as a quintessential property of shark elastoidin.