The Zuiyo-maru carcass is a creature initially claimed to be a prehistoric plesiosaur

Plesiosaur

Plesiosauroidea is an extinct clade of carnivorous plesiosaur marine reptiles. Plesiosauroids, are known from the Jurassic and Cretaceous Periods...

 that was caught by the Japanese fishing trawler off the coast of New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

 in 1977. Although several scientists insisted it was "not a fish, whale, or any other mammal", analysis later indicated it was most likely the carcass of a basking shark

Basking shark

The basking shark is the second largest living fish, after the whale shark. It is a cosmopolitan migratory species, found in all the world's temperate oceans. It is a slow moving and generally harmless filter feeder and has anatomical adaptations to filter feeding, such as a greatly enlarged...

 by comparing the number of sets of amino acids in the muscle tissue.

Decomposing basking shark carcasses lose most of the lower head area and the dorsal and caudal fins first, making them resemble a plesiosaur.

Discovery

On April 25, 1977, the Japanese trawler Zuiyō Maru, sailing east of Christchurch

Christchurch

Christchurch is the largest city in the South Island of New Zealand, and the country's second-largest urban area after Auckland. It lies one third of the way down the South Island's east coast, just north of Banks Peninsula which itself, since 2006, lies within the formal limits of...

, New Zealand, caught a strange, unknown creature in the trawl. The crew was convinced it was an unidentified animal (Bord, 1990), but despite the potential biological significance of the curious discovery, the captain, Akira Tanaka, decided to dump the carcass into the ocean again so not to risk spoiling the caught fish. However, before that, some photos and sketches were taken of the creature, nicknamed "Nessie

NESSIE

NESSIE was a European research project funded from 2000–2003 to identify secure cryptographic primitives. The project was comparable to the NIST AES process and the Japanese Government-sponsored CRYPTREC project, but with notable differences from both...

" by the crew, measurements were taken and some samples of skeleton, skin and fins were collected for further analysis by experts in Japan. The discovery resulted in immense commotion and a "plesiosaur-craze" in Japan, and the shipping company ordered all its boats to try to relocate the dumped corpse again, but with no apparent success. (Sjögren, 1980).

Description

The foul-smelling, decomposing corpse reportedly weighed 1,800 kg and was about 10 m long. According to the crew, the creature had a one and a half meter long neck, four large, reddish fins and a tail about two meters long. It lacked a dorsal fin. No internal organs remained, but flesh and fat was somewhat intact (Sjögren, 1980 and Welfare & Fairley, 1981).

Plesiosaur

Professor Tokio Shimaka from Yokohama University was convinced that the remains were of a supposedly extinct plesiosaur. Dr. Fujiro Yasuda from Tokyo University agreed with Shimaka that "the photographs show the remains of a prehistoric animal" (Sjögren, 1980).

However, other scientists were more skeptical. According to Bengt Sjögren (1980), the Swedish paleontologist Hans-Christian Bjerring was soon interviewed by Swedish news agency Tidningarnas Telegrambyrå

Tidningarnas Telegrambyrå

Tidningarnas Telegrambyrå – The Newspapers' Telegram Bureau – is a Swedish news agency, the largest in Scandinavia, owned jointly by the country's newspapers and the media groups behind them. TT's services are used as the exclusive source of national news by many local media outlets...

, and said:

"If it's true that the Japanese collected samples of fins and skin, it would be possible to conclude from a microscope

Microscope

A microscope is an instrument used to see objects that are too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy...

 what it is. If it would be shown to be a hitherto unknown animal from the sea, it is as big of a sensation as the discovery of the coelacanth

Coelacanth

Coelacanths are members of an order of fish that includes the oldest living lineage of Sarcopterygii known to date....

 in 1938... but there is reason to be suspicious of the claims of plesiosaurs, for example, as the marine environment and fauna changed drastically since the age of the plesiosaurs on earth."

Another Swedish scientist, Ove Persson, was also critical of the plesiosaur interpretation. He recalled other discoveries of similar dead marine creatures resembling plesiosaurs that on closer inspection revealed them to be just decomposed, unusually large shark

Shark

Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....

s. He also added, according to Sjögren (1980), "The discovery of the coelacanth was not as strange as if a plesiosaur would be discovered. The plesiosaur is much bigger and breathes with lungs. It seems incredible that it would manage to remain hidden."

Basking shark

On July 28, 1977, the Zuiyō Maru carcass was commented upon in the international science magazine New Scientist

New Scientist

New Scientist is a weekly non-peer-reviewed English-language international science magazine, which since 1996 has also run a website, covering recent developments in science and technology for a general audience. Founded in 1956, it is published by Reed Business Information Ltd, a subsidiary of...

. A scientist from the Natural History Museum

Natural History Museum

The Natural History Museum is one of three large museums on Exhibition Road, South Kensington, London, England . Its main frontage is on Cromwell Road...

 in London

London

London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

 had the same opinion as Bjerring and Persson: that the remains were not from a plesiosaur. The decomposition pattern of a basking shark, whose spine and brain case is relatively highly calcified for a cartilaginous fish, can be expected to produce a similar shape to a plesiosaur; the first parts that fall off during decomposition

Decomposition

Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...

 are the lower jaw, the gill area, and the dorsal and caudal fins. Bengt Sjögren (1980) concluded, "it was the infamous old ´Stronsay Beast

Stronsay Beast

The Stronsay beast was a large, dead carcass or globster that washed ashore on the island of Stronsay , in the Orkney Islands, after a storm on September 25, 1808...

´ that once again haunted like on innumerable other occasions. The scholars in Japan went into the same easy trap as the Scot

Scot

A Scot is a member of an ethnic group indigenous to Scotland, derived from the Latin name of Irish raiders, the Scoti.Scot may also refer to:People with the given name Scot:* Scot Brantley , American football linebacker...

naturalists did in the 19th century."