Showing posts with label Sleeper Sharks. Show all posts
Showing posts with label Sleeper Sharks. Show all posts

Monday, 11 April 2022

Greenland Shark found on Cornish beach died of Meningitis.

A Greenland Shark, Somniosus microcephalus, which was found stranded on a beach near Newlyn Harbour in Cornwall, England, in March 2022, has been found to have died of Meningitis. The Shark, which was spotted on the beach on 13 March and recovered by a recreational boating company two days later, after washing back out to sea, was subjected to a necropsy (the term 'autopsy' is only used when the subject is Human) by the Cornwall Marine Pathology Team, which discovered it had been suffering from an inflamation of the membrane surrounding the brain (Meningitis). Later analysis of tissue taken from this membrane found that it was infected with the Gammaproteobacterium Pasteurella, known to cause Meningitis but mostly associated with domestic Mammals and never before reported from a Greenland Shark.

 
A Greenland Shark, Somniosus microcephalus, washed up on a beach near Newlyn Harbour in Cornwall, in March 2022. Cornwall Marine Pathology Team.

The Shark was found to be a female, and is calculated to have been about 100 years old, and therefore considered to have been a juvenile in a species that is thought to be able to be able to live for over 400 years. Greenland Sharks are a coldwater Sleeper Shark species found in the Arctic and North Atlantic oceans. They are piscivores (Fish eaters) and never attack Humans (species of Shark which target Marine Mammals will sometimes attack Humans, though they usually spit us out), and for the most part are not consumed by Humans either, due to the high levels of trimethylamine oxides (which are both toxic and foul smelling) in their flesh, though in Iceland Greenland Shark meat detoxified by fermenting is eaten as a delicacy, kæstur hákarl.

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Wednesday, 5 June 2019

Icelandic fishermen fired for cruelty to Greenland Shark.

Two Icelandic fishermen have been fired after cutting the tail off a Greenland Shark, Somniosus microcephalus, throwing it back into the water, then posting film of themselves mocking the wounded animal onto Facebook. Halldór Gústaf Guðmundsson and Gunnar Þór Óðinsson were crew members on a Bíldseyar SH 65-owned vessel before the incident, but were quickly fired after an outcry on social media, with the company issuing a statement that it believed in 'good working practises and responsible handling of resources and the environment in general'. The men may also face criminal charges from authorities in Iceland or Denmark (the later because the incident happened in Danish territorial waters off the coast of Greenland). The Shark is thought to have no chance of surviving without its tail.

An injured Greenland Shark, Somniosus microcephalus, swimming away from an Icelandic fishing vessel after having it's tail removed. Facebook.

Greenland Sharks are a coldwater Sleeper Shark species found in the Arctic and North Atlantic oceans. They are piscivores (Fish eaters) and never attack Humans (species of Shark which target Marine Mammals will sometimes attack Humans, though they usually spit us out), and for the most part are not consumed by Humans either, due to the high levels of trimethylamine oxides (which are both toxic and foul smelling) in their flesh, though in Iceland Greenland Shark meat detoxified by fermenting is eaten as a delicacy, kæstur hákarl.

 A healthy Greenland Shark at a landslide debris field between Alvin and Nantucket Canyons, off the coast of New England, in August 2013. Okeanos Explorer/NOAA/Wikimedia Commons.

See also...

https://sciencythoughts.blogspot.com/2019/06/teenager-injured-by-shark-in-north.htmlhttps://sciencythoughts.blogspot.com/2019/06/sphyrna-mokarran-pregnant-great.html
https://sciencythoughts.blogspot.com/2019/05/californian-man-killed-by-shark-off.htmlhttps://sciencythoughts.blogspot.com/2019/05/diprosopovenator-hilperti-new-species.html
https://sciencythoughts.blogspot.com/2019/05/identifying-sharks-and-rays-from-waters.htmlhttps://sciencythoughts.blogspot.com/2018/12/carcharhinus-melanopterus-leucism-in.html
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Thursday, 16 January 2014

Deepwater Sharks from the Early Miocene of Slovakia.

Sharks appear in the fossil record between 450 and 420 million years ago (all possible specimens older than 420 million years old are fragmentary and disputed), and have been important marine (and in the Carboniferous and Permian, freshwater) predators ever since. They form an important part of the marine fossil record in many areas, and are occasionally used for stratigraphy (dating rocks), though often they are usually only represented by their teeth, which are mineralized and grown and shed throughout their lives, rather than their skeletons, which are comprised entirely of cartilage, and consequently have poor preservational potential.

In a paper published in the journal Acta Palaeontologica Polonica on 12 January 2012, Charles  Underwood of the Department of Earth and Planetary Science at Birkbeck College and Jan Schlogl of the Department of Geology and Paleontology at Comenius University describe a collection of deepwater Shark's teeth from the Cerová−Lieskové locality in the Malé Karpaty Mountains in Slovakia.  This is a claypit noted for a broad range of vertebrate and invertebrate fossils from the Early Miocene of the Central Paratethys Sea. These fossils are thought to be important, as while Shark teeth are well represented in the fossil record, deepwater Sharks are relatively poorly known.

Ten incomplete specimens are referred to the genus Galeus (Sawtooth Catsharks), though not assigned to any species. These are small specimens, the largest being about 0.7 mm. The genus Galeus first appears in the fossil record in the Early Miocene of France, and is widespread in the Atlantic and Pacific today.

Teeth assigned to the genus Galeus from the Early Miocene Cerová−Lieskové locality. (A) Anterolateral tooth in labial (A₁) and lingual (A₂) views. (B) Anterolateral tooth in labial view. (C) Posterior tooth in labial view. (D) Anterior tooth in labial view. (E) Anterolateral tooth in labial view. (F) Anterolateral tooth in labial view. Underwood & Schlogl (2012).

A single, 2.2 mm, broken tooth is assigned to the genus Squatina (Angel Sharks). Modern Angel Sharks are found globally in tropical and temperate seas; most species are restricted to shallow waters, though one species, the Sand Devil (Squatina dumeril) is known to migrate seasonally into deep water. Angle Sharks are flattened Sharks resembling Skates and Rays (to which they are not closely related) and living on the sea bottom. Angel Sharks are considered to belong to a separate order (Squaliformes) which first appears in the fossil record in the Late Jurassic, with members of the modern genus (Squatina) known from the Middle Cretaceous.

Partial tooth assigned to the genus Squatina from the Early Miocene Cerová−Lieskové locality. Underwood & Schlogl (2012).

Three oral and one incomplete rostral teeth (rostral teeth are projections on the side of the snout of a Sawshark or Sawfish) are referred to the genus Pristiophorus (Five-gilled Sawsharks), and assigned to a new species, Pristiophorus striatus. Sawsharks resemble Sawfish (which are also Sharks), but are found in deepwater, while the Sawfish are shallow-water dwellers. The two groups are not closely related, Sawfish being related to Skates and Rays (Batoidea).  The oldest Sawsharks appear in the Lart Cretaceous of the Lebanon, about 85 million years ago, modern Sawsharks are found in the Indian and Pacific Oceans as well as the Caribbean, though their fossil record suggests they were more widely distributed for much of the Tertiary. 

Teeth assigned to the species Pristiophorus striatus from the Early Miocene Cerová−Lieskové locality. (H) Lateral tooth in labial (H₁), occlusal (H₂), and basal (H₃) views. (I) Partial rostral tooth in lateral view. (J) Anterior tooth in labial (J₁), occlusal (J₂), and basal (J₃) views. (K) Lateral tooth in labial (K₁) and basal (K₂) views. Underwood & Schlogl (2012).

A large number (236) of teeth are assigned to the genus Squaliolus (Pygmy Sharks or Deep-sea Dogfish), and tentatively to the species Squaliolus schaubi, a species previously described from the Miocene of France. Modern Pygmy Sharks are small deepwater species with specialized organs that house bioluminescent bacteria. They are a form of Kitefin Shark (Dalatiidae), a group that first appear in the fossil record in the Early Cretaceous of Germany.


Teeth tentatively assigned to the species Squaliolus schaubi from the Early Miocene Cerová−Lieskové locality. (A) Lower tooth in labial (A₁) and lingual (A₂) views. (B) Lower tooth in labial (B₁) and lingual (B₂) views. (C) Lower posterior tooth in labial (C₁) and lingual (C₂) views. (D) Male lower tooth in labial view. (E) Lower symphyseal tooth in labial (E₁) and lingual (E₂) views. (F) Lower tooth in labial (F₁) and lingual (F₂) views. Upper tooth in labial (G₁) and lingual (G₂) views. (H) Upper tooth in labial (H₁) and lingual (H₂) views. (I) Upper tooth in labial (I₁) and lingual (I₂) views. (J) Upper tooth in labial view. (K) Upper tooth in labial (K₁) and lingual (K₂) views. (L) Upper posterior tooth in labial (L₁) and lingual (L₂) views. Underwood & Schlogl (2012).

Fourteen partial and complete teeth are referred to the genus Eosqualiolus, a genus of Kitefin Shark which previously contained only a single fossil species from the Eocene of France, and assigned to a new species, Eosqualiolus skrovinai, which is named after Michal Škrovina, described as the first person to encourage Jan Schlogl in to pursue an interest in palaeontology.

Teeth assigned to the species Eosqualiolus skrovinai from the Early Miocene Cerová−Lieskové locality. (A) Lower tooth in labial (A₁) and lingual (A₂) views. (B) Lower tooth in labial (B₁) and lingual (B₂) views. (C) Lower tooth in labial (C₁) and lingual (C₂) views. (D) Lower tooth in labial (D₁) and lingual (D₂) views. (E) Upper tooth in labial (E₁) and lingual (E₂) views. (F) Upper tooth in labial (F₁) and lingual (F₂) views. (G) Upper tooth in labial (G₁) and lingual (G₂) views. Underwood & Schlogl (2012).

One, damaged, tooth is assigned to a third Kitefin Shark genus, Squaliodalatias, though not assigned to a species due to its poor condition. Fossils assigned to this genus have previously been found from the Late Cretaceous of Lithuania and the Eocene of France.

Tooth assigned to the genus Squaliodalatias from the Early Miocene Cerová−Lieskové locality. In labial (H₁) and lingual (H₂) views. Underwood & Schlogl (2012).

Eight partial and complete teeth are assigned to the genus Etmopterus (Lantern Sharks in the family Etmopteridae), small, deepwater Sharks with light producing organs, found more-or-less globally today. The earliest known Lantern Sharks are from the Eocene of France.

Teeth assigned to the genus Etmopterus from the Early Miocene Cerová−Lieskové locality. (A) Lower tooth in labial (A₁) and lingual (A₂) views. (B) Lower tooth in labial (B₁) and lingual (B₂) views. (C) Lower posterior tooth in labial (C₁) and lingual (C₂) views. (D) Lower tooth in labial (A₁) and lingual (A₂) views. (E) Lower tooth in labial (E₁) and lingual (E₂) views. (F) Lower tooth in labial view. (G) Upper tooth in labial (G₁) and lingual (G₂) views. Underwood & Schlogl (2012).

Ten partial and complete teeth are tentatively assigned to the genus Miroscyllium (Rasptooth Dogfish), a second type of Lantern Shark. The genus is previously known from a single modern species from the Pacific and some teeth from the Eocene of France.

Teeth tentatively assigned to the genus Miroscyllium from the Early Miocene Cerová−Lieskové locality. (H) Lower symphyseal tooth in labial (H₁) and lingual (H₂) views. (I) Lower tooth in labial (I₁) and lingual (I₂) views. (J) Lower lateral tooth in labial (J₁) and lingual (J₂) views. (K) Lower tooth in labial (K₁) and lingual (K₂) views. Underwood & Schlogl (2012).

Fifty three partial and complete teeth are assigned to the genus Paraetmopterus, an extinct Lantern Shark previously only known from teeth from the Eocene of France, and placed in a new species, Paraetmopterus horvathi, named in honour of Juraj and Tereza Horvath and their children.

Teeth assigned to the species Paraetmopterus horvathi from the Early Miocene Cerová−Lieskové locality. (A) Lower tooth in labial (A₁) and lingual (A₂) views. (B) Lower tooth in labial (B₁)
and lingual (B₂) views. (C) Lower tooth in labial (C₁) and lingual (C₂) views. (D) Lower tooth in labial (D₁) and lingual (D₂) views. (E) Lower tooth in labial (E₁) and lingual (E₂) views. (F) Lower tooth in labial (F₁) and lingual (F₂) views. (G) Upper anterior tooth in labial (G₁) and lingual (G₂) views. (H) Upper tooth in labial (H₁) and lingual (H₂) views. (I) Upper tooth in labial (I₁) and lingual (I₂) views. (J) Upper tooth in labial (J₁) and lingual (J₂) views. Underwood & Schlogl (2012).

A single tooth is assigned to the family Somniosidae (Sleeper Sharks), a widespread group of Sharks that first appear in the fossil record in the Late Cretaceous of Germany.

Tooth assigned to the family Somniosidae from the Early Miocene Cerová−Lieskové locality. In labial (K₁) and lingual (K₂) views. Underwood & Schlogl (2012).

A single imperfect tooth is referred to the genus Gymnura (Butterfly Rays). Modern Butterfly Rays are typically shallow water species, often found in brackish estuarine waters. The genus has a sparse fossil record, but is known from the Palaeocene of India, spreading around Europe, the Middle East and Africa in the Eocene and reaching the Americas in the Oligocene.

Tooth assigned to the genus Gymnura from the Early Miocene Cerová−Lieskové locality. In occlusal (I₁) and basal (I₂) views. Underwood & Schlogl (2012).

Twenty eight complete and partial teeth are assigned to a new species, Nanocetorhinus tuberculatus, of uncertain affinities, but considered to probably be a Neoselachian (the group that includes all extant Sharks, Skates and Rays). The genus name Nanocetorhinus refers to the similarity of the teeth to those of the planktivorous Shark Cetorhinus (the Basking Shark), though these teeth are much smaller, and the specific name, tuberculatus refers to the ornamentation on the teeth.

Teeth assigned to the species Nanocetorhinus tuberculatus from the Early Miocene Cerová−Lieskové locality. (A) Tooth in labial (A₁) and lingual (A₂) views. (B) Tooth in labial (B₁) and lingual (B₂) views. (C) Tooth in labial (C₁) and lingual (C₂) views. (D) Tooth in labial (D₁) and lingual (D₂) views. (E) Tooth in labial (E₁) and lingual (E₂) views. (F) Tooth in labial (F₁) and lateral (F₂) views. (G) Tooth in labial (G₁) and lingual (G₂) views. (H) Tooth in labial (H₁) and lingual (H₂) views, detail (H₃). Underwood & Schlogl (2012).

While the majority of these Sharks belong either to extant genera or extant families, the assemblage is on the whole closer to the deepwater Sharks of the Eocene than to modern Shark assemblages, suggesting that there has been more turnover in deepwater Shark populations since the Miocene than between the Eocene and the Miocene. One remarkable feature of this assemblage is the small size of all the Sharks present; based upon the available material Underwood & Shlogl estimate that none of the Sharks were more than 40 cm in length, though they do not offer any hypothesis as to why this was the case.