If you’ve been waiting for a strange, maybe even horrifying, story that can’t be blamed on the year 2020 – here it is. Unfortunately, there’s a long line of other years to blame it on. Marine biologists studying a mysterious skinless, toothless shark caught off the coast of Sardinia in 2019 (in your face, 2020) have finally identified it as a healthy first-of-its-kind (read between the lines – that’s a warning) toothless, skinless blackmouth catshark. How did it get that way and why do they think we’ll see more of them?
“As far as is known, in this paper the first case of lacking of skin‐related structures (epidermis, stratum laxum, dermal denticles and teeth) in a free‐swimming elasmobranch, the blackmouth catshark, Galeus melastomus, is reported. The individual was caught by trawl in Sardinian waters (central‐western Mediterranean) in July 2019 at a depth of 500 m. Although this kind of morphological abnormality is potentially fatal, the observations suggested that the specimen was in good health and well developed.”
A normal blackmouth catshark
In a paper published in the Journal of Fish Biology titled ‘Living naked: first case of lack of skin‐related structures in an elasmobranch, the blackmouth catshark (Galeus melastomus)’, researchers led by Antonello Mulas at the Department of Life and Environmental Sciences, University of Cagliari, Italy, studied a single specimen caught by a fishing trawler in the Mediterranean Sea near Sardinia in 2019. (Photos here.) The specimen was alive when it was caught and appeared to be in good shape – except for the lack of skin and teeth. When opened, the contents of the stomach of the soon-identified blackmouth catshark – a small shark species native to the Mediterranean and the Atlantic – were whole fish, indicating it ate well without the benefits of teeth to catch or cut up prey. The lack of skin was another story.
“Elasmobranch skin represents a fundamental organ responsible for multiple functions, due to both the properties of its cellular layers and the peculiar characteristics of the tooth-like dermal denticles. The mucus secreted by the columnar-like secretory cells of the epidermis layer is considered the first part of the immune system, as it prevents the colonization of infectious microbes through different mechanisms, such as its continuous production and removal and by containing antibacterial proteins.”
Theinetia.com quotes the study’s assessment of what problems being “naked” caused this female shark. In addition to it not having protection against the environment and some camouflage against predators and prey – this one was a solid pale yellow instead of a normal spotted brown-and-white – the skinless blackmouth catshark probably swam funny too … perhaps it was cold or scared or both. In any case, that’s not what caused it to lose its skin or its teeth … nor its life.
A normal toothed black mouth of a blackmouth catshark
“Researchers are baffled at both how the shark managed to survive without skin and teeth, but they’ve theorized that it could have something to do with long-term exposure to some sort of contaminated part of the ocean, ocean warming, or simply be a genetic hiccup.”
Pollution, climate change or a genetic mutation caused by … pollution and climate change. What a shock. The researchers plan to continue studying this toothless, skinless blackmouth catshark in hopes of making this first-of-its-kind the only one of its kind.
What do you think the chances are of THAT happening?
from Mysterious Universe https://ift.tt/3hzsIVd
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