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Megalodon nurseries reveal world’s largest shark had a soft side

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The enormous, extinct shark Megalodon probably doesn’t make you think of parenting and playdates. But a growing body of evidence suggests that these massive marine predators nurtured their babies by raising them in nurseries, and scientists just added five potential Megalodon nurseries to the list. 



a bird flying over a body of water: Megalodon, the biggest predatory shark of all time, watched over its young as many modern sharks do — by raising them in defined geographic areas known as nurseries.

© Provided by Live Science
Megalodon, the biggest predatory shark of all time, watched over its young as many modern sharks do — by raising them in defined geographic areas known as nurseries.

These baby-shark grounds are showing up all over. Scientists reported in 2010 that they had identified a Megalodon nursery in Panama. Recently, another team of researchers described a new Megalodon nursery site in northeastern Spain; fossils of fully grown sharks and youngsters were found together, with most of the fossils belonging to juveniles and newborns. 

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Those same scientists also analyzed data from eight other sites — from 16 million to 3 million years ago — where Otodus megalodon fossils were plentiful. They evaluated the body sizes of individual sharks to determine the ratio of juveniles to adults, and named four additional nursery sites. 

The results suggest that Megalodon adults commonly raised their young in nursery areas, where the wee shark babies would be protected until they were able to fend for themselves against other ocean predators. It also raises the possibility that the decline of available nursery sites may have contributed to the giant shark’s extinction, according to a new study.

Related: Photos: These animals used to be giants

O. megalodon is estimated to have measured up to 50 feet (15 meters) in length, making it the biggest predatory shark that ever lived. Most Megalodon fossils date to about 15 million years ago, and the giant fish vanished from the fossil record about 2.6 million years ago.

Today, many modern sharks raise their young in nurseries. Waters near northern Patagonia’s Buenos Aires province hold a nursery for several shark species, and a nursery of sand tiger sharks (Carcharias taurus) in Long Island’s Great South Bay hosts juvenile sharks that live there until they are 4 or 5 years old. And the oldest known shark nursery is more than 200 million years old, according to fossilized egg cases found alongside shark “baby teeth” that are just 0.04 inches (1 millimeter) long, Live Science previously reported.

For the new study, the researchers investigated 25 teeth belonging to O. megalodon  from the Reverté and Vidal quarries in Spain’s Tarragona province. They used tooth crown height to estimate body size and to identify which of the sharks were babies; very young sharks — likely about one month old — that measured about 13 feet (4 m) long, and older juveniles measured up to 36 feet (11 m) in length. 

The scientists then used algorithms to model and compare the ratio of O. megalodon juveniles to adults at eight other sites across “a wide geographical area” that included the Atlantic, Caribbean and Pacific basins. They determined five potential nurseries “with higher densities of

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Shark Stabbed Through the Heart, Swordfish to Blame | Smart News

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This past April, a trio of citizen scientists made a strange discovery on a beach in Libya. They spied the 14.5-foot body of a dead thresher shark sloshing in the tide and, upon closer inspection, saw something strange: what turned out to be a swordfish bill sticking out of a deep, penetrating wound between the creature’s head and dorsal fin.

A study detailing this instance of apparent undersea swashbuckling, published this month in the journal Ichthyological Research, is the latest confirmed report of swordfish stabbing sharks to death, reports Melissa Cristina Marquez for Forbes. The idea that swordfish might use their bills to impale their enemies or their prey used to be the conventional wisdom among fishers, whalers and even academics, writes Joshua Sokol for the New York Times, but “modern scientists were skeptical.”

The common explanation for a swordfish’s bill ending up buried in some other denizen of the sea was essentially that they were trying to swipe or stab smaller prey and missed, instead ramming into whales, sea turtles, boats and even submarines, per the Times. The paper’s authors are quick to note that they can’t rule out that this thresher shark’s death was the result of an unhappy accident, but, according to the Times, there have been at least six other documented cases of swordfish mortally wounding sharks elsewhere in the Mediterranean.

What makes the idea of these deep-sea stabbings being complete accidents a bit harder to fathom is their precision. In the case of this large thresher in Libya, the female shark was lanced straight through the heart, and a blue shark found in 2016 off the coast of Spain had been stabbed in the brain.

The researchers behind the current study came upon their subject when one of them encountered a video posted by one of the citizen scientists who first found the dead shark on the Libyan coast. The case of this dead thresher shark piqued the scientists’ interest because an adult swordfish inflicted the wound.

“We knew of juvenile swordfish who attacked blue sharks in order to defend themselves, however in this case a rather harmless (at least, harmless for the swordfish) thresher shark was attacked by an adult swordfish,” Patrick L. Jambura, a shark researcher at the University of Vienna and the study’s lead author, tells Forbes.

Threshers aren’t known to prey on adult swordfish, so Jambura and his co-authors argue that the stabbing could have been a case of two deep sea predators fighting over a meal or territory.

It’s impossible to infer exactly what occurred in the inky fathoms, but Jambura thinks this “shows how aggressive swordfish” can be and that because the two fish were adults of similar size that we can “exclude a defensive behavior as the trigger for this attack,” he tells Forbes. “It either happened in the heat of the moment, when both species were hunting on the same prey resource (schooling fish or squid) or it might have

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Great White May Be Leading Scientists to a Shark Nursery, As 15-foot Predator Located Off Bahamas

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A 15-foot-long great white shark has been tracked to near the Bahamas and researchers believe the female could soon reveal the site of a great white shark nursery.

The shark, known as Unama’ki, is being tracked by research non-profit OCEARCH, who monitor hundreds of marine animals—ranging in size from whales to turtles—around the globe.

“When we first met Unama’ki, we knew she had the potential to lead us to a site where she might give birth. Today on the #OCEARCH Global #SharkTracker she’s in the Bahamas, roughly 50 miles northeast of Guana Cay on the edge of the Blake escarpment,” the non-profit said in a Tweet on Friday.

OCEARCH researchers first captured and tagged Unama’ki—who weighs around 2,000 pounds—in September, 2019 off the coast of Cape Breton in Nova Scotia, Canada.

Since then, the shark has traveled more than 12,500 miles, having swum almost the entire length of the North American east coast, entering the Gulf of Mexico, heading out deep into the Atlantic Ocean and reaching as far north as Newfoundland before finally heading south towards the Bahamas, near where she was located on October 29.

Researchers said it was “curious” that Unama’ki was making a similar journey to that previously made by two other large, mature, female, white sharks, known as Luna and Lydia.

“Could she be pregnant, and moving into a calmer area?” OCEARCH asked on Twitter. “We’re hoping she exposes a new #greatwhiteshark nursery to us next spring or summer.”

Another shark, known as Mary Lee, was previously tracked making a long journey into the open ocean before returning to shore near Long Island, where a white shark nursery has been found, OCEARCH Founding Chairman and Expedition Leader Chris Fischer previously told Newsweek.

OCEARCH researchers locate sharks using SPOT (Smart Position and Temperature) tags, which are mounted on the top of the shark’s first dorsal fin. Scientists receive an alert, known as a “ping”, when a tracking satellite overhead detects the fin breaking the surface of the water.

In addition to SPOT tags, OCEARCH researchers also try and fit sharks with both an acoustic tag and a Pop-off Archival Satellite Tag (PSAT.)

Acoustic tags record a shark’s location by communicating with receivers stationed on the bottom of the ocean, while PSATs collect data on depth, temperature and light levels, automatically detaching from the animal at one point between six months and a year.

Collecting this type of data while also taking biological samples from the sharks they capture, provides OCEARCH researchers with valuable new insights to these powerful marine predators.

great white shark Unama'ki
The great white shark Unama’ki aboard the OCEARCH research vessel.
OCEARCH/R. Snow

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Egg-Cellent Find For Shark Relatives

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There are over 1,000 species of cartilaginous fish roaming in our oceans. These fish include sharks and their relatives, the batoid fishes (including skates, rays, guitarfishes, and sawfishes) and chimaeras. Skates and rays are often known as #flatsharks on social media since both animals are usually flat and sport a long tail.

One of these species is the flapper or common skate (Dipturus intermedius), previously considered part of the Dipturus batis species complex. They are the largest member of the family Rajidae found in Europe and once had a widespread range but is now classified as Critically Endangered by the International Union for Conservation of Nature (IUCN) due to their low intrinsic population growth rate and sensitivity to overfishing. Although flapper skates were effectively extirpated across much of their historical range, small populations have persisted in these European shelf waters. One of these areas is along the western and northern coasts of Scotland which is where marine biologist Dr. Lauren Smith and her team recently discovered over a hundred egg cases belonging to these vulnerable animals.

Volunteer divers and scientists, with the help of local scallop divers, found the so-called mermaid purses nestled between rocks for protection. Measuring over 25 cm long and taking almost 18 months to hatch, the observers noticed the egg cases were of different sizes and ages, indicating that the site is probably used by a resident population of this endangered skate and probably has been for multiple years. “This is the biggest and most important egg laying site discovered to date,” explained Smith. “Unfortunately, both the purses themselves and the newly hatched young are so large that they can be caught in bottom towed gear and destroyed – a single pass with a dredge could obliterate the site!”

The discovery comes almost a year after the research team recorded egg cases at the same site in November 2019 and reported the findings to Marine Scotland since the flapper skate is one of 81 Priority Marine Features the Scottish Government is committed to protecting. However, according to Smith, no action has been taken by Marine Scotland to protect this site. Fortunately, other conservation measures have been put in place such as it being illegal for fishers to commercially target the flapper skates since 2009. But even this can’t protect them from being captured as bycatch from multiple fisheries.

Capable of reaching over 8.2 feet (2.5 meters) in length, this animal is at greater risk of extinction than the mountain gorilla or the

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Swordfish Vs Shark: What The Heck?!

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Slash!

A swordfish (Xiphias gladius) uses its bill in a duel between another top predator: a shark. It sounds like an unlikely match, but this highly mobile, predatory fish has been recorded to attack sharks since the early 1960’s! And while sharks are covered in dermal denticles, which provide some degree of protection, it seems it is no match against the swordfish bill… or so suggests the thresher with one embedded in its body.

In April 2020, a dead female thresher shark (family Alopiidae) was found washed ashore on the Libyan coast near the town of Brega. At first, the shark didn’t seem to have any external injuries, but after a quick examination the researchers found a single penetrating trauma with the tip of the swordfish bill stuck in it. Aggressive behaviour towards thresher sharks was only suggested in a conference contribution, but the stranded bigeye thresher (Alopias superciliosus) was the first verified illustrated documentation of one being fatally wounded by a swordfish. “It was [shock]. We knew of juvenile swordfish who attacked blue sharks in order to defend themselves, however in this case a rather harmless (at least, harmless for the swordfish) thresher shark was attacked by an adult swordfish,” said lead author of the study Patrick L. Jambura of the Department of Palaeontology at the University of Vienna. “This left us quite puzzled for the first moment, but this feeling quickly turned into excitement when we realised that we got an unique opportunity to work on this unusual sight!”

Like other thresher sharks, the bigeye has the long tail that has made this family so easy to identify. Stunning small fish and squid with their tail, this species are known to spend most of their time in the deep where their big eyes help to see in the low light conditions. A cosmopolitan species, they are considered as pesky bycatch of the swordfish longline fishery off the United States of America. Afterall, swordfish are highly valued as a commercial species and recreational species. As adults, the swordfish can grow up to 14.75 feet (4.5 meters) long which can fetch a pretty penny depending the buyer. Like sharks, swordfish are endothermic and have the ability to maintain body temperatures above that of the surrounding water, allowing them to hunt pelagic fishes such as tuna, flying fish, barracudas, squid, cuttlefish, and more. Since adult swordfish lack teeth, they are thought to slash or stun their prey before swallowing it whole.

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Rare Two-Headed Shark Found By Fisherman, Photos Go Viral

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A rare baby shark with two heads was discovered by a fisherman off Palghar coast in the Indian state of Maharashtra last week.

The fisherman, identified as Nitin Patil, threw the six-inch shark back into the sea after taking a few photos of it.

“We do not eat such small fish, especially sharks, so I thought it was strange but decided to throw it anyway,” Patil told local daily the Hindustan Times.

He then showed the photos to other fishermen who told him that it was a rare anomaly. The fishermen in turn shared the photos with researchers from the Indian Council for Agricultural Research – Central Marine Fisheries Research Institute (ICAR-CMFRI).

The researchers confirmed that the discovery was a very rare documentation.

“Our records show that double-headed sharks are very rarely reported along the Indian coast. This species appears to be the embryo of the spadenose shark (Scoliodon laticaudus) from the Carcharhinidae family or a sharpnose shark (Rhizoprionodon species). Both are viviparous and are common in Maharashtra waters,” said Dr. Akhilesh KV, scientist at ICAR-CMFRI, told the newspaper.

He went on to say that the heads of the shark were joined behind the gills.

“These are also called dicephaly. This phenomenon is reported in several animal species including sharks, possibly due to mutation or any other embryonic malformation, disorders, and these are very rare reports. Similar cases are reported elsewhere outside the northern Indian Ocean. These materials should be preserved out of scientific interest,” he added.

However, another researcher told the newspaper that the species have a very low survival rate.

“There are hardly any documentations of this species as adults. This finding is purely an aberration. We cannot attribute it to any exact reason. It is regularly seen for snake species or conjoined or Siamese twins in humans. In maximum cases, they do not survive beyond the juvenile stage, but it definitely opens up an avenue for much needed research,” E Vivekanandan, emeritus scientist, ICAR-CMFRI told the newspaper.

whitetip-reef-shark-586362_640 shark Photo: Pixabay

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