Marine Wildlife

Marine Wildlife (28)

 

The East London aquarium is an interesting little aquarium with daily fish feeding, fun and informative thanks to a number of unique displays and features including a whale-watching deck, a breeding colony of African penguins and an exciting seal shows.

Penguins at the east London Aquarium

The aquarium has some beautiful large fish tank displays that feature most of the local fish population. The lighting of these tanks add to the experience of visiting this small but well planned and maintained establishment.

East London aquarium Tanks

All around this Aquarium is boards with well researched information about South African marine life.

Information Boards East London aquarium

There is a colony of African penguins, sea-turtles, seals, a variety of marine fish and seabirds. Unique to this Eastern Cape aquarium is the display housing three Cape pygmy clawed lobsters.

Sea-turtle

This aquarium also serves as a haven for injured, oiled and distressed marine creatures washed up on East London’s beaches, which total a few hundred seabirds, turtles and dolphins that are treated, rehabilitated and released every year.

Oil birds East London aquarium

The Southern Right whales migrate annually down the coast of South Africa to their arctic feeding grounds and come close inshore at East London and with this in the mind the aquarium built an eleven meter high platform that sits right above the surf and provides an excellent opportunity to watch these magnificent animals breaching in the bay. This is build just above the pool where a couple of seals are staying.

Cape Fur Seals - East London

The East London Aquarium is South Africa’s oldest aquarium, and opened it’s doors in 1931, a must-see for visitors to this charming coastal city, now called Buffalo City in the Eastern Cape.

The Aquarium is open daily from 09:00 in the morning till 17:00 in the afternoon The Seals show and Penguin feeding run daily at 11:30 in the morning and 15:30 in the afternoon Entrance fee is R28 for adults, R17 for children (3 to 18 years) R11 per child in school group and R17 for pensioners.

 

The basics of feeding and breaching behaviour explained

Why do humpbacks breach?

Both male and female humpback whales of all ages breach but only the humpback males sing. Although we do not know why they do it, the frequency, style and function may differ with season and location.

Breaching costs a lot of energy and calves appear to do it the most. Could it be that since they don’t have to search for food but feed on the very rich milk (45–60 percent fat) for at least 10 months, the nursing youngsters can play more don’t need to worry about wasting energy. Breaching could thus be a form of play that helps them to develop skills to use in later life.

Among adults, breaching is far more common in social species, such as humpbacks, that gather at their breeding grounds. This suggests that it plays a role in communication. For example, North Pacific humpbacks breach most in their southern mating areas and less frequently in their northern feeding areas. Regardless of where the behaviour occurs, it is often associated with whales joining or separating from a particular group. Another function of breaching could be to dislodge barnacles or parasites that from on the skin.

The region between the dorsal fin and fluke (tail) houses a phenomenally powerful muscle. This means that the whale is capable of breaching from just below the surface, and doesn’t need to dive deep beforehand to get a ‘running start’. (Unlike sharks)

Humpback Whale rorqual Photo: Audun Rikarsen

How do humpbacks feed?

It is thought that humpbacks find prey use their tubercles - a prominent series of bumps on the head. Each bump has a sensory hair, and it is possible that the whale uses these ‘whiskers’ to judge prey density in the water during bouts of feeding. Humpback whales are filter feeders. The upper jaw contains up to 400 baleen plates, which strain out the water to leave the food – often krill or schooling fish. The throat opening is merely the size of a football, so only small prey can be consumed. Humpbacks have 14–35 grooves, known as ventral pleats, that extend back to the navel. These allow the throat to expand massively as sea water rushes in during feeding.

Humpback Whale lobtail Photo: Audun Rikarsen

What is lob-tailing?

It is the action performed when slapping the tail hard against the water, sometimes several times in succession and may be social or defensive behaviour. The action has been seen in response to boats approaching too closely.

Have you noticed this behaviour?

A humpback whale smashes its wing-like pectoral fins against the water’s surface, often together, while the whale is lying on its back. They are largely white on the underside and a third of the animal’s total body length.

Source: WDC

 

edible beer topsA brewery created by fishermen, surfers and lovers of the sea have come up with a genius solution to end plastic 6-pack rings ending up in the ocean.

Their solution? Edible rings. (For the fish, of course)

It is estimated that by 2050, there will be more plastic in the ocean than fish. (that's insane.) These brilliant thinkers decided they would help put an end to this by creating edible rings instead of plastic, the fish can therefore eat them instead of getting stuck in them.

This material is made entirely of barley and wheat remains from the brewing process, all of which is 100 percent biodegradable and safe for fish, turtles, birds and other marine life to eat, unlike the plastic ring-holders that are now killing them by the millions.

Article originally appeared in Niume

 

barnacles-and-lice-on-a-right-whale

Some species of barnacles and lice have figured out what a rewarding choice of "real estate" the living bodies of dolphins and whales can be. They live their lives attached to the bodies of dolphins, whales and other marine species, Some of these “hitchhikers” exclusively attach to certain parts of marine mammals, creating their own microhabitats right on their unsuspecting hosts. The barnacles are filtering organisms, trapping food particles in water as the bits of food flow by.

Barnacles from the species Xenobalanus globicipitis, hang from the underside of a dolphin fin Barnacles from the species Xenobalanus globicipitis, hang from the underside of a dolphin fin

Poetic bottom line: from Francisco Javier Aznar, senior author of the study, published in the journal PLOS ONE.

"Some years ago, a colleague wrote rather poetically that riding a dolphin would be the dream for a barnacle for two reasons,"

First, the movement of water the dolphin produces around it during swimming is rather predictable and, therefore, can advantageously be used by barnacles..

Second, no predator can chase a fast dolphin to feed on their barnacles!"

Some of the bowhead whales in the icy waters off of Alaska today are over 200 years old

Drwaing of a Bowhead Whale Drawing of a Bowhead Whale

In Alaska’s North Slope, the population of bowhead whales seems to be recovering. But that’s really not the coolest part of this Alaska story. That’s right, some of the bowhead whales in the icy waters today are over 200 years old. Alaska Dispatch writes:

"Bowheads seem to be recovering from the harvest of Yankee commercial whaling from 1848 to 1915, which wiped out all but 1,000 or so animals. Because the creatures can live longer than 200 years — a fact George discovered when he found an old stone harpoon point in a whale — some of the bowheads alive today may have themselves dodged the barbed steel points of the Yankee whalers"

Herman Melville wrote Moby Dick in 1851, after a brief stint on a whaling ship. Summary:

"Finally, driven to desperation at twenty-one, Melville committed to a whaling voyage of indefinite destination and scale on board a ship called the Acushnet. This journey took him around the continent of South America, across the Pacific Ocean, and to the South Seas, where he abandoned ship with a fellow sailor in the summer of 1842, eighteen months after setting out from New York. The two men found themselves in the Marquesas Islands, where they accidentally wandered into the company of a tribe of cannibals. Lamed with a bad leg, Melville became separated from his companion and spent a month alone in the company of the natives. This experience later formed the core of his first novel, Typee: A Peep at Polynesian Life, published in 1846. An indeterminate mixture of fact and fiction, Melville’s fanciful travel narrative remained the most popular and successful of his works during his lifetime."

Thirty four years ago, scientists counted 1,200 whales. Today there are about 14,000 of the mammals out there. Bowhead whales get their name from their heads, says NOAA

The bowhead whale has a massive bow-shaped skull that is over 16.5 feet (5 m) long and about 30-40% of their total body length. This large skull allows the bowhead whale to break through thick ice with its head. The bowhead whale also has a 17-19 inch (43-50 cm) thick blubber layer, thicker than any other whale’s blubber. None of the whales in Alaska, as far as we know, are white.

Bowhead whales see huge population rebound off Alaska's North Slope

Bowhead Whales are doing a remarkable recovery Bowhead Whales are doing a remarkable recovery

Bowhead whales counted from a sea-ice perch north of Barrow are “doing beautifully,” according to Craig George with the North Slope Borough. Since 1978, George has counted bowhead whales for an eight-week stretch each year from mid-April until June. The whales, which spend their lives in arctic waters, migrate past Point Barrow during that time. Since George and his colleagues began recording whale numbers 34 years ago, their counts have increased from 1,200 animals in 1978 to 3,400 in 2011. From those numbers of whales seen, George estimates there are now 14,000 to 15,000 animals.

“It’s pretty dramatic how it’s changed,” George said.

Bowheads seem to be recovering from the harvest of Yankee commercial whaling from 1848 to 1915, which wiped out all but 1,000 or so animals. Because the creatures can live longer than 200 years — a fact George discovered when he found an old stone harpoon point in a whale — some of the bowheads alive today may have themselves dodged the barbed steel points of the Yankee whalers.

That was just one nugget of northern news presented at the fall meeting of the American Geophysical Union, a five-day gathering of more than 20,000 scientists held in early December 2012 at the Moscone Center in San Francisco. A few more:

Descending permafrost

Permafrost researcher Nikolay Shiklomanov has for 18 years shoved pointy steel probes into the ground around Barrow to determine how much of the ground thaws by the end of each summer. When he hits something hard, he knows he has reached permafrost, ground that remains frozen all year. The depth his probe penetrates at the end of summer is called the “active layer.” It represents how much soil thaws each year; beneath it is permafrost.

Though he knew air temperatures were getting warmer in Barrow, the George Washington University scientist noticed the thickness of the active layer had not changed much in 18 years of probing. That led him to look at the readings of differential global positioning systems receivers that showed him the precise elevations of his plots since 2003. He saw dramatic sinking and extrapolated. His conclusion: The ground surface of today is one foot lower than it was in 1990.

“The active layer appeared to be stable, but the permafrost table was going down,” Shiklomanov said. He added that most of Barrow is probably a foot farther from the stars than it was 20 years ago due to thawing permafrost.

Scorched North Slope

When a wildfire on the North Slope burned an area larger than Cape Cod in 2007, researchers wondered if it was the sign of a new era in which northern tundra, fueled by warmer air temperatures, burned like the boreal forest down south.

This summer, Ben Jones and other scientists targeted certain areas of northern tundra and found two other immense burn scars on the North Slope. Jones, of the U.S. Geological Survey Alaska Science Center, went out to northwestern Alaska to check out what looked like old burned areas in satellite images.

He found charcoal in both areas, which had dense shrubbery. He mapped out the apparent boundaries of the Ketik River Fire in far northwest Alaska and found it was even larger than the Anaktuvik River Fire in 2007. Dating of the charcoal at the site indicates the Ketik River Fire burned sometime between 1810 and 1920. He also mapped a fire scar from a smaller-but-still-significant 123,000-acre fire that burned around the Meade River sometime between 1880 and 1920.

Ned Rozell is a science writer at the University of Alaska Fairbanks' Geophysical Institute.

 

The skeleton shapes are fossils, some of at least 40 dead whales washed ashore en masse between 6 and 9 million years ago on a beach that is now slightly inland from Northern Chille Coastline. The skeleton shapes are fossils, some of at least 40 dead whales washed ashore en masse between 6 and 9 million years ago on a beach that is now slightly inland from Nnorthern Chile's coastline.

No, it's not a sand sculpture competition. The skeleton shapes are fossils, some of at least 40 dead whales washed ashore en masse between 6 and 9 million years ago on a beach that is now slightly inland from northern Chile's coastline. They provide the earliest known example in the fossil record of mass strandings of marine mammals.

The area has the greatest density of extinct marine mammals in the world, says Nicholas Pyenson of the Smithsonian Institution's National Museum of Natural History in Washington DC, who led the research. Unfortunately, much of the site now sits under the northbound lane of the Pan-American Highway.

Discovered in 2010 during excavations for the road, which links Alaska and Argentina, the fossil haul includes over 40 large baleen whales, an extinct species of sperm whale and an extinct walrus-like whale. Also found at the Cerro Ballena site – Spanish for "whale hill" – were skeletons of billfishes, seals and aquatic sloths.

Whale graveyard- researchers doing fieldwork. Whale graveyard- researchers doing fieldwork.

Researchers recorded the skeletons in situ using 3D photography (pictured above) before moving them to Chilean museums.

Pyenson and his colleagues think that the whales died at sea after consuming food contaminated with toxins from algal blooms and their bodies floated onto what was then a beach. So-called "red tides", caused by algal blooms, are also to blame for some modern mass whale strandings, says Pyenson.

There were no large land scavengers in South America at the time, so the bodies lay unmolested until sand buried them. The skeletons were found on four separate levels, suggesting this story was repeated at least four times.

Much of the site is now paved over, but the researchers are confident that the area still conceals hundreds more fossils. The University of Chile in Santiago aims to open a research station near the Cerro Ballena site to work with what's left.[youtube]http://youtu.be/qRLZ29mLdSQ[/youtube]

Skeleton of a fossil whale Skeleton of a fossil whale

Repeated mass strandings of Miocene marine mammals from Atacama Region of Chile point to sudden death at sea

Marine mammal mass strandings have occurred for millions of years, but their origins defy singular explanations. Beyond human causes, mass strandings have been attributed to herding behaviour, large-scale oceanographic fronts and harmful algal blooms (HABs). Because algal toxins cause organ failure in marine mammals, HABs are the most common mass stranding agent with broad geographical and widespread taxonomic impact. Toxin-mediated mortalities in marine food webs have the potential to occur over geological timescales, but direct evidence for their antiquity has been lacking. Here, we describe an unusually dense accumulation of fossil marine vertebrates from Cerro Ballena, a Late Miocene locality in Atacama Region of Chile, preserving over 40 skeletons of rorqual whales, sperm whales, seals, aquatic sloths, walrus-whales and predatory bony fish.

Much of the site now sits under the northbound lane of the Pan-American Highway. Much of the site now sits under the northbound lane of the Pan-American Highway.

Marine mammal skeletons are distributed in four discrete horizons at the site, representing a recurring accumulation mechanism. Taphonomic analysis points to strong spatial focusing with a rapid death mechanism at sea, before being buried on a barrier-protected supratidal flat. In modern settings, HABs are the only known natural cause for such repeated, multispecies accumulations. This proposed agent suggests that upwelling zones elsewhere in the world should preserve fossil marine vertebrate accumulations in similar modes and densities.

Narwhals are sometimes referred to as the unicorns of the sea because of the long, pointed horns that extend from their heads. Narwhals are sometimes referred to as the unicorns of the sea because of the long, pointed horns that extend from their heads.

The nerve-filled appendage helps the animals’ sense temperature and perhaps find prey and mates

Narwhals are sometimes referred to as the unicorns of the sea because of the long, pointed horns that extend from their heads. Male narwhals' tusks can grow up to nine feet long,. Male narwhals' tusks can grow up to nine feet long. They are actually modified teeth that protrude out from the corner of their mouth, rather than forehead-centred horns.

Scientists do not know what purpose the narwhal's tusk serves, exactly. They've speculated that it might be used for skewering enemy animals or for breaking through the icy Arctic waters where the animals live. One team hypothesized that the tusk serves as a sort of sensory organ, Wired describes, and recently decided to investigate that idea.

To put their hunch to the test, the researchers devised a "tusk jacket," Drake writes—a sort of plastic hoodie that fit comfortably over the narwhals' tusks but excluded the outside environment. The team changed the concentration of salt in the water that filled the tusk jacket, which acts as a proxy for temperature (more ice equals colder water with more salt, while less ice means warmer water with less salt). Wired:

He found that narwhal heart rates rose in response to high salt concentrations, presumably because these concentrations normally suggest that the sea is freezing and entrapment is possible. The animals’ heart rates dropped when the tusks were washed with fresh water, suggesting they could detect this change.

The team only tested the tusks for a response to salt but think the whales might also use their tusks for seeking out prey or finding mates. Why, what would you do with an extra long, sensitive tooth?

 Great White Sharks breach to hunt -- with split-second timing they grab their prey in one swift snatch. Credit: © Morne Hardenberg
Great White Sharks breach to hunt -- with split-second timing they grab their prey in one swift snatch. Credit:
© Morne Hardenberg Sharks are much older than dinosaurs. Their ancestry dates back more than 400 million years, and they are one of evolution’s greatest success stories. These animals are uniquely adapted to their ocean environment with six highly refined senses of smell, hearing, touch, taste, sight, and even electromagnetism. As the top predators in the ocean, great white sharks (Carcharodon carcharias) face only one real threat to their survival: us. The assaults are many. By-catch: the accidental killing of sharks by fishermen's long lines and trawlers. Illegal poaching: selling shark fins for soup. Illegal hunting: sports fishing for shark jaws as trophies. Nets: placed along coastlines to keep sharks away from beaches. Pollution: toxins and heavy metals that build

Life & Natural History

Brains over Brawn

When great whites gather, they seem to show different behaviors, from open-mouthed gaping at one another to assertive body-slams. These sharks are top predators throughout the world's ocean, predominantly in temperate and subtropical waters. Great whites migrate long distances. Some make journeys from the Hawaiian Islands to California, and one shark that swam from from South Africa to Australia made the longest recorded migration of any fish. Great White Sharks are powerful swimmers capable of going 50 kph Great White Sharks are powerful swimmers capable of going 50 kph The torpedo shape of the great white is built for speed: up to 35 miles per hour (50 kilometers per hour). And then there are the teeth -- 300 total in up to seven rows. But more than brawn, the great white shark has a tremendous brain that coordinates all the highly-developed senses of this efficient hunter. Its prey, including seals and dolphins, are very clever animals, and the shark has to have enough brains to outsmart them. Despite their reputation as lone hunters, great whites will cooperate with one another, hunting in groups and sharing the spoils. And some researchers have been surprised by how fast they learn. up in the shark's body. In some areas great white populations have plummeted by over 70%. If not stopped, it could lead to the extinction of this ancient species.

Shark Senses

Many scientists now believe that Great whites became the ocean’s top hunters through the evolution of supremely-adapted senses and physiology. Sharks have six highly refined senses: smell, hearing, touch, taste, sight, and electromagnetism. These finely honed senses, along with a sleek, torpedo-shaped body, make most sharks highly skilled hunters. Sharks have six highly refined senses: smell, hearing, touch, taste, sight, and electromagnetism. These finely honed senses, along with a sleek, torpedo-shaped body, make most sharks highly skilled hunters. SMELL Great white sharks' most acute sense is smell. If there were just a single drop of blood floating in 10 billion drops of water, they could smell it! Their nostrils are on the underside of the snout and lead to an organ called the olfactory bulb. The great white’s olfactory bulb is reported to be the largest of any shark. HEARING Shark external ears are hard to see: they are just two small openings behind and above the eyes. The ears may be small, but they’re powerful. Inside, there are cells that can sense even the tiniest vibration in the surrounding water. Sharks also have an ‘ear stone’ that responds to gravity, giving the animal clues as to where it is in the water: head up, head down, right side up, or upside down. VISION A great white sharks has great vision. The retina of its eye is divided into two areas – one adapted for day vision, the other for low-light and night. To protect itself, the great white shark can roll its eye backward into the socket when threatened. ELECTRO-RECEPTION Sharks have a sense that humans can only be in awe of – they can sense an electrical field. A series of pores on the shark’s snout are filled with cells called the Ampullae of Lorenzini that can feel the power and direction of electrical currents. Scientists have discovered that sharks can use this sense to navigate through the open ocean by following an electrical ‘map’ of the magnetic fields that crisscross the Earth’s crust. TASTE Great white sharks are opportunistic eaters. Depending on the season, area and age, they will hunt seals and sea lions, fish, squid, and even other sharks. They have taste buds inside their mouths and throats that enable them to identify the food before swallowing. TOUCH Great white sharks have an elaborate sense of touch through what’s called the lateral line – a line that extends along the middle of the shark’s body from its tail to its head. This line, which is found in all fish, is made of cells that can perceive vibrations in the water. Sharks can detect both the direction and amount of movement made by prey, even from as far as 820 feet (250 meters) away.

Diversity

Sharks come in all shapes and sizes. Today there are more than 440 known species -- from the 6-inch long dwarf lantern shark (Etmopterus perryi) to the 60-foot long whale shark (Rhincodon typus). The smallest shark, a dwarf lantern shark, is rarely seen and little-known The smallest shark, a dwarf lantern shark, is rarely seen and little-known Unlike typical fish, sharks do not produce large amounts of small eggs. Instead, they invest their resources in fewer, larger eggs which are more likely to grow into adults. Some sharks lay eggs, while others give live birth. Great white sharks gestate their pups for a year before giving birth – that’s longer than humans. Between 2 to 12 babies are born at a time. Great whites can live up to 60 years, maybe more. Most sharks are slow to grow and take a long time to mature. That means that on the whole, sharks reproduce only a few young, making them all the more vulnerable to extinction.

Evolution

Fossil tooth whorl of ancient shark. Fossil tooth whorl of ancient shark.

Shark Ancestors

We may think that great whites are massive, but their ancestors would likely have made them appear midgets by comparison. An ancient shark called the Megalodon (Carcharodon megalodon), appeared on Earth more than 20 million years ago. Based on fossil teeth, scientists believe these sharks could have been as big as a school bus—big enough to probably feast on whales. For a long time, scientists thought the Megalodon was the direct ancestor of great white sharks. But new fossil evidence, announced in November 2012, suggest that it was more closely related to an ancestor of mako sharks—smaller but faster fish-eating sharks. Another shark ancestor swam the ocean 290 million years before today. Picture a shark with a teeth shaped in a ring like a saw. This fossil comes from the long-extinct Helicoprion, a buzzsaw with fins. But what did this animal actually look like? All scientists had to go on was a few fossil specimens and came up with a litany of possibilities, some more plausible than others. The face of Helicoprion was finally uncovered when a well-preserved fossil was brought in for a CT scan, and the result was published in 2013. Most of the toothy spiral is buried in the fish's lower jaw, with just a few teeth emerging. Using the new evidence, the reconstruction is the most accurate to date—and proves some earlier reconstructions wrong. The study also found that Helicoprion is not the ancestor of a great white shark but, rather, to the chimaeras, a group of deep sea shark relatives.

Shark Relatives

An X-ray image of a Monterey skatereveals a spine that extends like a tail out from the pelvic fin. The skeletons of skates, rays, chimaeras, and sharks are made of cartilage, rather than bone. An X-ray image of a Monterey skatereveals a spine that extends like a tail out from the pelvic fin. Just look at these x-rays. Not a single bone. Instead, these are animals with skeletons made from cartilage. These boneless fishesare in a class called Chondrichthyes that includes sharks, skates and rays. Sharks are also distantly related to the mysterious and rare chimaeras, which are found in deep ocean waters. Their enigmatic behavior has earned them names like spookfish or ratfish. The skeletons of skates, rays, chimaeras, and sharks are made of cartilage, rather than bone.

Science

White Shark endangered Credit: Marine Dynamics Infogram -Endangered species: White Sharks
Credit: Marine Dynamics

Research

Geneticist Mahmood Shivji samples confiscated shark fin DNA Geneticist Mahmood Shivji samples confiscated shark fin DNA

DNA Identification

DNA is a key tool in criminal cases. And that’s not just true of crimes against people. It’s true of crimes against sharks. It’s illegal to hunt great white sharks in South Africa, Australia, New Zealand, Malta, Namibia, Israel and the United States and DNA testing by scientists like Mahmood Shivji can prove when a fisherman has broken the law. Watch Dr. Shivji talk more about using DNA from shark fins to determine what species of shark are being killed, often for use in shark fin soup.  

Collections

Shark Teeth at the NMNH

An array of teeth from ragged tooth sharks. Credit: © Robert Purdy/Smithsonian National Museum of Natural History An array of teeth from ragged tooth sharks.
Credit: © Robert Purdy/Smithsonian National Museum of Natural History The Smithsonian's National Museum of Natural History has one of the largest collections of fossil shark teeth in the world – more than 90,000 different teeth. The oldest date back about 360 million years to the Devonian Period. Shark teeth come in a wide variety of shapes and sizes (pdf), all depending on their purpose. Flat teeth are adapted for crushing and grinding. Sharp and pointy teeth make it easier to grasp and hold slippery prey. Serrated teeth are ideal for ripping and tearing prey too large to swallow in one bite.  

Human Connections

Great white sharks have many more reasons to fear people than people have to fear them. Thousands of sharks are killed every year especially for shark fin soup.

Why We Should Save Sharks

Shark attack headlines in South Africa Credit: © Alison Kock, Save Our Seas Shark attack headlines in South Africa
Credit: © Alison Kock, Save Our Seas Fear of sharks seems to be encoded in our genes. Yet humans are rarely attacked by a shark, while millions of sharks are killed by humans. Some populations of shark species, such as the shortspine spurdog, may have dropped by 95 percent. The sharks’ population decline has a ripple effect – throwing entire marine ecosystems out of balance. Shark species often are especially vulnerable to overfishing because of specific life characteristics, such as not mating until later in life, and giving birth to small litters of live young. Sharks even have allies from a group of people who you would least expect - shark attack survivors are banding together in order to urge people to protect sharks. Why save sharks? The reasons are many. Sharks keep the ocean healthy because they keep different prey species from becoming overabundant. Sharks keep the ocean clean by scavenging on dead animals. Sharks keep other species more fit by weeding out sick and weaker individuals. And sharks are beautiful – like lions and gorillas – crowning achievements of evolution.

Cultural Connections

A fisherman holds a freshly cut dorsal fin from a scalloped hammerhead shark (Sphyrna lewini). A fisherman holds a freshly cut dorsal fin from a scalloped hammerhead shark (Sphyrna lewini).

Shark Fin Soup

Shark fin soup is considered a delicacy in many Asian countries, once reserved only for the wealthy or for very special occasions. But rising incomes in Asia are having a disastrous impact on sharks. To make the soup, the fins of the sharks are sliced off and the rest of the body is tossed back in the water, dead or alive: a method called shark finning. It's estimated that 100 million sharks are killed annually to supply fins for soup. Fins from great whites can fetch the highest prices because of their rarity and size. In Hong Kong, Taiwan and China, conservationists and chefs are leading campaigns to stop serving shark fin soup. Every year, humans kill an estimated 100 million sharks. Removing sharks in large numbers can have ripple effects that throw entire ecosystems out of balance

Threats and Solutions

Dead sharks caught in nets off South Africa Credit: © Thomas Peschak, Save Our Seas Dead sharks caught in nets off South Africa
Credit: © Thomas Peschak, Save Our Seas

Shark Nets

Dozens of shark nets have been installed off the east coast of South Africa and Australia. These nets are meant to protect swimmers from rare attacks. The nets entangle, suffocate and kill sharks as well as indiscriminately kill other animals -- like rays, turtles, dolphins and whales

 

The rocky coast of California’s Farallon Islands. Credit: © NOAA The rocky coast of California’s Farallon Islands. Credit: © NOAA

Shark Sanctuary

Great white sharks are a global species – and saving them will take a global effort. Some steps have already been taken. Countries like South Africa, Namibia, Australia, New Zealand, Israel, and Malta have fully protected great white sharks in their national waters. In California, NOAA is protecting the sharks that feed in the Gulf of Farallones National Marine Sanctuary off the coast of California. And the international organization CITES has implemented a ban on all international trade of products that come from great white sharks.

 

Toxic algal bloom off Washington, US. Left is the natural colour, right has been enhanced to reveal chlorophyll concentrations (Image: SeaWiFS Project, NASA/Goddard Space Flight Center/ORBIMAGE) Toxic algal bloom off Washington, US. Left is the natural colour, right has been enhanced to reveal chlorophyll concentrations (Image: SeaWiFS Project, NASA/Goddard Space Flight Center/ORBIMAGE)

Toxic algal blooms are bad enough on the ocean surface, but now it turns out that the toxin in them sinks to the ocean floor – where it persists for weeks.

Far from degrading soon after the bloom, as previously assumed, new research suggests that the neurotoxin that causes shellfish poisoning, domoic acid, sinks to the ocean floor and could poison marine mammals, birds and humans.

"The first signs of an algal bloom are often birds washing up on the shore or seals acting funny, aggressive and twitching, looking as if they were drunk," says Claudia Benitez-Nelson of the University of South Carolina.

"We used to think that once the bloom died, the danger was over, but now it turns out that domoic acid is a 'gift' that just keeps on giving."

Benitez-Nelson's team are the first to look for the chemical in algae particles sinking through the ocean, as well as in sediment samples on the ocean floor, up to 800 metres down. They found copious amounts of the neurotoxin, reaching concentrations eight times the US federal limit for the substance in shellfish.

Toxic shock

The team also compared the peak of domoic acid levels from the sediment with those of algae blooms at the surfaces. Their findings indicate that the toxin reaches the bottom of the ocean in only three days but stays there for much longer – at least several weeks.

The speedy trip to the bottom is probably driven by dead algae clumping together at the surface to form heavier aggregates, says the team, a process that also protects the toxin from degradation.

Domoic acid gets broken down easily in water and by sunlight, but once the clumped algae are buried in the sediment, the toxin may stay protected until a bottom-dwelling organism eats it.

"Domoic acid is a rich amino acid that will be tasty to worms and other critters, who may suffer no ill effects from it," says Benitez-Nelson.

Raphael Kudela at the University of Santa Cruz in California says that the new work is "the missing link to explain why domoic acid also shows up in bottom-dwelling organisms like crabs and flatfish. These contain lots of commercially important species, but they are not yet monitored for domoic acid."

The new data warrants studies to test if these species should be included in future monitoring efforts, according to Kudela. So far, only shellfish that live close to the water surface are monitored.

To Benitez-Nelson, the most important next step now is to work out in more detail how much longer the domoic acid sticks around and into how many more organisms it gets.

"It is clearly a lot more prevalent and spread out than we thought before and this problem affects many areas, not just California. On top of this, all signs seem to point to further increases in the future as people dump more and more algae feeding nutrients into the ocean."

 

This strange sea creature is the amazing Portuguese man-of-war (Caravela Portuguesa) –.

Despite its outward appearance, the Portuguese man o’ war is not a jellyfish Despite its outward appearance, the Portuguese man o’ war is not a jellyfish

A jellyfish-like marine cnidarian of the family Physaliidae. Its venomous tentacles can deliver a powerful sting.

The venomous tentacles can deliver a painful sting. The venomous tentacles can deliver a painful sting.

Despite its outward appearance, the Portuguese man o’ war is not a jellyfish but a siphonophore, which differs from jellyfish in that it is not actually a single multicellular organism but a colonial organism made up of many highly specialized minute individuals called zooids. These zooids are attached to one another and physiologically integrated to the extent that they are incapable of independent survival.

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