Tag: dolphins

The Amazing Bodies Of Dolphins


Dolphins have a number of extraordinary features so that they can thrive in their watery world.

The most obvious thing that dolphins need is air. They glide through the water so effortlessly, surfacing every few minutes to take a breath. Dolphins can dive to 200 m (600 ft).

Marine mammals take more air with each breath than other mammals, and they exchange more of the air in their lungs with each breath.

Their red blood cells can hold more oxygen and they have a much higher tolerance for carbon dioxide than we do. During each breath they exchange 80% of the air in their lungs, while humans only exchange 17%.

Even so, given the size of their lungs, they should run out of oxygen and drown before they can get that deep! How do they do it?

When diving, they cut off blood circulation to their skin digestive system and extremities, leaving only the heart, brain and tail muscles working. However, even these measures give insufficient time to plummet to those depths.

Dolphins and other marine mammals don’t get the bends (nitrogen narcosis) when they plummet to the depths of the ocean.

In human lungs, air remains all throughout the lungs and gas exchange continues in the alvoli, allowing nitrogen to be forced into the blood.

The alvoli of doplhins collapse at 3 atm of pressure, forcing the air back into the bronchioles where gas exchange does not take place.

How do dolphins (and whales) sleep without drowning?

Marine mammals have two basic methods of sleeping: they either rest quietly in the water, or sleep while swimming slowly next to another animal.

Dolphins also enter a deeper form of sleep at night where they become like a log floating on the water. When a baby dolphin is born it does not have enough body fat to float easily.

The baby stays afloat by being towed in its mother’s slipstream or wake even when it is sleeping. This means that the mother cannot stop swimming for the first several weeks of her baby’s life!

To avoid drowning, it is crucial that cetaceans retain control of their blowhole and recognize when it is at the surface. When sleeping, dolphins shut down half of their brain and one eye.

The other half stays awake at a lower level of alertness. The semi-conscious side watches for predators, obstacles, and signals when to rise to the surface for a breath of air.

After 2 hours, things are reversed, the active side goes to sleep and the rested side looks after vital functions. Amazing!

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Pass it on: Popular Science

180 Million-Year-Old Crocodile Had Dolphin-Like Features, Tells Tale Of ‘Missing Link’

The discovery of an ancient type of crocodile that lived during the Jurassic Period, at the height of the age of dinosaurs, has shed new light on the species.

The 180 million-year-old fossil, named Magyarosuchus fitosi, shows that some ancient crocodiles evolved to have dolphin-like features.

The fossil was analyzed recently and found to have abnormal vertebra in its tail fin, effectively combining two different families of crocodiles – one that had limbs for walking on the surface and a bone-like protective armor on its back and one that had tail fins and flippers to aid with swimming in the ancient seas.

This fossil provides a unique insight into how crocodiles began evolving into dolphin and killer whale-like forms more than 180 million years ago,” Dr. Mark Young, of the University of Edinburgh’s School of GeoSciences, said in a statement.

The presence of both bony armour and a tail fin highlights the remarkable diversity of Jurassic-era crocodiles.

The new finding was made after the team of paleontologists analyzed the bones, which had been kept at a museum in Budapest. The fossil was originally discovered in Hungary in the Gerecse Mountains.

With an estimated body length of 4.67–4.83 m [15 feet – 16 feet] M. fitosi is the largest known non-metriorhynchid metriorhynchoid,” the study’s abstract reads.

The abstract continues: “The combination of retaining heavy dorsal and ventral armors and having a slight hypocercal tail is unique, further highlighting the mosaic manner of marine adaptations in Metriorhynchoidea.”

In addition, the newly-discovered species had large, pointed teeth, used to grasp prey, the statement added.

The study was published on May 10, in PeerJ, a peer-reviewed scientific journal.

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Pass it on: Popular Science

This Are The Top 10 Most Intelligent Animals On The Earth

In case you hadn’t heard, humans aren’t the only intelligent beings on planet Earth. In fact, we have plenty of company, and you may be surprised to learn who else is on the list.

1. Chimpanzees

Chimpanzees and humans are remarkably similar, sharing about 99 percent of our DNA. Chimps are our closest living relatives, and like humans, live in social communities and can adapt to different environments.

They can also learn sign language.

Chimpanzees can walk upright on two legs if they choose, and while they are primarily vegetarians they consume meat on occasion.

Chimps make and use tools, such as stones to open nuts and leaves to soak up drinking water. They reach reproductive age at around the same time humans do – 13 for females and 16 for males.

2. Bottlenose Dolphins

Bottlenose dolphins are one of just a handful of species in the animal kingdom that are able to use vocal learning to develop their own vocal signature.

Early in life, each dolphin creates its own unique vocal whistle that gives it an individual identity.

Because each whistle is unique, dolphins are able to call to each other by mimicking the whistle of a dolphin they want to communicate with. It’s the equivalent of calling each other by name.

Many dolphins establish strong social attachments and will stay with injured or ill members of the group, helping them to the surface of the water so they can breathe if necessary.

There are also reports of dolphins protecting human swimmers from sharks by swimming in circles around them, or rushing the sharks to shoo them away.

3. Elephants

Elephants’ brains are bigger than the brains of any other land animal, and the cortex has as many neurons as a human brain.

The ability of elephants to learn is impressive, and they are also self-aware – they can actually recognize themselves in mirrors!

In the wild, these highly social animals demonstrate helpfulness, compassion, and empathy. Their trunks and feet generate seismic activity that allows them to communicate with one another on a wide variety of subjects.

Elephants are likely the only large land-dwelling mammals that communicate using seismic signals.

4. African Grey Parrots

Known as the Einsteins of the parrot world, African Greys are highly intelligent. Studies have shown that the birds possess abstract, inferential reasoning abilities.

They appear to have some understanding of causality and use it to reason about the world.African Greys also show their smarts with their counting abilities and vocalization skills.

5. Rats

The ability to think about thinking is called metacognition, and a few years ago scientists discovered that rats, like humans, can make decisions based on what they do or do not know.

Studies also show that rats are surprisingly self-aware, they’re ticklish, and they dream just as we do. Pet rats are extremely social and form strong bonds with their owners.

They learn their names and come when they’re called, and they beg for time out of their cage to play and interact with their owners.

6. Crows

A crow’s brain is about the size of a human thumb, which is huge relative to its body size. This puts their intelligence on a level with primates, and gives them the ability to solve complex problems.

Scientists have discovered that crows recognize and remember individual human faces. Different areas of a crow’s brain light up when it sees a person it perceives as friendly or threatening.

7. Dogs


When it comes to canine companions, “smart” means different things to different people. Some people feel an obedient dog is smart, while others believe a dog with a mind of her own is more intelligent.

Very agreeable dogs are considered smart by most human standards.

Humans judge the intelligence of dogs based primarily on how quickly they learn to obey our commands, how well they perform, and whether they are able to learn human-type stuff like identifying objects.

8. Pigeons

Studies show that pigeons are able to learn abstract mathematical rules, and in fact are the only non-humans other than rhesus monkeys with the ability.

These much-maligned birds also have the ability to make extremely intelligent choices, and have highly evolved pigeon problem-solving skills.

Pigeons are also able to recognize individual people, most likely by their facial characteristics.

9. Pigs

According to some experts, pigs are among the smartest, cleanest domestic animals around – more so than cats and dogs.

Researchers who have studied pigs have learned they have excellent long-term memories, solve mazes easily, can comprehend a simple symbolic language.

They love to play and play-fight with each other, can learn to operate a joystick to move an on-screen cursor, and use a mirror to find hidden food.

10. Octopuses

Octopuses have the largest brains of any invertebrate. The common octopus has about 130 million neurons in its brain. A human has 100 billion.

However, three-fifths of an octopus’ neurons are not in the brain; they’re in its arms. Each arm has a mind of its own, so to speak, and if cut off, will wander away and even grab at food as it did while still attached.

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Pass it on: Popular Science

Killer Whales Should Not Be Kept In Captivity

The release of the documentary Blackfish in 2013 shined the national spotlight on the perils and problems of killer whale captivity.

Focusing primarily on killer whale aggression against trainers at SeaWorld and the associated fallout in the wake of veteran trainer Dawn Brancheau’s death in 2010, the film made a strong case against keeping killer whales in captivity.

Killer whales, also known as orcas, aren’t really whales at all. Though in the same infraorder, Cetacea, they are actually dolphins — the largest dolphins, in fact.

They generally weigh between 6,000 and 15,000 pounds when fully grown and stretch 30 feet long from fluke (tail) to rostrum (nose). In the wild, they are apex predators, hunted by no animal apart from man.

In captivity, however, the tides are turned on man. In the half-century that humans have kept orcas in tanks, there have been dozens of documented incidents of aggression, resulting in six deaths.

Orcas form complex societies reminiscent of those seen in chimpanzees. But in captivity, these hierarchies are severely muddled.

Often, a dominant female (orcas are matriarchal) asserts herself, usually violently. In the cramped conditions of captivity, other whales suffer lacerations from her intimidating tooth rakes.

Captive orcas also suffer from a wide range of health problems not seen among wild ones.


Their shallow pools render them vulnerable to higher-than-normal levels of ultraviolet radiation from the sun, which suppresses their immune systems.

They also spend more time exposed to the air than in the wild, often moving slowly due to the restrictive size of their habitats. Thus, orcas are prime feeding targets for mosquitos.

In fact, two captive orcas have died from mosquito-borne illnesses. Perhaps the most emblematic health problem associated with captivity is the collapse of the orca’s daunting, shark-like dorsal fin.

Though not actually harmful, the deformity affects over half of killer whales in captivity. Less than 10% of animals in the wild are afflicted.

Killer whales are extremely intelligent creatures, one of the few capable of passing the mirror self-recognition test. It’s no surprise, then, that they are easily subject to boredom in captivity.

One of the ways this manifests is paint nibbling. Whales often use their teeth to peel the paint off of their enclosure’s inner walls, similar to a human biting his fingernails, if his fingernails were made of concrete.

Almost all the whales in SeaWorld wear down their teeth, Hargrove says, dealing damage that requires regular dental procedures to prevent the growth of potentially deadly bacteria.

All of these issues contribute to a startling statistic. While most animals in captivity outlive their wild counterparts, orcas in captivity live shorter. Orca activists claim the gap is wide, while SeaWorld claims that there’s no gap at all.

The best estimates say that captive lifespan is slightly reduced, but improving. Male and female killer whales survive an average of 31 and 46 years in the wild, respectively.

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Pass it on: New Scientist