This can be frustrating. Now take that feeling and multiply it by about a million, and you will have a pretty good idea what it feels like as a scientist trying to identify individual dolphins. For scientists studying wild dolphin populations, being able to identify individual dolphins is a vital component of their research.
Studies gathering information about individual dolphins are used for research on population size estimations, migration patterns, social structure, group movements, life histories, and behavior. For example; researchers may be interested in learning how often individuals within a group interact with other individuals — patterns of association. Scientists may want to learn what kinds of behaviors are being produced by the adults, the juveniles, the males, the females and so on — all of this requires the scientist to know and recognize which individual dolphins they are observing.
The most popular technique is photographing the dorsal fin of the dolphin as it breaks the surface to breathe — this is often called photo-ID. Dorsal fins can function a lot like human fingerprints — the notches and nicks along the edge of the fin allow researchers to recognize and categorize individuals.
There is even some pretty fancy computer software that will help researchers search through scanned dorsal fin images to try and match photographs to the fins of previously identified dolphins. Some dolphin species will have natural markings or coloring patters that are visible when they surface, and these can be used for ID as well.
For those scientists able to actually enter the water to film or photograph wild dolphins under water, or for those using an underwater camera from their boat, it is possible to identify dolphins based on a variety of body features.
Sometimes deformities like missing fins or a prominent under-bite can be used to ID individuals. Wild dolphins accumulate a huge variety of scars and marks throughout their lifetime: everything from shark bites to cuts and scratches from contact with rocks, and even injuries resulting from fights with other dolphins.
If the dolphin is unlucky enough to have a nasty scar, or a chunk missing from its fluke, a scientist will have a relatively easy time re-identifying this individual based on underwater video or still photos. For the Indo-Pacific bottlenose dolphins that the Dolphin Communication Project studies around Mikura Island, scars from shark bites are all too common. For images of cookie cutter and other shark bite scars from the Mikura dolphins, check out The Dolphin Pod website for links.
Since rake marks are often shallow, they will only be visible for a few weeks to a few months, and are not a reliable way to identify individuals over longer periods of time i. Some species of dolphins, like spotted dolphins, develop spots as they age.
If researchers remain vigilant and keep clear records of the development of these spots over years, these distinctive spot patterns will allow them to reliably recognize individuals. The key to being able to identify individual dolphins is keeping good records — well organized photographic and video records are invaluable. Many scientists will keep a book with sketches of individual dolphins that can be easily updated as dolphins accumulate new scars.
To learn about some of the research groups working on identifying individual dolphins as part of their research, visit The Dolphin Pod website for links. There is even a link to an online test to see how skilled you are at identifying individual dolphin dorsal fins.
You were seen associating with an adult female and two juvenile males. How have you been, Todd? Did you know that a killer whale, otherwise known as an orca, is actually a dolphin?
Orcas are in fact the largest dolphin species in the world today. So, why are they called whales and not killer dolphins? Which, by the way, sounds downright terrifying? Well, that is a good question, and there is no easy answer. So instead of an easy answer, here is a complicated one: There are around 35 species of oceanic dolphin. All of these species can be correctly referred to as dolphins because they are in the scientific family known as delphinidae. Species in this family all have cone shaped teeth, a single blowhole on the top of the head, among other morphological traits that separate them from the other families.
What makes this a little confusing is that the common name for many of these dolphin species as the word whale in the name. The killer whale is a fine example. But there are more, including the melon-headed whale, the pygmy killer whale, the false killer whale, the long-finned pilot whale, and the short-finned pilot whale.
To complicate the issue even further, all of the species I just listed are sometimes called blackfish, although they are of course not actually fish, and not really whales, but simply dolphins. You think that us confusing? Try figuring out how the word porpoise fits in. In North America, many people refer to dolphins the species in the family delphinidae as porpoises. They may even call a bottlenose dolphin, the most famous dolphin of all, simply a porpoise.
This term came about from fisherman who call most dolphin species a porpoise to differentiate between them and the dolphin fish, otherwise known as mahi-mahi. Now the problem is that science recognizes the porpoise as a different kind of animal altogether.
There is a scientific family known as phocoenidae that contains 6 species of what are officially known in science as porpoises. So to be scientifically proper, a porpoise is an animal belonging to the phocoenidae family, and the term porpoise should only be used to describe one of those 6 species.
Unless of course you are a fisherman and you want to call a melon-headed whale a porpoise, which you might do, even though it is actually a blackfish or officially a dolphin.
But let us return to the first question: what us a whale? Well according to official scientific terminology, there is no such thing as a whale at all.
Science does not formally use the standalone word whale to refer to any of the animals found in the scientific order cetacea; that is the order containing all animals commonly referred to as whales, dolphins and porpoises. The term whale is usually used in the common name of the largest of the animals in the order cetacea, including the blue whale, the sperm whale and the beluga whale. That is because the word whale in English was in use for many centuries before scientists came on the scene and tried classify all of the cetaceans, and it was probably applied rather indiscriminately to most large animals seen swimming in the oceans.
Nowadays, a scientist might refer to animals like the blue whale the species with baleen instead of teeth and grooves on their throats as rorquals, or they might call the Sperm whale by the name Physeter. Because common names often vary from place to place and language to language, the only way to be sure of what animal you are talking about is to use its scientific name. In English, a Killer Whale therefore was probably originally referred to as a whale simply because it is large; it otherwise has very little in common with an animal like the Blue whale.
As we now know, science recognizes the Killer Whale as a dolphin because it is in the delphinidae family. But here is one more snag: there are 5 species of freshwater river dolphins that are NOT in the dolphin family, but in separate families altogether.
These river dolphins are nonetheless correctly referred to as dolphins. As you can see, it us not easy to tell a dolphin from a whale. When in doubt, you can always just shout 'hey, look - there's a cetacean! Wouldn't it be easier if we all just spoke Latin? You may be aware that dogs have a hearing range well above that of human beings - they are capable of hearing high frequencies that humans simply are not able to hear.
But, did you know that dolphins have a hearing range that far exceeds that of humans and even dogs? In fact, dolphins are able to hear, and to produce, some of the highest frequency sounds of all mammals. Let's put this into perspective. Humans have a hearing range of around 20 Hz to 20kHz. Here is an example of a 60 Hz sound [play sound] - that is, 60 sound wave cycles per second.
The human voice produces a range of frequencies when we speak, but the main frequencies are between Hz and 2 kHz. Here is an example of a 1 kHz tone [play sound] - a tone that is pretty easy for humans to hear. The top range of human hearing is up around 18 or 20 kHz - depending on your age and gender.
As humans get older, we begin to lose our ability to hear these higher frequencies. I will now play an example of a 15kHz tone [play sound]. Did you hear it?
If not, it might be an indication that you are getting on in years. Of course, it is possible that your speakers or headphones are not able to produce a tone that high, so for now, let's blame it on the speakers. So what about dogs? Well, dogs are able to hear frequencies more than twice as high as humans - up around an impressive 45 kHz.
But dolphins can do even better than that! For the species whose hearing has been researched the most, the bottlenose dolphin, we know that they can hear frequencies as high as kHz. Yes, that's right - kHz! If a jump from 1 kHz to 10 kHz sounds like this [play sounds], can you imagine how much higher kHz must be?
Dolphins use high frequency click sounds as part of their echolocation, producing and listening to sounds in these high frequency ranges. These clicks can sometimes be heard by the human ear because they contain frequencies below 20kHz, but the loudest frequencies produced in a click are up around kHz. These high frequencies help a dolphin to pick out fine detail when is uses its echolocation to investigate an object. There is one other mammal that can best the dolphin when it comes to producing and hearing high frequencies: the bat.
Bats can produce and hear frequencies as high as kHz! Now that is a frequency response that not even the most expense 5. Can dolphins kill or stun prey with loud sounds? It certainly seems that way if you believe following headlines: Dolphins' killer sonar confirmed from ABC Science Online February Killer clicks from New Scientist 1 January These are, of course, thrilling headlines and far more interesting than the contents of the research papers that they describe.
Why quote the following tedious academic prose: "The propagation of click echoes vis-a-vis the contours and composition of the ensonified object must also be considered when conceptualizing efficacious listening positions" When you can say Mysterious monsters are killing fish with murderous death beams as appeared in The Santa Cruz County Sentinel.
However, sometimes reality can indeed live up to the hype - 'stunning prey with a blast of sound' is something that happens every day in the ocean. The diminutive snapping shrimp is capable of producing a dB blast using its specially designed claw, rendering unconscious any unsuspecting prey that happen to be passing by.
But, can dolphins do something similar? The hypothesis that dolphins can use loud bangs or deafening click sounds to debilitate, stun or even kill their prey has been kicking around the scientific world since the s.
It is known as the 'acoustic prey debilitation' hypothesis, and was first introduced in a popular article by Ken Norris and Bertel Mohl that appeared in The American Naturalist in This hypothesis addressed the question of how sperm whales, with their flimsy looking jaws, were able to capture and eat the fearsome giant squid that kept turning up in their stomachs.
These squid typically had no teeth marks on them at all, which begs the question; how did these whales manage to catch and then swallow an entire giant squid seemingly without a struggle? One possible explanation was that they used loud sounds to debilitate the squid so they could slurp them up without a fight. This hypothesis became very popular with the media as we have seen , but actual real live scientific evidence to support it was strikingly absent for decades.
Nobody had ever actually seen a sperm whale or dolphin do anything like this! But, conclusive proof was still lacking. However, new evidence from a paper just published in August in the Journal of the Acoustical Society of America provides some rather convincing evidence that seems to blow the acoustic prey debilitation hypothesis also known as the prey stunning hypothesis out of the water - so to speak.
A research team led by Kelly Benoit-Bird performed a series of simple experiments: herring, cod and sea bass - some of the favorite food of dolphins - were placed in water tanks with video cameras recording their every movement.
Click sounds recorded from real dolphins; both orcas and bottlenose dolphins, were played back to the fish at varying intensity levels and repetition rates. The result: no matter what the researchers threw at them, the fish didn't seem in the least bit bothered by all the fuss.
Even with clicks being played back at the highest volume that dolphins are capable of producing, the fish didn't even flinch. It seems that dolphin sounds simply don't have the oomph to rightfully be called a 'killer licks.
Is this the final chapter in the 'killer sonar' book? Probably not. Although this latest paper seems to prove that dolphins can not stun or kill their prey with sound, you never know when someone will dig up new evidence to prove that they can. That's the beauty of science!
Although they reached a speed of only 8. This is in line with other work by Tom Lang, a former Navy researcher, that came to similar conclusions.
Top image courtesy Figen Ciftci. Register or Log In. The Magazine Shop. Login Register Stay Curious Subscribe. Planet Earth. Newsletter Sign up for our email newsletter for the latest science news. Sign Up. Already a subscriber? Want more? The bow wave helps dolphins go faster with less energy, so if they're travelling in the same direction, it's like hitching a lift.
They may well just do it for fun though. Source: Dolphinear. How fast do dolphins swim? Those beads are then illuminated with a sheet of laser light.
By filming how the illuminated beads move in reaction to an object moving through the water, experts can determine the forces generated. But you can't do this with a dolphin. Since it could injure the animal, "no one's going to let you put little glass beads into a tank with a dolphin," said Fish. And researchers certainly can't shine potentially harmful laser beams at the mammals. But a chance meeting with Timothy Wei at the University of Nebraska, who studies Olympic swimmers, gave Fish and colleagues their solution.
Read about five epic human swims. Wei had devised a bubble curtain to stand in place of the illuminated glass beads so that he could determine forces generated by human swimmers. So Fish and colleagues created a bubble curtain at the University of California, Santa Cruz UCSC , where they performed experiments with two captive bottlenose dolphins.
One of the dolphins seemed a little more skeptical of the bubble curtain than the other, but with some coaxing from trainers, the marine mammals soon got used to it.
The results showed that a dolphin's tail, or fluke, is more than capable of producing enough thrust to speed the mammal through the water. The flukes are also flexible, which is key to enabling the dolphin to maintain a highly efficient way of swimming over a broad range of speeds. It could be that the fluke becomes stiffer the faster the dolphin swims, increasing its swimming efficiency at high speeds.
Or maybe the dolphins can actively control fluke stiffness by changing the tension of tendons in their tail, he said. Fish isn't sure how they're doing it, but the marine biologist and colleagues are in the midst of trying to figure that out.
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