The world’s largest animals have been hiding something. The bodies of the giant rorqual whales—including the blue, fin and humpback—have been regularly displayed in museums, filmed by documentary makers, and harpooned by hunters. Despite this attention, no one noticed the volleyball-sized sense organ at the tips of their lower jaws. Nicholas Pyenson from the Smithsonian Institution is the first, and he thinks that the whales use this structure to coordinate the planet’s biggest mouthfuls.
Archive for the ‘Dolphins and whales’ Category
New sense organ helps giant whales to coordinate the world’s biggest mouthfuls
Dolphins that help humans to catch fish form tighter social networks
In the coastal waters of Laguna, Brazil, a shoal of mullet is in serious trouble. Two of the most intelligent species on the planet – humans and bottlenose dolphins – are conspiring to kill them. The dolphins drive the mullet towards the fishermen, who stand waist-deep in water holding nets. The humans cannot see the fish through the turbid water. They must wait for their accomplices.
As the fish approach, the dolphins signal to the humans by rolling at the surface, or slapping the water with their heads or tails. The nets are cast, and the mullet are snared. Some manage to escape, but in breaking formation, they are easy prey for the dolphins.
According to town records, this alliance began in 1847, and involves at least three generations of both humans and dolphins. Today, there are around 55 dolphins in the neighbourhood, and around 45 per cent of them interact with the fishermen.
Now, Fabio Daura-Jorge from the Federal University of Santa Catarina, Brazil studied Laguna’s dolphins to learn how their unusual collaboration has shaped their social networks. He spent two years taking photographs of the local dolphins, and noting where they travelled and who they were associated with. As is typical for bottlenose dolphins, the Laguna individuals formed a ‘fission-fusion’ society – they all belonged to the same large group, but they had specific ‘friends’ whom they would spend more time with.
The dolphins roughly split into two separate groups, based on their tendency to hunt with humans. Those that co-operated with the fishermen were more likely to spend time with each other than the uncooperative individuals. Likewise, the uncooperative dolphins showed a tendency to stick to their own clique.
One individual even seemed to act as a “social broker”, and spent time with individuals from both groups.
Of the two groups, the human-helpers seemed to form stronger social ties. It is not clear if helping humans means they spend more time together, or vice versa. But certainly, their close associations increase the odds that one dolphin will learn the hunting technique from its peers.
This fits with what we know about bottlenose dolphins. They are extremely intelligent animals and different populations have developed their own quirky foraging traditions by learning from one another. Some use sponges to guard their snouts when they root about the ocean floor for food. Others can prepare a cuttlefish meal by sequentially killing and stripping them.
Daura-Jorge now wants to understand why only some of the dolphins help the fishermen, given that doing so clearly provides them with benefits, and all of them have the opportunity to help. By analysing the dolphins’ genes, he hopes to piece together their family trees, and work out if mothers pass on the behaviour to their calves.
Reference: Daura-Jorge, Cantor, Ingram, Lusseau & Simoes-Lopes. 2012. The structure of a bottlenose dolphin society is coupled to a unique foraging cooperation with artisanal fishermen. Biology Letters http://dx.doi.org/10.1098/rsbl.2012.0174
Bonus: There are several cases around the world where dolphins feed on the discarded remains of fish thrown away by humans. But the Laguna animals do far more than that – the fisherman wouldn’t catch any fish at all without their help. A similar alliance takes place half a world away in Burma, where Irrawaddy dolphins also fish cooperatively with humans.
More on dolphin behaviour:
- Will we ever… talk to dolphins?
- When meeting up at sea, bottlenose dolphins exchange name-like whistles
- Dolphin detects electric fields with ex-whisker pits
- Dolphins stay alert after five straight days of round-the-clock vigilance
- How dolphins prepare the perfect cuttlefish meal
- Sponging dolphins keep it in the family
- Boto dolphins woo females with chat-up vines
Will we ever… talk to dolphins?
Here’s the fourth piece from my new BBC column
“What’s that Flipper? The treasure is over there?” So went a typical plotline for the popular TV series featuring the cute, bottlenosed dolphin who could communicate with his human guardians, and who – in the time-honoured fashion – used his animal powers to apprehend criminals.
The idea that animals like Flipper can communicate with humans is not just the preserve of the small and big screen. History is littered with celebrity animals who have communicated with human scientists, with varying degrees of success. Many apes, including Washoe and Nim the chimps, and Kanzi the bonobo, have learned to communicate by using sign language or symbols on a keyboard. Alex, an African grey parrot learned over 100 English words, which he could use and combine appropriately; his poignant last words to Irene Pepperberg, his scientist handler, were “You be good. I love you. See you tomorrow.”
Dolphins hold a particular fascination; we are captivated by their intelligence and beauty, and swimming with dolphins features regularly on lists of things to do before you die. Denise Herzing has a lifetime of such experiences. For the last 27 years, she has been swimming with a group of Atlantic spotted dolphins in Florida as part of the Wild Dolphin Project. She can identify every individual and they, in turn, seem to trust and recognise her. It is a solid foundation for the boldest attempt yet to talk with dolphins.
One-way chat
“Talk” is tricky to define. A SeaWorld trainer who prompts a dolphin to jump for fish is arguably communicating with it. But such simple one-way interactions are a far cry from the conversational world of Dr Doolittle. Here, the dolphin responds, but says nothing intelligible back. Herzing’s vision is much more ambitious – she wants to establish two-way communication with her dolphins, with both species exchanging and understanding information.
The idea of talking to dolphins has a long and chequered history. It was widely publicised in the 1960s by John Lilly, who argued that dolphins have such large brains that they must be extremely intelligent and have a natural language. All we had to do was to “crack the code”. Much of Lilly’s work was highly questionable. He once flooded a house to keep a captive dolphin, instigated failed attempts to teach them spoken English, and even gave the animals LSD (while taking the drug himself). But there is no denying his influence in popularising the idea of two-way dolphin communication. “He said that in a few years, we will have established complex dialogue with them,” says Justin Gregg from the Dolphin Communication Project. “And he was saying that every few years.”
Lilly was right about dolphin intelligence, but not dolphin language. A true language involves small elements that combine into larger chains, to convey complex, and sometimes abstract, information. And there is no good evidence that dolphins have that, despite their rich repertoire of whistles and clicks.
Little less conversation
Wild dolphin communication is hard to study. They are fast-moving and hard to follow. They travel in groups, making it hard to assign any call to a specific individual. And they communicate at frequencies beyond what humans can hear. Despite these challenges, there is some evidence that dolphins use sounds to represent concepts. Each individual has its own “signature whistle” which might act like a name. Developed in the first year of life, dolphins use these whistles as badges of identity, and may modulate them to reflect motivation and mood. This year, a study showed that when wild dolphins meet, one member of each group exchanges signature whistles.
But beyond this, dolphin chat is still largely mysterious. “To communicate with dolphins, we need to understand how they communicate with each other in the natural world,” says psychologist Stan Kuczaj at the University of Southern Mississippi. “We still don’t know basic things like what the units of dolphin communication are. Is a whistle the equivalent of a “word” or a “short sentence”? We don’t know.”
We may not be able to understand them yet, but we know that dolphins can learn to understand us. In the 1970s, Louis Herman taught an invented sign language, complete with basic syntax, to a bottlenose dolphin called Akeakamai. For example, if he made the gestures for “person surfboard fetch”, Akeakamai would bring the board to him, while “surfboard person fetch” would prompt her to carry the person to the board. His experiments showed that dolphins could understand hundreds of words, and how those words could be combined using grammatical rules.
What’s my motivation?
Herman’s work was groundbreaking, but this was still one-way communication. It focused on comprehension, not conversation. In the 1980s, Diana Reiss had more luck by showing that dolphins could use underwater keyboards to make basic requests. When they prodded keys with their snouts, a whistle would play and Reiss gave a reward like a ball. Eventually, the dolphins used the artificial whistles to ask for the associated rewards.
But as conversations go, these were shallow ones. “The dolphins were only really interested in communicating about needs that they had, like a tool they needed or a fish they wanted,” says Kuczaj, who was involved in a similar project at DisneyWorld’s EPCOT Center. “We hoped they would also comment on other things going on in the aquarium but they didn’t.”
It is difficult persuading dolphins to learn some arbitrary signals, like a whistle signifying a ball, and then use them in a social context, admits Gregg. “They don’t seem to run with it the same way that chimps or bonobos have. The big stumbling block is motivation. Dolphins don’t seem to care.”
Herzing disagrees. She notes that captive animals, which often lack stimulation, will respond to systems like the underwater keyboards. She thinks that these experiments disappointed because they were cumbersome. “The dolphins swim very fast and went to where they were requested, but humans are very slow in the water. There wasn’t enough real-time interaction.”
Chat line
Herzing is trying to solve that problem with Cetacean Hearing and Telemetry (CHAT) – a lighter, portable version of the underwater keyboards. It consists of a small phone-sized computer, strapped to a diver’s chest and connected to two underwater recorders, or hydrophones. The computer will detect and differentiate dolphin sounds, including the ultrasonic ones we cannot hear, and use flashing lights to tell the diver which animal made the call.
The CHAT device can also play artificial calls, allowing Herzing to coin dolphin-esque “words” for things that are relevant to them, like “seaweed” or “wave-surfing”. She hopes the dolphins will mimic the artificial whistles, and use them voluntarily. By working with wild animals, and focusing on objects in their natural environment, rather than balls or hoops, Herzing hopes to pique their interest.
Herzing emphasises that her device is not a translator. It will not act as a dolphin-human Rosetta stone. Instead, she wants both species create a joint form of communication that they are both invested in. She hopes that CHAT will tap into the “natural propensity” that dolphins have “for creating common information when they have to interact”. For example, in Costa Rica, distantly related bottlenose and Guyana dolphins will adopt a shared collection of sounds when they come together, using sounds that they don’t use when apart.
As with past projects, all of this depends on whether the dolphins play along. Kuczaj says, “It’s a remarkable challenge because she is working with wild dolphins so they’ve got the option to participate or not.” Here, Herzing has an edge, since the animals know her, and vice versa. “We’ve been observing them underwater every summer since 1985,” she says. “I know the individuals personally – their personalities and relationships. We’ve got a pretty good handle on what they’d be interested in.” Perhaps this combination of cutting-edge technology and old-school fieldwork will finally produce the conversations that have eluded scientists for so long.
Giant squid, what big eyes you have. All the better to spot sperm whales with, my dear.
The giant squid sees the world with eyes the size of soccer balls. They’re at least 25 centimetres (10 inches) across, making them the largest eyes on the planet.
For comparison, the largest fish eye is the 9-centimetre orb of the swordfish. It would fit inside the giant squid’s pupil! Even the blue whale – the largest animal that has ever existed – has measly 11-centimetre-wide eyes.
So why the huge leap in size? Why does the giant squid have a champion eye that’s at least twice the size of the runner-up?
Dan-Eric Nilsson and Eric Warrant from Lund University, Sweden, think that the squid must have evolved its eye to cope with some unique challenge that other animals don’t face. They suggest that the world’s biggest eyes evolved to spot one of the world’s biggest predators – the sperm whale.
When meeting up at sea, bottlenose dolphins exchange name-like whistles
When we meet a group of strangers, one of the first things we’ll do is to introduce ourselves by name. Nicola Quick and Vincent Janik from the University of St Andrews have found that groups of bottlenose dolphins do something similar. When they meet one another in the wild, they exchange “signature whistles”. These whistles are unique to each individual, and they’re strikingly similar to human names. And it seems that they’re a standard part of a dolphin’s meet-and-greet etiquette.
The blue whale – how I met the largest animal that has ever existed
“I can see its tail,” says David Attenborough, perched on a small boat. “It’s coming up… it’s coming up! There! The blue whale!” Ever since I first saw The Life of Mammals, I’ve always remembered Attenborough’s joy at seeing the “largest animal that exists or has ever existed”.
I now know how he felt.
On Monday, off the southern coast of Sri Lanka, my wife and I had the privilege of seeing five blue whales.
Stone-cutter finds fossil whale in marble slabs
In July 2002, an Italian man named Mr Francioni found something strange. Francioni owns a marble-cutting company in the Tuscan town of Pietrasanta, and he had just acquired a block of Egyptian marbleized limestone. After slicing the block into six slabs, he discovered the fossilised bones of an animal within. Fossils weaken the strength of cut stone and many people discard them outright. But Francioni was excited: he thought he had found a dinosaur, and contacted the nearby University of Pisa.
He got through to Giovanni Bianucci. “As soon as I saw the slabs, I realized that the finding was even more important than a dinosaur, at least for me. I study marine mammals,” he says. Bianucci realised that the bones belonged to an archaeocete, one of the predecessors of modern whales and dolphins. The story might have ended there: Francioni already had an offer from a foreign private collector, who wanted to slabs for his living room. Thankfully, Pisa’s local government intervened. They bought the fossils for the University’s Natural History Museum, where they are now on permanent display.
Whales sucked before they sieved
The blue whale – the largest living animal on the planet – can eat half a million calories in a single titanic gulp. It accelerates to high speeds and lunges into a swarm of tiny krill. It opens the world’s biggest mouth, which expands like a balloon to swallow up to 110 tonnes of water. The mouth closes, and the tongue pushes the water against bristly plates called baleen, which filter out the krill.
The blue whale’s skull is specially adapted to allow it to engulf large volumes of water. If you push against your chin, nothing happens because the two halves of your lower jaw are firmly fused together at the front. That’s not the case for the blue whale. The joint between its lower jaws – the mandibular symphysis – is particularly loose and elastic, allowing the jaw to flex and expand with the incoming tide of water and krill.
This elastic joint is a defining trait of all whales that sieve their food from the water, including the blue, humpback and right whales. Not all of them are lunge-feeders. The right and bowhead whales swim through schools of plankton with jaws open, while gray whales suck up mud from the seafloor. But all of them rely on the elastic joint that allows them to open their mouths as wide as possible. It was an important innovation that allowed this group – the mysticetes, or baleen whales – to hunt the smallest of prey in the largest of volumes. It allowed them to evolve into the largest animals this planet has ever seen.
But that wasn’t always the case. Ancient whales had the same fused jaws found in toothed whales like sperm whale and dolphins (and, for that matter, humans). Now, Erich Fitzgerald from Museum Victoria in Melbourne has found a fossil that bridges the gap between this standard set-up and the flexible jaws of titans.
Dolphin detects electric fields with ex-whisker pits
If you look carefully at the snout of a dolphin, you’ll see two rows of tiny pits, known as vibrissal crypts, When dolphins are born, these pits house whiskers that soon waste away to leave empty craters. It’s tempting to think that the crypts as useless evolutionary throwbacks to a time when the ancestors of dolphins used whiskers to feel their way about. But these structures are far from useless. In at least one species of dolphin, they can sense electricity.
Nicole Czech-Damal from the University of Hamburg discovered this amazing ability by studying the Guiana dolphin, also known as the costero. It looks a lot like the familiar bottlenose dolphin, but its vibrissal crypts are far larger. Back in 2000, these prominent pits intrigued Guido Denhardt, who decided to look at them using a heat-sensitive camera. He found that the dolphin’s crypts produce spots of intense heat, burning as brightly on the camera as the whiskers of harbour seals.
The heat spots implied that, contrary to what people had thought, the vibrissal crypts are fuelled by a strong supply of blood. They are not useless vestigial organs – these crypts do something.
Blue whales can eat half a million calories in a single mouthful
The blue whale is the largest animal that has ever lived. Ironically, it sustains its massive bulk by eating some of the smallest creatures in the ocean – krill. A foraging whale lunges into a swarm of these shrimp-like animals, accelerating to high speed with its mouth open at a right angle. Pushed back by the rush of water, its mouth expands and its tongue (itself the size of an elephant) inverts to create more room. The whale engulfs up to 110 tonnes of water and any krill within is filtered out and swallowed.
There’s every reason to think that filtering out small prey is an incredibly efficient way of feeding. The largest fish, both living (the whale shark and basking shark) and extinct (Leedsichthys), are all filter-feeders. And the biggest of the whales – the blue and fin – both use this technique. But no one has ever put the reputed efficiency of filter-feeding to the test, by calculating how much energy a blue whale spends on its lunges and how much it gets in return. Jeremy Goldbogen at the University of British Columbia is the first.
