Marine mammals are difficult for scientists to study; they spend most or all of their lives in and around water habitats. Because of their vastness (hundreds of thousands of square kilometers) and depth (thousands of meters), marine mammal habitats are difficult for humans to access and explore. Cetaceans – whales, dolphin, and porpoises – spend their entire lives in the water and are thus even harder to study than other marine mammals like otters or seals, which periodically come back to land to rest, play, and reproduce. The hardest species to observe are the deep-diving whales like beaked whales because they spend so much more time underwater.
However, studying cetaceans has become easier in the past few years. Better boats, new technologies like drones, and improved tracking devices like satellite tags all contribute to easier, more accessible, and better studies of cetacean biology. With powerful computers and creative math, researchers are now able to quantify the amount of nutrients a whale can cycle in a single day. The amount is staggering, the same weight as about 7000 pizzas.
Deep-diving whales
One family of cetaceans, the beaked whales (Ziphiidae), is still proving incredibly hard to study. These toothed whales look a lot like robust dolphins with long pointy faces. But, they can dive and hold their breath for hours at a time! Beaked whales are boat-shy, live in deep offshore waters, and don’t stay at the surface very long. This makes them hard to study even with cutting-edge research methods. The few tracking tag records we have, though, indicate that some of these animals can dive to depths of nearly three kilometers while holding their breath for three hours or more. That’s enough time to watch La La Land (2016) and still start Free Willy (1993), over a distance equal to 249 London city buses lined up nose to rear. Talk about transport in style!
As you can imagine, this makes beaked whales quite difficult to see, and nearly impossible to watch routinely. Because of this, we understand very little about the role they play in their environment, and we’re still finding new species. For example, the newest beaked whale species, Ramari’s beaked whale, was described in 2021, with another likely to be described soon!
Finding a needle in a haystack
This difficulty is counterintuitive to how we often imagine large animal studies should go. Because of their size, we think they should be easier to find and observe. But, since oceans make up 70% of the planet’s surface and we humans need some sort of flotation to be on the water for any great length of time, whales can easily elude us. In addition to their deep-diving behavior and short surface intervals, the offshore habitats beaked whales inhabit are vast and less frequented by boat traffic than coastal regions. Finding a grayish-colored beaked whale amongst grayish-colored waves in the open ocean is like finding a needle in a haystack – maybe even harder!
Stranded whales tell us secrets
Unfortunately, sometimes cetaceans end up on beaches, where they certainly don’t belong. When living cetaceans strand, specially trained teams jump into action to try to help the animal. These teams, often largely comprised of volunteers, work to keep the animal comfortable, determine why it stranded, and return it to the water. Sometimes cetaceans die before they can be returned to the water, or strand already dead. When this happens, the carcasses become available for scientific collection and study.
Collecting and studying stranded cetaceans has been going on for a long time. Some of the only information on beaked whales came from carcasses that were collected in the 1700s or 1800s. These stranded and archived cetaceans, termed “specimens of opportunity”, provide an incredible opportunity to study these elusive animals. Museums have been a safe repository for stranded specimens for hundreds of years. Thus, they hold centuries’ worth of information about these species and their habitats. The challenge for scientists becomes how to unlock the secrets stored in these specimens.
The chemistry behind beaked whale research
Like a lot of biology students, I never thought I would use chemistry or physics to study marine mammals. What a fool I was! Chemistry, physics, and creative math provide the perfect avenues to use specimens of opportunity to study beaked whales. Using a chemistry technique called stable isotope analysis, we can learn where these animals live, what they eat, and how that may change across their lives.
Isotopes are forms of elements whose atoms differ in the number of neutrons in their nucleus. Stable isotopes occur naturally, but unlike their radioactive counterparts which are highly unstable (read: big boom), stable isotopes stay around for basically eternity. In food webs, stable isotopes are absorbed from the environment by plants. When the plants are eaten by animals, the plant’s ratio of stable isotopes is preserved and passed to the animal. This continues as animals get eaten by other animals, all the way up the food chain. As animals absorb those isotopes, they are incorporated into the animal’s tissues. Due to complex biochemical processes used to make tissues, the isotope ratios change in predictable patterns at each step of the food chain. We use these patterns to measure animal diets, meaning that (according to stable isotopes, at least) you are what you eat!
You are what you eat
Scientists use these patterns to our advantage! The two primary stable isotopes we use in wildlife studies are carbon and nitrogen. By analyzing the carbon in an animal’s tissues, we can trace back to the plants at the base of the food web, revealing the environment or location where the animal’s food originated. Nitrogen can give us an idea of how high our species is in the food chain. Nitrogen isotopes “stick” in animals more readily than carbon because normal losses of mass (tissue repair, reproduction, etc.) retain the isotopes. This cycle continues up the food chain: predators eat more heavy nitrogen while they lose the remaining light nitrogen.
We start by collecting a tiny sample from the stranded whale. Different tissues tell us different things, so we think through what questions we want to answer before sampling. For example, teeth and baleen give us information over a long period of an animal’s life, but skin and blood tell us about its recent history. We powder our sample and weigh a tiny amount (fractions of a milligram!) into a tin cup. We push our cupped sample through a large machine called an Isotope Ratio Mass Spectrometer (IRMS). An IRMS uses powerful magnets to measure ratios of heavy to regular isotopes. By analyzing these ratios, we can determine how diverse the whale’s diet was, how high it existed in the food chain, and other details about its life.
Zaaz preparing and weighing the samples for stable isotope analyses. The analyses require a lot of precision and patience — Credit: Z. Santhanam
Wildlife studies use other isotopes, including oxygen, sulfur, and hydrogen, but not as extensively as carbon and nitrogen. Scientists around the globe are developing applications for these isotopes that will help us understand the animals with whom we share the world, pushing the field of isotope science to new heights all the time!
Studying past, present, and future beaked whale populations
Using stable isotope techniques to analyze samples from stranded animals allows us to reconstruct their lives, giving us valuable insights into their behaviors, diets, and habitats—all without needing to directly observe them in the wild. This approach helps us understand these species in ways that would otherwise be impossible.
This is immensely useful for whale scientists, and even more so for beaked whale scientists. Because we know so little about beaked whales, every stranded individual provides us with more information about their ecology! Collaborating with institutions like natural history museums allows us to study the whale specimens they preserve. These studies help us examine generational changes in beaked whale populations to measure the impact our ever-changing oceans have on them. Though current knowledge of beaked whales is still murky, chemistry-based techniques like stable isotope analysis ensure that the future of whale science is very bright indeed!
Sources and further reading
- Hobson, Keith A., John P. Whiteman, and Seth D. Newsome. “New frontiers in the application of stable isotopes to ecological and ecophysiological research.” Frontiers in Ecology and Evolution 11 (2023): 1259402.
- Newsome, Seth D., et al. “A niche for isotopic ecology.” Frontiers in Ecology and the Environment 5.8 (2007): 429-436.
- Shearer, Jeanne M., et al. “Diving behaviour of Cuvier’s beaked whales (Ziphius cavirostris) off Cape Hatteras, North Carolina.” Royal Society Open Science 6.2 (2019): 181728.
Di you enjoy this post? Make sure to check out others on beaked whales:
Zaahir Santhanam, or Zaaz, is a PhD Student at the University of North Carolina Wilmington studying beaked whale ecology! His current research centers around using new techniques to further understand the lives of these elusive whales. He loves surfing and burritos almost as much as science!
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