When we think of whales, dolphins and porpoises (collectively known as cetaceans), a few major celebrity species come up time and again. The majestic blue whale, the charming bottlenose dolphin and the formidable killer whale are known to nearly everybody, but there are dozens of other species we are still discovering and learning about.
Marine mammals are especially hard to study as their deep ocean habitat isn’t exactly comfortable for us humans. However one thing is clear from the information we have: many are at risk of extinction, and some have already tipped over the brink.
We really don’t want them to leave us with a “so long and thanks for all the fish” before getting better acquainted, so here are ten whales, dolphins and porpoises you’ve probably never heard of.
10 Pygmy and Dwarf sperm whales
Sperm whales are among the best known cetaceans, partly thanks to Herman Melville’s Moby Dick (inspired by a real albino sperm whale called Mocha Dick). These iconic beasts have two much smaller and far less famous relatives, the dwarf and pygmy sperm whales.
Sperm whales get their name from a special organ in their forehead called the spermaceti. The famous sperm whale has a huge one which fills much of its distinctive rectangular head, and the dwarf and pygmy sperm whales have one too – much tinier though. The organ’s true function is unclear, but it’s nothing to do with the reproductive kind of sperm. It might help with buoyancy, or perhaps helps focus their inbuilt sonar system called echolocation. Maybe both.
The dwarf and pygmy sperm whales are actually smaller than many dolphins, growing to about the same length as a person. They resemble sharks in some strange ways: they have pointed snouts, a white underbelly and even fake gills behind the eyes. Mimicking a fearsome predator may help it avoid trouble in the open water.
9 Pilot whales
Pilot whales are actually dolphins, albeit very large ones at 3.5 to 6 metres (12 to 20 ft) long. They are part of the “blackfish” group which also includes the killer whale, the largest dolphin of all.
Humans, pilot whales and killer whales share a surprising common feature – we go through the menopause, where females lose fertility well before old age. Not many other species have this. The underlying connection seems to be our societies and extended family groups. Genetically speaking, it’s better for older women and female pilot whales to spend time caring for their grandchildren than having more kids of their own. Over time, the females lost the ability to conceive beyond a certain age entirely.
Pilot whales are weirdly prone to mass strandings, which can result in the deaths of around a hundred large and apparently healthy individuals. Nobody is entirely sure why this happens, especially as the stranded group members are not always closely related. It’s also not clear whether humans are responsible, indirectly or not. Perhaps our noises and lights on land and sea disorient the dolphins? However mass strandings have known about since Ancient Greek times when our global impact was far smaller. The jury is still out.
8 Right whales
At 11-18 metres (36-60 ft) long, right whales are some of the largest beasts on the planet. They can be easily identified by the pale knobbly growths on their heads which stick out in clear contrast to their smooth dark skin.
Many people assume they’re barnacle growths, but that’s only partly true. They are actually natural hardenings of the skin called callosities, not unlike the hard calluses we get from wearing uncomfortable shoes for too long. The pale colour of right whales’ callosities is caused by the myriad other creatures which live on the outgrowths. Barnacles do feature but the population mainly consists of large white crustaceans called whale lice.
Why these callosities evolved is uncertain, as the whale lice and barnacles don’t seem to either help or hinder the whale much. One theory is that they serve as a sort of armor against killer whales, one of their few natural predators. They have proven very helpful to scientists who have used the genetics of the lice to understand more about the evolution of their massive host.
7 Baiji / Chinese River Dolphin
The list of species at risk of extinction from human activity grows longer and longer, but for the Chinese River Dolphin, it’s almost certainly too late. A 2006 survey of the Yangtze River in China, the sole home of the baiji dolphin, returned nothing. Since the death of a captive male called Qi-qi in 2002, there has only been one confirmed sighting and nothing in the last decade. It’s possible there are still a few alive in some forgotten stretch of the Yangtze, but the chance of the species making a healthy revival is now is so tiny that the species is classed as “functionally extinct”.
The dolphin still lives in our minds as a harsh reminder of what can happen when humans and animals share space. The Chinese people use the Yangtze for water, transport, food and hydroelectric power generation. The Chinese River Dolphin had nowhere else to live. The last fifty years has seen major developments along the Yangtze such as the Three Gorges Dam project. In that same timeframe, water pollution and habitat loss pushed the species from many thousands to the point of no return.
With the Chinese River Dolphin now sadly out of the running, the worrying title of “most endangered cetacean” has been handed to the vaquita. This little porpoise looks like it’s just tried on make-up for the first time and has gone a little extreme with it. It is easily identifiable by the thick black markings surrounding the eyes and mouth set against a pale gray body.
Finding one to identify isn’t easy though. The vaquita lives only at the Northern end of the Gulf of California, and there are thought to be fewer than two hundred of them alive. The species was only discovered in 1958 but it seems we’re at risk of losing them before we’ve even got properly acquainted.
We know a little about them, though. For a marine porpoise, the vaquita really doesn’t like deep water. It’s very rarely seen deeper than 30 metres (95 ft) below the surface and indeed is content swimming around in water so shallow that its back sticks out of the surface. This does make them vulnerable to getting trapped in nets, the main cause of their current decline.
5 Boto / Amazon river dolphin
A close relative of the Chinese river dolphin discussed earlier, the Amazon river dolphin is faring a little better… at least for now. The boto comes in a wide range of colours from gray to off-white and even to vivid pink (LINK 19). Its tiny eyes see very little, but their use is limited anyway as the dolphin hunts for fish at night in the murky Amazon waters.
To catch prey the boto uses echolocation, a natural sonar system using high-pitched clicks which bounce off objects and back to the dolphin. Most dolphins do this, and they have a special organ called the “melon” to help them out. The melon is what gives dolphins their bulbous forehead, and is used to help focus their calls like a lens for sound. The boto depends on echolocation to survive. It can change the shape of its melon at will, giving it exquisitely fine control over the direction, distance and type of sound emitted.
4 Bottlenose whale
The bottlenose dolphin may be the most iconic dolphin around, but there are also bottlenose whales. The two aren’t closely related but if you squint a bit they don’t look too different, even if the whale is three times bigger at 7-9 metres (23-29 ft) long. A more subtle difference is that bottlenose dolphins have dozens of teeth but the northern bottlenose whale only has a couple. These poke awkwardly out of the front of its bottom jaw. Females, and some males, have none at all.
Northern bottlenose whales are found in the waters around the UK, Scandinavia, and Eastern Canada. They are one of the deepest diving whales, regularly plunging to 800 metres (0.5 miles) below the surface. Occasionally they find themselves stranded. In 2006 one somehow made its way up the Thames River in London, prompting the first whale rescue attempt from this river. Despite best efforts by the aid workers, the dolphin sadly didn’t make it. Its remains are now in the National History Museum in London.
3 Risso’s Dolphin
Adult Risso’s dolphins have a positively battered appearance. They acquire various scratches and scrapes throughout their life, mainly through tussles with other members of their species and squid that fight back to avoid becoming dolphin prey. These show up clearly as white scars against their darker gray backs. Some older individuals look so pale they can even resemble the white beluga whale.
They have a steep forehead, practically no snout and their mouth curves up into what could be seen as a vacant smile. They are not particularly endangered as a species, but on the 16th September 2014 about 10 Risso’s dolphins were slaughtered in Taiji Bay off the coast of Southwest Japan. This act commenced the Japanese annual dolphin hunting season. Taiji Bay is was the notorious focus of the documentary “The Cove” which won an Oscar in 2010 for revealing how it is frequently used by hunters to corner and trap the dolphins before killing them for their meat.
2 Bowhead whale
Bowhead whales are named for the vast bow-shaped (the shooting kind!) skull which takes up about one third of the length of the body. The bowhead is also one of the chunkiest whales out there, probably the heaviest weight for its body length. Much of the weight is extra thick layers of blubber which helps keep them warm in the cold Arctic waters where they make their home.
Judging by the face alone, the bowhead whale could be the cetacean equivalent of Grumpy Cat. The large arched mouth opens up to reveal long baleen bristles hanging from its upper jaw. Rather than biting or chewing their food, whales with baleen simply hold their mouth open as they swim around and let the bristles trap krill and other small prey while letting the water filter through. Other whales such as the blue whale and the humpback whale have baleen, but the bowhead wins the prize for the longest bristles, which are often over 3 metres (10 feet) long.
1 Commerson’s dolphin
The striking black and white Commerson’s dolphin has the stocky appearance of a porpoise, but they are most definitely dolphins. Males and females can be distinguished with a quick look at their underbelly – males have an oval shaped black belly patch whereas females have a “V” or horseshoe shape. The overall patterning differs between individuals so they’re pretty easy to tell apart.
Commonson’s dolphins are some of the least fussy eaters of the dolphins, which tend to have quite specialised diets. They’ll happily eat octopus, sardine, squid, herring, shrimp, whiting and even large sea-worms. And they need a lot of food – up to 10% of their body weight every day to stay healthy. They use the energy they get from their food to power their fast and active swimming habits. Rather than gliding smoothly through the water, the Commerson’s dolphin will erratically dart about, spinning around and even swimming upside down.
Which was your favourite lesser-known whale, dolphin or porpoise? This post was inspired by and takes references throughout from a great cetacean guide called Dorling Kindersley Handbook: Whales, Dolphins and Porpoises by Mark Carwardine. Click for source images – mostly courtesy of Wikipedia and Whaleopedia.