Jun 12
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ARKive’s Top Ten Whales and Dolphins

Last weekend marked World Oceans Day, a day dedicated to celebrating the beauty and bounty that our oceans provide, and raising awareness of the importance of protecting them. Here at ARKive, we’ve been inspired by the watery realm, and thought we’d honour our fellow mammals by submerging ourselves in the wonderful world of whales and dolphins.

Winged whale

Humpback whale image

An instantly recognisable species, the humpback whale is named for the distinctive ‘hump’ formed by its back as it prepares to dive. Its long flippers, another characteristic feature, can grow up to five metres in length, and contribute to this vocal cetacean’s scientific name, Megaptera novaeangliae, which means ‘big-winged New Englander’.

Marine misnomer

Orca image

Orcas are easily distinguishable by their striking black and white markings and their imposing, triangular dorsal fin. Interestingly, these fascinating marine mammals have a rather misleading alternative name – killer whales. While they are certainly efficient predators, they are not whales and are, in fact, the largest members of the dolphin family. Orcas usually hunt in pods, although individuals from some populations are known to deliberately beach themselves in order to snatch sea lions resting on the beach before wriggling back to sea with their prey.

Social cetacean

Dusky dolphin image

The charismatic dusky dolphin is a highly social species, sometimes being found in pods of over 1,000 individuals and frequently associating with other cetacean species. This beautiful marine mammal is said to be one of the most acrobatic of all dolphins, often making energetic leaps out of the water and performing impressive tumbles in the air.

Underwater unicorn

Narwhal image

There’s no mistaking the unique narwhal, a species famed for the hugely elongated tooth or ‘tusk’ which protrudes from its upper lip. The longest of these incredible appendages was recorded at over 2.5 metres in length, and the males use these bodily weapons in jousting bouts. The narwhal is found throughout the waters of the Arctic, as well as in the northern Atlantic Ocean, and it tends to stay close to pack ice.

Cerebral cetaceans

Bottlenose dolphin image

Quite possibly the most famous of all cetaceans, the bottlenose dolphin is much-loved by many. This extremely intelligent species is highly social, and uses a wide range of clicks and whistles to communicate with other members of its pod. Like some other species of cetacean, the bottlenose dolphin seeks out prey using echolocation, and individuals in a pod will work together as a team to round up schools of fish into tight balls upon which the dolphins can feed. When not chasing prey or performing impressive leaps, dolphins are able to rest one side of their brain at a time. This allows them to sleep while remaining conscious enough to surface and breathe.

Moby Dick

Sperm whale image

The strange-looking sperm whale can be forgiven for having such a bulbous head, given that it has the largest and heaviest brain of any living animal! And its record-breaking statistics don’t stop there – capable of diving for up to two hours at a time, the sperm whale can dive to depths of 3,000 metres, making it the deepest-diving mammal. The largest of the toothed whales, the sperm whale is famed in literature as Herman Melville’s Moby Dick, but sadly it is classified as Vulnerable on the IUCN Red List, primarily as a result of historic and present-day hunting.

Sea scars

Risso's dolphin image

A somewhat unusual-looking mammal, Risso’s dolphin can be identified by its long, pointed flippers, bulbous, beakless head, and the conspicuous scars present all over its body. These markings are thought to be caused by bites from other individuals of its kind during playing or fighting, but some scars could be the result of squid bites.

White whale

Beluga whale image

Although it is also known as the white whale, the beluga whale is actually born with dark grey to bluish- or brownish-grey colouration, only achieving the striking white hue as it matures. It is one of just a few cetaceans with a flexible neck, and it is capable of pursing its lips to suck up prey. The beluga whale is sometimes referred to as the sea canary because of the high-pitched twittering noises it produces.

On the brink

Baiji image

The baiji, or Yangtze River dolphin, is a very shy and graceful freshwater dolphin species with a very long, narrow, slightly upturned beak and small eyes placed high on the face. Sadly, it is thought that the Critically Endangered baiji could actually now be extinct. In 1999, only four individuals of its kind were observed, and an intensive search of its range in 2006 resulted in none being seen. The major threats to the baiji are considered to be illegal fishing using electricity, and being caught as bycatch in fishing nets.

Ocean giant

Blue whale image

We couldn’t possibly finish this round-up of ten incredible cetaceans without including the biggest of them all – the blue whale! The biggest animal to have ever lived, the blue whale has a heart the size of a small car and is capable of eating more than 4 tonnes of krill per day during the summer months. Whereas some cetacean species communicate using a series of high-pitched clicks and whistles, the blue whale produces a variety of low-frequency sounds, which may also serve the purpose of sensing the environment and detecting prey.

Is your favourite whale or dolphin not featured here? Then why not comment below to let us know what it is and why you love it!

If you’re looking for a fun challenge, check out ARKive’s ocean-themed scavenger hunt – there may well be a few cetaceans hidden in there!

Find out more about whale and dolphin conservation:

Kathryn Pintus, ARKive Text Author

Feb 2
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Endangered Species of the Week: North Atlantic right whale

Photo of North Atlantic right whale group

North Atlantic right whale (Eubalaena glacialis)

Species: North Atlantic right whale (Eubalaena glacialis)

Status: Endangered (EN)

Interesting Fact: The North Atlantic right whale can grow to a massive 16 metres in length and 70 tonnes in weight.

The North Atlantic right whale is one of the rarest large whales in the world. Like other members of the Balaenidae family, this species uses plates of fibrous ‘baleen’ on each side of its upper jaw to strain tiny prey items from the water. The North Atlantic right whale feeds at northern latitudes in summer, migrating south to calving grounds in the winter. Female North Atlantic right whales give birth to a single calf around once every three years.

The common name of this species comes from it being considered the ‘right’ whale to hunt, as it is easy to catch and floats when dead, yielding large quantities of oil and baleen. Centuries of hunting reduced the North Atlantic right whale population to fewer than 350 individuals by 2008, and the species is now virtually extinct in the eastern North Atlantic. Although hunting is now banned, the North Atlantic right whale still faces threats from entanglement in fishing gear, collisions with boats, pollution and climate change. Measures are in place to protect it, such as fishing gear regulations and changes to shipping lanes, but it is not yet clear whether these have been effective.

Find out more about the North Atlantic right whale and its conservation at WWF – North Atlantic right whale.

See images and videos of the North Atlantic right whale on ARKive.

Liz Shaw, ARKive Text Author

Feb 8
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In the News: Noise pollution causes stress to whales

New research has shown that the noise produced by ships causes chronic levels of stress in whales.

North Atlantic right whale image

North Atlantic right whale

Stress hormone

Whales use sound to communicate, locate food and to navigate. Previous studies have shown that the noise produced by human activities can cause whales to change their calling patterns, but these most recent findings are the first that demonstrate that noise pollution actually causes physical harm to whales.

Scientists used specially trained scent-detection dogs to locate and collect the faecal balls of North Atlantic right whales in the Bay of Fundy, Canada. During 2001, noise pollution in the Bay of Fundy fell dramatically, as marine traffic was halted following the September 11th attacks. Faeces gathered during this quieter period showed a significant reduction in the level of stress hormone being produced by the whales.

North Atlantic right whale image

North Atlantic right whale group

Harmful levels of stress

Noise levels in our oceans, produced by ship’s propellers, military sonar and underwater explosions, have increased tenfold since the 1960s. The stress that the current noise levels are causing could be detrimental to the health of whales in the long term.

Instant responses to stress – like running away from a tiger – can be life-saving,” explains Dr Rosalind Rolland, lead author on the study. “But if it becomes chronic, it causes profound depression of the immune system, making them vulnerable to disease, and it depresses reproduction.”

North Atlantic right whales are currently one of the world’s most endangered species of whale, with less than 500 remaining. Dr Roland believes that damage caused by noise pollution could further impede the recovery of this species.

North Atlantic right whale image

North Atlantic right whale breaching

A solvable problem?

While there are currently no international standards on the level of permitted noise pollution in our oceans, Dr Rolland believes the problem is a solvable one. Improving the efficiency of ship engines would not only reduce the level of noise, but also reduce the level of fuel consumption. However, with up to 50,000 large ships travelling our oceans every day, this problem may take some time to rectify.

Read more on the story in The Guardian – Shipping causes ‘chronic stress’ to whales.

Find out more on the BBC news website – Whales ‘stressed by ocean noise’.

View images and videos of the Northern Atlantic right whale on ARKive.

Becky Moran, ARKive Species Text Author

Jan 13
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In the News: Proposed quota could save whales

A proposed quota market could help to reduce the number of marine mammals killed each year, by allowing conservation groups to ‘purchase’ whales lives.

Common minke whale image

Common minke whale (Balaenoptera acutorostrata)

A price tag on whales

Despite a global ban on commercial whaling introduced in 1986 by the International Whaling Commission (IWC), whaling still continues today. While a certain number of whales are allowed to be caught by indigenous peoples, countries such as Iceland and Norway continue to catch whales commercially. Japan continues to hunt whales by exploiting a loophole, hunting whales under an exemption for “scientific” whaling.

The number of whales caught each year has even increased since the ban was introduced, almost doubling to 2,000 individuals when compared with the numbers caught in the early 1990s.

The proposed quota system would set limits on the number of whales each country could hunt, and these quotas could then be traded and bought between countries, or by environmental groups. By selling their quota, whalers would then be able to make a profit without killing the animals.

Fin whale image

Fin whale being processed

Sustainable quotas

While scientists propose that this quota system may actually reduce the number of whales killed each year, some conservationists may not be happy with the placing of a ‘price tag’ on the life of a whale. Currently, the profit from whaling stands at around $13,000 (£8,500) for a minke whale, and $85,000 (£55,400) for an endangered fin whale.

Scientists say that by using the money environmental organisations usually spend on anti-whaling operations to purchase whale quota, the number of whales caught could potentially be reduced to zero.

The proposed quotas would be issued at sustainable levels, with the majority being issued to both whaling and non-whaling IWC member nations, and the remainder being auctioned with the proceeds going to whale conservation.

Fin whale image

An endangered fin whale

An end to the deadlock?

A previous attempt to introduce a whaling quota in 2010 failed due to objections from anti-whaling groups who felt that quotas would legitimise commercial whaling. Scientists hope that the proposed tradable whaling quota would break the deadlock, creating a market that would be economically and ecologically viable to both sides of the whaling argument.

Read more about this story in The Guardian, Quota market could save whales.

Read the original article in Nature: Conservation science: A market approach to saving the whales.

View images and videos of whales on ARKive.

Becky Moran, ARKive Species Text Author

Oct 19
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In the News: Scientists raise estimate of humpback whale numbers

Scientists have increased their estimate of the number of humpback whales in the North Pacific Ocean, according to a report published in the journal Marine Mammal Science.

Photo of humpback whales, two adults breaching

The revised estimate follows analysis of data compiled in 2008 as part of the largest survey ever undertaken to assess humpback whale populations in the North Pacific.

Photographic survey

The original study, known as the ‘Structure of Populations, Levels of Abundance and Status of Humpbacks’ (SPLASH), was a three-year project involving scientists from a number of different countries. The project used photographs to determine whale numbers, relying on the unique fluke patterns of the whales to identify individuals.

By matching photos from the species’ northern feeding grounds around the Pacific Rim with photographs of the same individuals in the warm tropical waters of their southern feeding grounds, the scientists were able to produce an estimate of the overall humpback whale population.

Photo of humpback whale fluke

The pattern of pigmentation on a humpback whale’s tail fluke is unique and can be used like a ‘fingerprint’ to identify individuals

The 2008 study originally estimated humpback whale numbers in the North Pacific at just under 20,000 individuals, based on a preliminary examination of the data. However, the new report indicates the population to be over 21,000, or possibly even higher.

According to Dr Jay Barlow, a researcher at the NOAA Southwest Fisheries Science Center in La Jolla, California, “These improved numbers are encouraging… We feel the numbers may even be larger since there have been across-the-board increases in known population areas and unknown areas have probably seen the same increases.”

Photo of humpback whale swimming

Humpback whale recovery

One of the major targets of the whaling industry, the humpback whale population was decimated by commercial whaling during the 20th century. However, the new population estimate shows a significant improvement on the 1,400 individuals recorded at the end of commercial whaling in 1966.

Although the humpback whale is still vulnerable to a range of threats, including marine pollution and climate change, these figures give encouraging evidence that the species is recovering from overexploitation.

Photo of a pair of humpback whales with extended throat pleats

This latest revision to the study provides an accurate estimate for humpback whales in an entire ocean that could not have been possible without researchers working together to pool data,” said John Calambokidis, one of the founders of Cascadia Research.

While populations of some other whale species remain very low, this shows that humpback whales are among those that have recovered strongly from whaling.”

View the original Marine Mammal Science article.

Read more on this story at Eurekalert – New, higher estimates of endangered humpback whales in the North Pacific.

View photos and videos of the humpback whale on ARKive.

Liz Shaw, ARKive Species Text Author

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