Amazon River Dolphin

The Amazon River Dolphin is one of the four (possibly five) species of freshwater Dolphin found in the world. They live in the Amazon basin and go by a handful of other names, including Boto and Boutu.

Inia geoffrensis

"Pink Dolphin" is yet another name for the species, due to the coloration that many of the individuals exhibit. The precise cause of the pinkness is not known, but Dolphins in murkier water tend to be more pink than those in clearer areas. Some are even as bright as flamingos!

Amazon River Dolphins differ from other freshwater Dolphins in that they have unfused neck vertebrae. This trait allows them to turn their heads from side to side and give them extra maneuverability. They can also paddle their fins in different directions, which gives them the ability to move around submerged tree roots and through very shallow spots when the rivers flood over areas that are normally above water.

The social structure of the species is dependent on the time of year. During the flood season they tend to be solitary hunters. This is because the fish are able to disperse much farther through the new marshes, giving the Dolphins more hunting area. When the waters recede, some dolphins come together in small groups in order to share the more concentrated hunting areas. Adult Dolphins have no major predators (besides humans) and thus do not need to rely on large pods for safety and protection.

Amazon River Dolphin

Amazon River Dolphins are prominent in local legends. One popular story tells that the Dolphin turns into a handsome young man at night, who always wear s hat to cover his blowhole. He comes ashore and seduces young women, often impregnating them. During the daytime he returns to the river and the women are left under a magical spell.

Legendary or not, the Dolphins are facing some problems. Some fisherman deliberately kill them so that they do not need to compete for catches, while other Dolphins get inadvertently tangled in fishing equipment. They are also facing habitat destruction, fragmentation due to dam building, and troubles arising from the chemical runoff of mining operations. A full population survey has not been done, and the species is listed as Data Deficient.

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IUCN Status : Data Deficient
Location : South America
Size : Body Length up to 8ft (2.5m)

Classification : Phylum : Chordata -- Class : Mammalia -- Order : Cetacea
Family : Iniidae -- Genus : Inia -- Species : I. geoffrensis

Blue Whale

Balaenoptera musculus

Happy World Oceans Day everybody! And what animal could represent the oceans better than the largest one in them? Meet the astonishing Blue Whale, the biggest creatures to have ever lived!

Blue Whales can reach lengths of up to 100ft, and weigh nearly 400,000lbs. That is incredible! Their hearts are the size of a small car, and their tongues can weigh as much as an elephant! In fact, right at birth they are already one of the largest animals on the planet. A newborn can measure over 25ft long and weigh 3 tons. (They also will grow 200lbs every single day!)

It is amazing to think that an animal so massive has a diet that is based exclusively on tiny little crustaceans called Krill. During the Arctic summers, they can consume up to 4tons of Krill in a single day! They feed by gulping a huge amount of water into their mouths, expanding their mouths and belly out in the process. They then push the Krill up into their baleen plates and strain the water out, leaving only the tasty little crustaceans behind.

Blue Whales can be found in all of the world's oceans, and they often migrate long distances between the poles and the equator every year. They typically travel alone, but are sometimes found in very small groups. Even if they are alone, they can still find one another with relative ease, considering they are the loudest animals out there. Their low frequency, 188 decibel sounds can be heard hundreds of miles away!

Comparison between an average Blue Whale, a human, and  a Hector's Dolphin

So we've already learned that the Blue Whale is the largest animal, and the loudest. But did you know they are also one of the most long lived? Scientists estimate that their average lifespan is 80-90 years, and that ages of well over 100 are common.

Unfortunately, Blue Whale populations aren't doing so hot. They were absolutely decimated during the commercial whaling boom, with hundreds of thousands being killed before the ban. Hunting of the species has been outlawed since 1966, but recovery has been slow. Blue Whales are listed as Endangered, and there may be less than 10,000 left in the entire world, with most being found in the Northern Hemisphere.

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IUCN Status : Endangered
Location : Oceans Worldwide
Size : Length up to 98ft (30m), Weight up to 200tons (180 metric tons)

Classification : Phylum : Chordata -- Class : Mammalia -- Order : Cetacea
Family : Balaenopteridae -- Genus : Balaenoptera -- Species : B. musculus

Dusky Dolphin

Lagenorhynchus obscurus

The Dusky Dolphin is a small little Cetacean that rarely grows longer than 2m. They can be found in coastal waters throughout the Southern Hemisphere, and are divided into three subspecies based on location. These groups live near New Zealand, in the Indian Ocean, and off of South America.

The species is known for its acrobatic skill and they are frequently seen leaping and jumping in groups. They are also very fond of boats, and like to swim and tumble alongside them. Dusky Dolphins are fast swimmers, and can reach speeds of up to 20 knots.

Dusky Dolphins live in interesting social groups. At night when they swim closer to shore their group is very small, numbering somewhere between 6 and 15 individuals. But during they day they swim to deeper water and join up with other groups in order to cooperatively hunt, play, and socialize. These gatherings can include several hundred dolphins. At night they break up again into their smaller sections.

The small social groups themselves seem to be strong, but there are no strong bonds between mated pairs. Dusky Dolphins are promiscuous breeders, and males compete with each other over females.

There are no good population estimates for the Dusky Dolphins. As a result, we don't know for sure how much hunting for food and bait, and gill-net tangling has affected their numbers.

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IUCN Status : Data Deficient
Location : Coastal waters in the Southern Hemisphere
Size : Length around 6ft (1.8m)

Classification : Phylum : Chordata --Class : Mammalia -- Order : Cetacea
Suborder : Odontoceti -- Family : Delphinidae -- Genus : Lagenorhynchus -- Species : L. obscurus

Bohaskaia monodontoides

Bohaskaia monodontoides

The animal that we're going to learn about today has been extinct for around 3 million years-- but it bears a very striking similarity to some of the creatures that are still swimming around in the Earth's oceans, and also gives scientists some insight into where those modern animals came from.

Bohaskaia monodontoides is known from just a single skull that was unearthed in Virginia is 1969. It wasn't until very recently that it was studied using modern methods, and the species was only just named in spring 2012. The skull looked similar to that of a Beluga or Narwhal, yet was still different enough to be recognized as a different genus and species entirely.

Belugas and Narwhals, as you may know, live in cold waters. B. monodontoides swam in warmers seas, yet shared many of the same physical traits. Interestingly, another extinct whale Denebola brachycephala also hailed from warmer parts (the fossils were found in Baja, Mexico). It now appears that this particular group of whales evolved in the more temperate waters, but were eventually driven north were they adapted to the climate and survived. How this happened, and when it happened is not yet known, but it is pretty amazing to think that the warm-water origin discovery was due in part to a single fossil found over 40 years ago!

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Status : Extinct for 3 million years
Location : North America

Classification : Phylum : Chordata -- Class : Mammalia -- Order : Cetacea
Family : Monodontidae -- Genus : †Bohaskaia -- Species : †B. monodontoides

Shepherd's Beaked Whale

Tasmacetus shepherdi

The Cetacean World is all abuzz this week! The Shepherd's Beaked Whale, a very rare and elusive species, has just been photographed alive for the first time ever. This is all thanks to the Australian Antarctic Division research team, who stumbled across some of the surfacing whales while hunting for their much larger, Blue Whale cousins.

This species lives in deep waters near New Zealand and Australia; their distance from shore is one of the reasons that they are so rarely seen. The Beaked Whales were first discovered in 1937, but have only been seen alive a scant handful of times. Most of what we know about the species comes from beached carcasses.

One of the most exciting things about the filming is that we now know that they are social animals. It was speculated that they were solitary, or lived in very tiny groups. This time the researchers discovered a pod of 10-12 individuals!

Understandably, not much else is known about the Shepherd's Beaked Whale, though the research time hope to publish more about their findings in the future.

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IUCN Status : Data Deficient
Location : Australia and New Zealand
Size : Length up to 20ft (7m)

Classification : Phylum : Chordata -- Class : Mammalia -- Order : Cetacea
Family : Ziphiidae -- Genus : Tasmacetus -- Species : T. shepherdi

Gray Whale

Eschrichtius robustus

As it is Mother's Day, we're going to learn about one really awesome mother from the Animal Kingdom-- the Gray Whale!

Gray Whale breeding season takes place in November and December, and happens while the Whales are wintering in warmer waters near the Equator. Females gestate for a whopping 13.5 months and give birth to a single calf while in their wintering grounds the following year. Calves are born in safer waters off of Baja, Mexico that are free from predators, and the mothers will help lift their infants up to the surface so that they can breathe... at least until they become stronger swimmers. Calves are around 4ft long at birth, and grow very quickly. They can drink up to 80 gallons of milk a day, and that milk is 53% fat!

Eventually, the mother an calf must travel back to colder climates in order to feed. The wintering waters are safe for giving birth, but that is because there is so little food, and thus very few predators. All Gray Whales migrate, and they actually take part in one of the greatest animal migrations in the world, travelling as far as 12,500 miles (20,000km) round trip each year. Females and calves are the first to leave the warm winter waters, destined for the nutrient rich seas of the north. But the trip is not easy! Not only is the swim difficult for the calves due to it's distance, it is also incredibly dangerous thanks to all the predators (like Killer Whales) that are out to get them.

Calves remain with their mothers for around a year, and will themselves take about 8 years to reach sexual maturity. One fact that I found particularly interesting is that the female Gray Whales are often larger than the males, which is unusual for Cetaceans. Sperm Whales, for example, have some of the most ridiculous sexual dimorphism of any mammal.

Gray Whales also have a very distinctive look to them, thanks to the various parasites and growths that collect on their skin. Calves are born completely smooth, and will collect their barnacles and lice as they age. Doesn't sound especially pleasant, does it?

Currently, Gray Whales can only be found in the Pacific Ocean. Before the growth of Commercial Whaling they also lived in the Atlantic, but they are now extinct in that particular area. Gray Whales almost disappeared from the planet completely, but they are now protected and their population is slowly rebounding. Boat collisions, fishing gear entanglement, habitat degradation, and the effects of climate change all continue to impact the species.

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IUCN Status : Least Concern
Location : Pacific Ocean
Size : Length up to 50ft (15m)

Classification : Phylum : Chordata -- Class : Mammalia -- Order : Cetacea
Family : Eschrichtiidae -- Genus : Eschrichtius -- Species : E. robustus

Wholphin

Wholphin

I'm sure you've heard of hybrids like Ligers and Mules, but what about Wholphins? They are the result of crosses between two ocean-dwelling mammals- Bottlenose Dolphins and False Killer Whales. I should note, however, that the False Killer Whales (like regular Killer Whales) are members of the Oceanic Dolphin family along with the Bottlenoses, so the relationship isn't as far off as one might think.

While this hybrid might appear in the wild, we only know of them definitively from two individuals living at Sea Life Park in Hawaii. Back in 1985 a female Bottlenose and a male False Killer Whale lived in the same tank, and were performers in the park's aquatic show. No one expected the 14ft Whale and 6ft Dolphin to mate, but the surprise result was Kekaimalu. She herself actually gave birth to a 3/4 Bottlenose offspring in 2005 (She had two previous calves, one died shortly after birth, and one lived till the age of 9). That makes Kekaimalu and Kawili Kai the only known captive Wholphins in the world.

Wholphins are interesting because they area true mix of the species. They grow to a size somewhere in between that of the two species (Kekaimalu's calf was the size of a 1-year-old Bottlenose when she was but 1 month old!). They have an intermediate gray color, and their teeth also fall right down the middle- False Killer Whales have 44, Bottlenose Dolphins have 88, but Kekaimalu has 66!

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IUCN Status : Not Listed

Location : Hawaii

Classification : Phylum : Chordata -- Class : Mammalia -- Order : Cetacea
Family : Delphinidae -- Genus : Pseudorca, Tursiops

False Killer Whale

Killer Whales, or Orcas, are actually Dolphins. The same is true for False Killer Whales. They are one of the largest members of the Delphinidae family, and males can grow as long as 20ft.

Pseudorca crassidens

Though they share part of a common name and some physical similarities, False Killer Whales and Killer Whales really aren't that closely related. They belong to separate genera. False Killer Whales have rounded heads with no beaks, tall dorsal fins, and dark coloration. They live in groups that can number into the dozens, and sometimes intermingle with other dolphins, like Bottlenoses. They feed mainly on cephalopods and large fish, using echolocation to locate and capture prey.

One rather interesting fact about False Killer Whales is that the world first learned of them from fossils. Live identification didn't occur until 15 years later! As you might guess, they aren't an exceptionally common species, though they can be found in temperate and tropical oceans world. For example, of the 18 species of dolphin and toothed whale found around Hawaii, they are the least populous.

According to the IUCN, there is not enough data to effectively evaluate the population of the species. They are uncommon, but also have a massive range, which makes getting exact numbers difficult, and makes it hard to determine how the species is being affected by factors like bycatch and antropogenic sound. A drastic population decrease could be incredibly troublesome for the species, because they are already uncommon, because they mature very slowly (males take about 18 years), and because they breed infrequently.

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IUCN Status : Data Deficient

Location : Temperate and Tropical Oceans

Size : Length up to 20ft (6m), Weight up to 1,500lbs (700kg)

Classification : Phylum : Chordata -- Class : Mammalia -- Order : Cetacea
Family : Delphinidae -- Genus : Pseudorca -- Species : P. crassidens