Cetacean Daily


Every day I will choose a cetacean to write about.

This page can also be found on Facebook.

I do take requests! If there is any specific cetacean you would love to see me write about, just comment which one below and I will get to it !

AUGUST 7TH, 2012: THE COMMERSON DOLPHIN (Cephalorhynchus commersonii)

These dolphins can be found in shallow waters along the southernmost tip of South America and around the Kerguelen Islands in the Indian Ocean. Those found around the Kerguelen Islands are larger than the South American variety, and may be a subspecies. They can often be found in naturally protected waters or harbors, sometimes entering the mouths of rivers. These dolphins prefer more coastal waters, and are most commonly found in the Straits of Magellan, the Falkland Islands, and around Tierra del Fuego, often around kelp beds. While they may look like porpoises with their stocky body shape and their small, indistinct rostrum, the Commerson’s dolphin is unmistakably part of the dolphin family with its bold, outgoing behavior. Because of its striking black and white patterns, this dolphin is also called by other names such as the Skunk dolphin and the Piebald dolphin. Typical coloration of an adult would be a black colored head, with a large black area sweeping back from the dorsal fin to the flukes. It has a white patch on its throat that travels beneath its pectoral fins, then sweeps upwards, covering the whole midsection of the dolphin in white, with a small black patch on the underside that may come up slightly to the sides of the dolphin. At birth, these dolphins don’t have the flashy black and white pattern, but are grey, black, and brown. As it grows older, it will become black and grey, with the grey patches developing into the white coloration that the adults possess. The underside of a male Commerson’s dolphinSex can be distinguished in these dolphins based on their markings. In males, the black marking around the genital area will be shaped like a teardrop. The black marking on females is shaped more like a rounded arrowhead. Females of this species are also generally larger than males. Unlike most dolphins, the dorsal fin of the Commerson’s dolphin is wide and rounded. It may curve back slightly, though some individuals have a less rounded find that is almost triangular in shape. Their pectoral fins are rounded as well, and are a solid black on both the top and the undersides. They have anywhere from 108-138 teeth. These dolphins have a wide range of foods as part of their diet. They will consume various sea life such as fish, squid or octopus, crustaceans such as shrimp, and some other invertebrates as well, most likely foraging near the sea floor for their meals. Being dolphins, they are quite active and can swim very quickly, usually around the surface of the water. Commerson’s are active breachers, and may breach repeatedly in a short period of time. They may even surf, riding breakers close to shore or heavy swells out at sea. Bowriding is a common behavior, and they may also swim behind vessels, playing in the wake. Underwater, a Commerson’s dolphin may engage in swimming upsidedown or spinning while swimming. Gestation is about 11-12 months with this species. At birth, Commerson’s dolphin calves are fairly large – almost half the size of their mothers. They can measure anywhere between 22 to 30 inches in length (56 – 76 cm). These dolphins can live into their late teens. In both Chile and Argentina, these dolphins are sometimes hunted. Though illegal, their meat is occasionally used for crab bait. Entanglement in fishing nets also poses a threat.

*I did not write this about Commerson Dolphins. Whenever I went to go write it my mom was rushing me and so I just got it from a website… now I cannot find the website to credit them.

AUGUST 6TH, 2012: THE ORCA WHALE (Orcinus orca)

With only humans as their predators, there is a reason these whales have the nickname “killer” whale— orcas are very efficient hunters of the sea, known to even attack young giant blue whales. Despite having the “whale” at the end of their name, Orcas are classified in the dolphin family and is (not surprisingly) the largest dolphin, weighing in at 27-33 ft and 8,000-12,000 pounds! The Orcas skin is mostly black with distinctive white patches. Orcas have stocky bodies and a rounded head with a distinctive beak. They have a tall, falcate (sickle-shaped) dorsal fin and large, paddle-like flippers. The dorsal fin of the male is taller (up to 6 ft tall) and more upright than that of the female (whose dorsal fin is up to 4 ft tall). The males are always larger than the females, making them the largest member of the entire dolphin family. Orca whales are known for their extremely close knit and extremely complex social group. Swimming in pods of 6-40 members, these bonds last for life, and protect the sick, young, and injured from any danger. Male Orcas have a life expectancy of 50-60 years, and the females prove that size doesn’t matter with their life expectancy of 90 years. Orcas can dive to a depth of 100 feet (30 m) in order to hunt. Orcas commonly breach (swim at very fast speeds toward the surface in order to rise above the surface of the water and then fall back onto the surface, splashing and making noise). Spyhopping (poking the head out of the water to look around) and tail slapping are also common orca activities. The purpose of these activities is unknown, but then again, does there really need to be a purpose? Again size doesn’t matter when it comes to speed… Orcas are exceptionally fast swimmers, reaching up to 30 mph while they are chasing prey. Orca vocalizations include clicks used in echolocation, whistles, and scream-like pulses. The sounds are used to communicate with other orcas, for mating purposes, and for locating prey. Different pods (long-lasting groups of orcas) have distinctive “accents” and can recognize members by this accent.

       

AUGUST 5TH, 2012: THE MINKE WHALE (Balaenoptera acutorostrata)

Growing to be only about 25-30 feet, the Minke whale is the smallest baleen whale (with 50-70 throat grooves), but also the most abundant! The Minke Whale can be identified by its characteristic white band on its flipper (this is absent on the southern minke whales) . This white band is easily seen because it is in such contrast with the dark gray color of the rest of the whales body. Minke whales are a very dark gray color, except for on the underside where it is a bit lighter. Minke whales are stocky, having a layer of blubber several inches thick. They have 50-70 throat grooves, running from the chin to the mid-section. The minke whale has two long flippers (up to 1/8 of the body size), a small dorsal fin, and a series of small ridges along the its back near the flukes (tail). Minke whales (like all baleen whales) are seasonal feeders and carnivores sieving through the ocean water with their baleen. They filters out small polar plankton, krill, and small fish, even chasing schools of sardines, anchovies, cod, herring, and capelin. They have the same diet as blue whales. The baleen plates in the minke whale’s jaws have about 300 pairs of short, smooth baleen plates. The largest plates are about less than 12 inches (30 cm) long and 5 inches (13 cm) wide. The fine textured baleen bristles are fringed and are creamy-white with pure white bristles. Minke whales are known to travel in small pods of up to three individuals, swimming at a speed of 3-16 mph, or (when in danger)18-21 mph. Minke whales can dive for up to 20-25 minutes, but usually make shorter dives, lasting about 10-12 minutes. Just before diving, minke whales arch their back to a great degree, but the flukes do not rise out of the water. Minke whales makes very loud sounds, up to 152 decibels (as loud as a jet taking off). They make series of grunts, thuds, and raspy sounds, usually in the 100-200 Hertz range. These sounds may be used in communication with other minke whales and in echolocation. Minke whales live at the surface of the ocean in all but polar seas.

Minke Whales

AUGUST 4TH, 2012:THE MAUI’S DOLPHIN (Cephalorhynchus hectori maui)

The Maui’s Dolphin (a subspecies of the Hector Dolphin), is the worlds smallest and rarest of all marine dolphins. With a total population of around 100, and around 1 human induced death per year, the chances for recovery for these playful and highly intelligent animals are slim. This animal is severely threatened by fisheries bycatch, and recent sensitivity analysis has predicted extinction within the next few decades unless all net fishing (including gillnet and trawl fishing) is banned within its range. The Maui’s dolphin has a mickey mouse shaped dorsal fin, a gently rounded snout, and a solidly built body. While most of the Maui’s day consists of feeding, they have been seen multiple times playing with things such as seaweed, chase other dolphins, blow bubbles, fight and jump. With their small body, they grow to be about 4-5 feet and weigh up to 110 pounds. The sides and back of this dolphin are light grey, with white “flames” reaching up along the sides of its body. The underside is whitish, while the face, flippers, the dorsal fin and fluke (tail) are all black. There is a crescent-shaped black mark between eyes and blowhole.The subspecies is found in inshore waters, including river mouths, estuaries, harbors and shallow bays, commonly within about 5 nautical miles of the shore. While the mother and calves will travel together during nursery years for protection, the Maui’s dolphin normally travels in a pod of about 5 individuals. Calves live on their mother’s milk for up to a year, although they learn to eat fish and squid after about 6 months. Females mature sexually at 7-9 years old. Like most dolphins, the Maui’s dolphins have a slow reproduction rate, with a female producing 4 calves in her 20 year life span… this is just enough to replace the lives of the dolphins that have human induced deaths, which i making it a struggle for their survival. The dolphins do not have a “song” but they do produce clicks that are thought to be used for communication.

AUGUST 3RD, 2012: THE BLUE WHALE (Balaenoptera musculus)

Earth’s largest animal ever known to exist, the Blue Whale dominates the Ocean with its size of up to 100 ft and weight of 200 tons. This giant marine mammal gets all of this weight from a very exclusive diet of krill. Being that the Blue Whale is a baleen whale, meaning they have frigid plates of baleen (the stuff our fingernails are made of) attached to their upper jaw that is used to filter all the food from the water. Unfortunately, even with a lifespan of 80-90 years, the Blue Whale is an endangered whale species, like most large whale species. The name of these magnificent beings is a bit deceiving… from under the water, these whales are blue but above water they are a blue-ish gray color with white-gray spots. The underbelly has brown, yellow, or gray specks. During the winter in cold waters, diatoms stick to the underbelly, giving it a yellow to silver- to sulfur-colored sheen; they are sometimes called “sulfur bottom”. They have a very small, falcate (sickle-shaped) dorsal fin that is located near the flukes (tail). Blue whales have long, thin flippers 8 feet long and flukes that are 25 feet wide. Blue whales can dive for about an hour at a depth of 350 ft, and how fast they get there is astounding. These enormous mammals move can move up to 30 mph! Blue whales emit very loud, highly structured, repetitive low-frequency sounds that can travel for many miles underwater. They are probably the loudest animals alive, louder than a jet engine. These songs may be used for locating large masses of krill and for communicating with other blue whales, especially in order to attract and find mates. Along with being the largest animal ever to exist, they are also the loudest!

Photo: A young blue whale

AUGUST 2ND, 2012: THE BELUGA WHALE (Delphinapterus leucas)

With an average lifespan of about 25-30 years old, these magnificent cetaceans are born gray or even brown, but turn to white when they become sexually mature. One of the smallest of all whale species (growing to be about 15 feet), beluga whales are extremely social beings, living in pods of about a dozen members, but can grow to hundreds! The beluga’s body is stout and has a small, blunt head with a beak, a well-defined neck, and a rounded melon. They have no dorsal fin, which makes swimming under Arctic sheets of ice a much easier task. The flippers are short, rounded, and wide. The fluke (tail) is wide and deeply notched. With a nickname like the “sea canary” these whales have an amazing reputation of their songs, which can be heard even above the waves, and have been known to make the hulls of boats vibrate. Belugas have the loudest song of all the toothed whales, made up of clicks, whistles, and clangs that travel for miles. Belugas are mildly slow swimmers, moving on average of about 2-6 mph, but when needed can have short bursts of speed of up to 14 mph for 15 minutes. Belugas live in frigid Arctic and sub-Arctic waters, but some populations migrate south to warmer water in the summer. Beluga’s Arctic habitat overlaps with narwhal’s habitat. (The narwhal is its closest relative.) Belugas also travel up northern rivers into brackish (partly salty) water and estuaries (where a river meets the seas) to hunt prey during the summer. Belugas sometimes migrate with bowhead whales.

AUGUST 1ST, 2012: THE PACIFIC WHITE- SIDED DOLPHIN (Lagenorhynchus obliquidens)

Pacific white-sided dolphins, Lagenorhynchus obliquidens (Gill, 1865), have short, rounded, thick beaks containing 23-32 small, rounded slightly-curved teeth in each side of their upper and lower jaws. These dolphins are energetic and quite active and are frequently seen leaping, belly flopping, and somersaulting through the ocean and air. They are strong, fast swimmers and enthusiastic bow riders, often staying with moving vessels for extended periods of time, pleasuring sailors and passengers with the magnificent beauty of their attractively marked bodies. Their backs are black and their sides are light gray with thin, white stripes that extend from above the eye along the sides, widening towards the tail; their belly is white. They have black beaks and lips and a black ring around each eye. Pacific white-sided dolphins’ dorsal fins are tall and sharply hooked, and are located at the center of their backs. The leading edge is black and the rear portion is light gray. Their flippers are small and curved and rounded at the tips. Their flukes (tails) are notched in the center. Pacific white-sided dolphins are often found in large schools or pods of 90-100. The pods are made up of animals of both sexes and all ages. Since they share the same range, they are most commonly seen with northern right-whale dolphins and are often also seen accompanying other dolphins and large whales. They are considered residents in some parts of their range, notably Monterey Bay external and off southern California and northwestern Baja California. These resident populations are joined by transient groups from other areas from fall to spring.

Photo: Tuesday February 21, 2012: The Pacific White-Sided Dolphin</p><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br />
<p>Pacific white-sided dolphins, Lagenorhynchus obliquidens (Gill, 1865), have short, rounded, thick beaks containing 23-32 small, rounded slightly-curved teeth in each side of their upper and lower jaws. These dolphins are energetic and quite active and are frequently seen leaping, belly flopping, and somersaulting. They are strong, fast swimmers and enthusiastic bow riders, often staying with moving vessels for extended periods. Pacific white-sided dolphins are attractively marked. Their backs are black and their sides are light gray with thin, white stripes that extend from above the eye along the sides, widening towards the tail; their belly is white. They have black beaks and lips and a black ring around each eye. Pacific white-sided dolphins' dorsal fins are tall and sharply hooked, and are located at the center of their backs. The leading edge is black and the rear portion is light gray. Their flippers are small and curved and rounded at the tips. Their flukes (tails) are notched in the center. Pacific white-sided dolphins are often found in large schools or pods of 90-100. The pods are made up of animals of both sexes and all ages. Since they share the same range, they are most commonly seen with northern right-whale dolphins and are often also seen accompanying other dolphins and large whales. They are considered residents in some parts of their range, notably Monterey Bay external and off southern California and northwestern Baja California. These resident populations are joined by transient groups from other areas from fall to spring.

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