Harbor Seals
Harbor seals are marine mammals that have spotted coats in a variety of shades from silver gray, black to dark brown. They reach 5 to 6 feet in length and weigh up to 300 pounds. Harbor seals are dimorphic, with the male being slightly larger than the female. They are true, or crawling seals, which means they have no external earflaps. True seals also have small flippers, and move on land by flopping along on their bellies. They breathe at the surface and hold their breath while diving. They can dive to 1,500 feet for up to 40 minutes, although their average dive lasts 3 to 7 minutes. Their scientific name basically means 'sea calf' or 'sea dog.' This nickname is fits them well, as these seals closely resemble a dog when their head is viewed at the surface of the water.
When the harbor seal pup (baby seal) is born, it has a coat that closely resembles the adult coat. Some have a longer, softer white or gray coat (lanugo) when born, but they shed that coat within about 10 days.
Harbor seals are found across the Northern Hemisphere in both the Atlantic and Pacific Oceans. In the northeast Pacific, they range from Alaska to Baja California, in Mexico. They live near-shore coastal waters and frequent sandy beaches, mudflats, bays, and estuaries. Some harbor seals even live in certain areas of Europe such as Finland.
The total harbor seal population in the northeast Pacific is estimated to be 330,000, in California the estimated population was 40,000, and in Europe the estimated population was 6,000 in 1997.
Harbor seals spend about half their time on land and half in water, and they sometimes sleep in water. They may sleep most of the day on the beach to keep safe from the predators that hunt them, and go into the water only a couple of times each day to hunt for food. Harbor seals don?t have a permanent place to live but they usually are found in small groups, but sometimes occur in numbers of up to 100 to 500. Their average life span is around 25 years, although some have lived for over 30 years. However, males seem to live shorter lives, probably because of the added physical stress of fighting during mating season.
The Harbor Seal is both a predator and a prey. They are very vital in the food chain. Seals eat a lot of fish and prevent over population, and they are a great source of food to animals such as orca whales, great...
... middle of paper ...
... high tolerance to carbon dioxide in the tissues, they have the ability to store large amounts of oxygen in the muscle tissues, and they have the ability to make their lungs collapse when air is expelled before they dive, which helps to prevent the bends. To help see in dark and murky waters, the seals have special adapted eyes that make them able to see in such conditions. To guard against very cold water temperatures, harbor seals maintain a thick layer of fat beneath their skin, giving them a thick sausage shape. To make the harbor seals less noticeable to predators, their coats sometimes blend in with the rocks or sand they?re lying in. To help them find food easier, they have a keen sense of smell. Without these adaptations, who knows if the Harbor Seal would still exist today.
Works Cited:
*Hanan, D. (1999). Pacific Harbor Seals. Alolkoy Publishing Co. PP 12-59.
*King, J. (1983). Seals of the World. British Museum (Natural History) and Cornell University Press. PP 20-26.
*Internet: Sea World web site.
www.seaworld.org/animal_bytes/harborsealab.html April 20, 2001
*Internet: The Marine Mammal Center web site.
www.tmmc.org/harborsl.htm April 20, 2001
The nature of the long- necked seal is very shy and they have retiring behavior, the features and geography of the Loch Ness fully support the animal’s reluctance and timid actions. The animals are more likely to appear on warmer days, this also results in the appearance of people which can account for the recorded findings in Scotland. The speed of these animals, over twenty knots, can also account for why their identity can be mistaken for other animals or why there are so many theories (Shovlin 28). A Weddell seal, a species of Antarctic seal, have been known to hyper oxygenate their blood stream for long dives, up to half an hour below the freezing ice. This relates to the long-necked seal because it illustrates how they could have survived the freezing temperatures of the loch for so long, and with being below the surface it accounts for the rare sightings (Shucker). The mystery of Loch Ness is slowly, but surely being uncovered by new scientific findings and the piecing together of well- known
Hawaiian monk seals, Neo Monachus schauinslandi, are no ordinary species. They are Hawaii’s state mammal and are currently endangered. The Hawaiian Monk seal is rare because of many factors, which include overhunting, getting trapped in fishing nets, and overhunting of their favorite food, lobsters. Because of their rarity, the Hawaiian Monk Seal is a main attraction to tourists all over the world. Found in Hawaii, this monk seal is one of the two species left of the ancient seals. Grouped into the earless seal category, the Hawaiian Monk seal has two other cousins, the Caribbean Monk Seal (extinct), and the Mediterranean Monk Seal (critically endangered). The Hawaiian Monk Seal has a lifespan of 25-30 years, weighs 500-600lbs,
Guadalupe fur seals only live on rocky coasts and in caves found along shores. Out of all of the nine species of the seals, the Guadalupe have been the only ones sighted in the northern hemisphere. Meanwhile, all of the other fur seals are in the southern hemisphere. These seals tend to only live in tropical weather and swim in saltwater. While they aren’t on shore, they dive to an average maximum 17 meters for about 2.5 minutes. After that time they have to surface for air.
Southey, Clive. The Newfoundland Commercial Seal Hunt: An Economic Analysis of Cost and Benefits. Issue brief. Print.
Orcinus orca is the scientific name for the massive marine mammal. Orcas are not rare, but have declining numbers in some areas (Martin.) Orcas are found from the Artic Ocean to the Antartic Ocean. (Britannica) They belong to the Delphinidae, or dolphin family, which is the largest of their species. Female orcas grow to be at the most 15 feet, and weigh up to 4 tons, but the males can grow as large as 20-30 feet, and weight up to 8 tons. (Martin) The color of the orca is white in some spots, black on the majority of the body, and gray just behind the dorsal fin. It is white on the chin, belly and the eye. The white patch above the eye is usually mistaken for the eye, and may confuse their prey, but acts as a camouflage for the eye. The name “killer whale” makes people tend to believe that this is a viscious man-eating mammal, yet it is one of the most shrewd, docile and playful species of the marine mammals. The orca is sexually mature at 10-15 years of age, much like humans, which is 12-13 years of age. They tend to mate year round, and is able to have a calf every two years. It is interesting to know that lactation of the mother lasts 12 or more months (Wynne.) The life expectancy of orcas is 45-50 years of age.
Orcas, or killer whales are majestic giants of the sea. They are actually the largest type of dolphin. They have long black bodies with distinct white patches near their eyes. A killer whale can be up to 32 feet or more in length, and weigh up to 12,000 pounds. Females are a bit smaller, but live longer (Gorman). The name “killer whale” apparently came not because it is a vicious whale, but because it preys on whales. They do not have any natural predators, and they are considered the “top dog” of the ocean. Not even the great white shark stands a chance against these superb killers. “Unlike sharks, killer whales are cautious hunters, sometimes spending hours harassing a 1,000-pound sea lion so it can easily be drowned” (Francis). Orcas use many hunting tactics that are unique to their species, which is what makes them invincible.
Almost 4% of Hawaiian Monk Seals are dying off each year. These seals need food to survive, just like any other species. Humans are fishing so much in Hawaii that these wonderful creatures have nothing to eat. Most of their diet consists of ocean animals which humans take away by fishing. Fishing is having a negative effect on The Hawaiian Monk Seal, because fishing is not being practiced responsibly, so we should reduce the amount of fish being taken out of the water.
Now. I will tell you about dolphins and killer whales traits. First, let me start off by their both mammals. Dolphins and killer whales live in a pod, as well as they’re both carnivores. Although they both have dorsal fins, dolphins have a round dorsal fin, while on the other hand, killer whales have tall, wide dorsal fins. Now, let’s talk about their color of skin,dolphins have striped skin, and killer whales have black and white markings on their skin. Although, dolphins and killer whales are gorgeous animals, they are becoming threatened and endangered.
- Pagano, A. M., G. M. Durner, S. C. Amstrup, K. S. Simac, and G. S. York. 2012. Long-distance swimming by polar bears (Ursus maritimus) of the southern Beaufort Sea during years of extensive open water: Canadian Journal of Zoology 90:663-676. doi: 10.1139/z2012-033http://www.nrcresearchpress.com/doi/abs/10.1139/z2012-033#.UxOE1ZWPLoo
When you see a dolphin, you are in awe, but what sort of questions do you ask? How do they swim so fast, what do they eat, where do they live? First, the anatomy of a dolphin. We’ll start with a dolphin’s teeth. Dolphins have eighty to one-hundred cone-shaped teeth. These teeth are set up in a position to interlock and hold slippery fish in its mouth. Because the teeth interlock like that, and the teeth are as sharp as they are, dolphins cannot chew their food. Therefore, they must result to swallowing their food whole. To a dolphin, an open mouth is a sign of aggression, and clapping jaws are an even greater sign of aggression. This rarely happens unless it is during mating season because dolphins talk without opening their mouth.
A bottlenose dolphin’s pectoral flippers are used to steer and stop. The lobes of the dolphin’s tail are called “flukes”. The dorsal fin helps the dolphin maintain its balance as it swims. Muscles of the back help the dolphin flow through water.
Shirihai, H. and B. Jarrett (2006). Whales, Dolphins and Other Marine Mammals of the World. Princeton, Princeton University Press. p.185-188.
Leopard seals (Hydrurga leptonyx) are a species of ice-obligate seals that are widely distributed in Antarctic and sub-Antarctic waters (Hückstädt, 2015). The most recent circumpolar estimate of leopard seal abundance suggests more than 35,000 individuals, and there does not appear to be a declining trend on these numbers. The IUCN, for this reason, list the leopard seal as Least Concern (Hückstädt, 2015).
The Humpback Whale, Megaptera novaeangliae, is part of the marine mammals group. They are found in oceans all over the world, they live in open waters. Even though they are mammals, they do not live on land (Monterey Bay Aquarium). Humpback whales are known for their magical song that can travel great distances. These gentle giants are omnivores, their main diet is krill. They are mostly found near coastlines feeding on tiny shrimp-like krill, plankton and small fish. Humpbacks migrate annually from summer feeding grounds near the poles to warmer winter breeding water closer to the Equator. Humpback whales are powerful swimmers, and they use their massive tail fin, called a fluke to propel themselves through or even out of the water! Mothers and their young swim close together, often touching one another with their flippers with what appears to be gestures of affection. Even though it takes more than one year for a humpback whale to grow fully, mother whales leave them after one year (National Geographic).
When Indo-Pacific Humpback Dolphins are first born, they are dark gray and get lighter as they grow older, sometimes this will cause spots (WCD). According to Whitfield on page 114, when the Indo-Pacific Humpback dolphin is young it has a normal streamlined body figure, but when it grows older it start to form fatty tissue humps. They have the average lifespan of 40 years (WCD). The Indo-Pacific dolphin can be between 6 ½ feet to 10 feet long with 120 teeth in their long beak. Using their long beak to eat, these dolphins swim up to the shallow waters and hunt for fish (Whitfield 114). Indo-Pacific dolphins are not the only type of dolphins that pray on the