Oceanic dolphin
| Oceanic dolphin |
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| Clymene Dolphin propelling out of the water |
Oceanic dolphins are any of the marine mammals in the Family Delphinidae, a large family encompassing all oceanic dolphins, including Orca Whales and some species of porpoise. Though dolphins are diverse and many, they are all extremely similar in actions and reactions, but varying in size and weight by a large degree. Family Delphinidae travels through the furthest reaches of the oceans; battling predators, training with the military, assisting humans, and many number of things worldwide. Dolphins are social and intelligent creatures, not so much unlike humans, but efficiently more so. The social grouping and communication of dolphins is so far ahead of what man can comprehend that they have been considered as a threat to our existence off the ocean. Dolphins efficiency in every aspect of life displays their dominant intelligence and capabilities, somehow dolphins have been learning over the years and seemingly passing their knowledge onto later generations. Scientists have been studying dolphins blatantly for many years but have recently begun to notice the truly impressive nature of the Family Delphinidae and all the species it encompasses. Dolphins have always been a well known species, but researchers have for the last few decades been studying more in depth these creatures of the ocean. Many marine biologists have begun taking dolphins as the prime subjects of their research, perhaps so that man can learn from the incredible diversity and intelligence of these marine mammals that we take for grant it as friendly pets to swim with. Though all the species in Family Delphinidae are extremely loved by many countries and cultures, there is so much more in-depth research that can be informed on dolphins, Orca Whales, and porpoises that man is just now beginning to learn.Cite error: Invalid <ref> tag; invalid names, e.g. too many
Body Design
Family Delphinidae envelops many different species of dolphin, some of which are considered whales rather than dolphins, all of which can greatly vary in length and weight. The largest dolphin can be nearly thirty feet long, weighing about eleven tons, while the smallest dolphin, a mere four feet, weighs only about ninety pounds; of course the species and location play a part in their size and weight. The body of a typical dolphin is bluish grey with sensitive skin that is shed every two hours to allow more speed while swimming. A dolphin's body is designed for just that- speed, they are designed with the purpose of quick travel with little exertion.[2]
They have a sleek, streamlined, tornado-like body that reduces friction in the water. The head of a dolphin has a rounded top called a "melon" that assists in echolocation, and a spout projectile called the rostrum, the eyes are placed near the edge of the mouth with the ears directly behind. The rostrum on a dolphin is the mouth and "nose" of the dolphin marked by a crease in the skin. A dolphin's teeth are interlocking and not for chewing food but simply for grasping the food. The teeth are not replaced throughout the dolphin's entire life. Their skin is smooth and sensitive to touch, with no sweat glands or hair throughout. The outer layer of skin, called the epidermis, is about fifteen times thicker than that of the typical mammal on land. The coloration is bluish grey to a darker grey on top, all fading into white on the bottom. This specific coloring is a type of camouflage, called countershading, hiding the dolphin from the surface and from the bottom by blending. Though their skin is different in many ways, similar to humans, dolphins' skin peel away and flake off as the old and dead cells are replaced. Their skin is also shed every two hours, decreasing resistance to water and increasing swimming ability. Cite error: Invalid <ref> tag; invalid names, e.g. too many
On the top of the dolphin is the dorsal fin and the blow hole. Dolphins require air and use the blowhole to breathe just above the surface by contracting the muscle flap that covers it, providing an air-tight seal. A dolphin has several fins; the dorsal fin, the pectoral fins or flippers, and the flukes. A dolphin's dorsal fin is located in the center of the back with a curved shape, it is made entirely of connective tissue with no bones or muscles at all, and provides balance while the dolphin swims. The pectoral fins are similarly placed and the equivalent to human forelimbs, but they are slightly curved and shaped like a triangle. Located on the sides of the dolphin, they assist in steering and stopping and are maintain body heat and circulation. The flukes, also known as the tail of the dolphin, are flat lobes of connective tissue on the end of the dolphin. Muscles move the flukes to propel the dolphin through the water quickly. Cite error: Invalid <ref> tag; invalid names, e.g. too many
Life Cycle
Dolphins have a similar life cycle to that of land mammals. Dolphins are born live, not in eggs, and stay close to the mother until maturity. Some species of dolphin can only reproduce every two to three years, others can mate any time of the year. Before mating, which often takes place during spring, the male dolphin often courts the female by swimming with her and sometimes petting each other. The dolphin gestation period varies slightly among species but can last between ten and seventeen months. During birth, at which time female dolphins of a pod will surround the mother to protect her and the calf, the dolphin calf comes out tail first, to make sure the surrounding female dolphins have enough time to push the calf to the surface to breathe. A few minutes after birth, calves can swim and breathe without assistance and swims close to their mother. As mammals, dolphins produce milk for their young, depending on the species the mother can nurse the calf anywhere between six months and two years. The dolphin calf remains with the mother after weaning for another three months to eight years, until it matures, which can take five to ten years. After maturity is reached, the dolphin will most of the time remain with the pod, eventually finding a suitable mate and reproducing. The life span of a dolphin is usually thirty years, but depending on the species they can live between twenty and fifty years. Death can be a result of old age, infections, ulcers, tumors, parasites, diseases, disorders, or even heart disease. [3]
Ecology
As the Family Delphinidae encompasses so many species of dolphins, the ecology greatly varies throughout the world. Most dolphins live in temperate or tropical regions, with very few living in colder regions along the coast and in the midst of the large ocean. In each region, dolphins feed on small fish and cephalopods, also sometimes eating small rays and even sharks. The natural predators for dolphins are sharks; though in many cases larger species of dolphins, such as the orca whales and false killer whales, become the predators to smaller dolphins species, such as the bottlenose dolphin. Of course, as for many marine species, man has also become the main predator for dolphins, but as intelligent creatures they have passed down information on how to escape man-made hunting tools and traps. Dolphins are social creatures and so travel in pods through the ocean. Dolphins provide much for their habitat. The hunting habits of these creatures keeps the populations of small species under control so that the surrounding environment can maintain neutrality. Dolphins have also been known to defend against their natural predators, sharks. Sharks and dolphins typically do not live in the same region, so dolphins provide a safe environment for swimming and for living. Dolphins also forage along the ocean floor and destroy some of the left over toxicities for the marine environment, such as the dying coral that can infect the surrounding ocean and fish. These creatures have been intensely studied in accordance to their relationship with the surrounding wild life and environment as a whole. The social aspects, reproductive habits, foraging, and predator avoiding habits continue to expand year by year, along with the ecological aspects of the Family Delphinidae. Cite error: Invalid <ref> tag; invalid names, e.g. too many
Dolphins and Humans
Over many years dolphins and humans have established a level of bonding and interaction at various levels. Dolphins are extremely social creatures and therefore have a tendency towards social nature. In captivity and out in the wild, dolphins have been known to interact with humans. In the wild, dolphins have been seen helping fishermen by circling around a large school of fish and forcing them into the nets, keeping what was left for themselves. Though, in captivity there is a much greater level of interaction between humans and dolphins. Dolphins are intelligent creatures, all species are capable of being trained, though some species have been known to act out harshly towards a trainer or ill-mannered person (i.e. Orca Whale). There are programs with designed to use dolphins in therapy, swimming with dolphins can help heal people who have been through a great traumatic experience, and in fact dolphins have been known to surround and protect physically impaired or pregnant people in the water. Dolphins can also be trained to act and perform, as well as play and swim with humans in captivity. Many parks include dolphin shows and cases where people can pay to swim with the dolphins, where the dolphins will perform many tricks that include the humans participation. Dolphins and humans communicate by a sense of touch and sight, such as hand signals. The dolphins are trained by positive reinforcement to react to a specific hand signal or being touched by a trainer. Of course, as an intelligent species, dolphins are more easily trained than some other wild animals, but they are still wild animals and will attack if in a stressful or angering situation. Dolphins have also been trained for military use over the years. The Navy utilizes them in searching for mines, assistance in the water, and rescue missions. Though the use of dolphins is much more humane today, in the past, bombs have been sent to enemy lines underwater by strapping the device to a dolphin.Cite error: Invalid <ref> tag; invalid names, e.g. too many
Unfortunately, like many other nearly harmless species, dolphins are often hunted and killed by man. Though in most of the world hunting dolphins for game is illegal, as well as killing them, in some corners of the ocean they are still hunted and killed for several reasons. killed by fishermen who do not want to compete with the dolphins for the surrounding fish population, and some are also caught in fishermen's' nets, whether by accident or purposefully ends in death. In many cases of fishing, dolphins are killed and used as bait for crab fishing. In many parts of Asia, dolphins and whales are considered delicate meat and so are sold and used for food, dolphin meat has been found in cans of tuna even in the United States. The construction of dams has also been the cause of death for many dolphins, they are drawn by the use of loud equipment and are often trapped, or found without food. Recently, the major cause of death and dysfunction in dolphins has been the pollution that man has allowed to leak into the ocean, causing deformation in many cases and most of the time, death.[4]
Video
How Smart Are Dolphins?
Gallery
Killer Whale
(Orcinus Orca)
Genus: Orcinus
False Killer Whale
(Pseudorca crassidens)
Genus: Pseudorca
Short-Beaked Common Dolphin
(Delphinus delphis)
Genus: Delphinus
Pilot Whale
(Globicephala melas)
Genus: Globicephala
References
- ↑ Delphinidae Wikispecies. Web. Last updated December, 10 2012. Unknown Author.
- ↑ Dolphin Facts BioExpedition. Web. Date of access March 22, 2014. Unknown Author.
- ↑ [1] Whalefacts.org. Web. March 22, 2014 Date of access. Unknown Author.
- ↑ Why Are Dolphins Hunted And Killed? WhaleFacts.org. Web. April 6, 2014 Date of Access. Unknown Author.
