From the large orca to the small vaquita, dolphins encapsulate a large range of unique species. These sociable creatures have demonstrated incredible intelligence and creativity - but, like many other creatures in this world, are facing immense danger due to human action.
Having once lived on land, dolphins “re-entered” the oceans. There are remnants of finger bones in their flippers, as well as a forearm, wrists and a few remnant leg bones inside their bodies. There are 43 identified species of dolphin currently swimming around the world’s waters. While most live in the shallower waters of tropical and temperate oceans, there are also seven freshwater species that live in rivers.
Photo credit: Flickr | Dena Burnett
Dolphins are very social creatures that live and travel in groups, with large pods amounting to a thousand members or more. Their carnivorous diet means that they feed on creatures like fish, squid and crustaceans – large dolphins like the Orca can consume up to 500 pounds of fish a day. They have also honed some creative feeding methods, including a method known as sponging, which involves dolphins holding a sea-sponge tightly in their beaks and poking them in the sandy sea bed to chase out fish hiding under the surface.
Known for their intelligence, the evolution of a dolphin’s brain is surprisingly similar to humans. They can produce both whistles for communication and clicks for sonar at the same time – the equivalent of a human speaking in two voices and two different pitches, having two different conversations. Being mammals, they have to come up to the surface to breathe, and can expel air from their blowholes (which is an evolved nose) at speeds topping 100 mph.
Another unique characteristic of the dolphin is its enjoyment of play. A game of catch between a pod is common, and there have even been recorded cases of dolphins engaging in play with other species. For instance, dolphins have engaged in play with humpback whales, swimming on the nose of the whales, who then raise themselves out of the water so the dolphins slide down their heads back into the water. Dolphins also often follow boats in order to collect the fish that is churned out from the stream, but they also seem to just go along for a speed boost, riding the bow-waves like surfers.
Photo credit: Flickr | Heather and Mike
Whilst dolphins have few natural enemies, humans pose the biggest threat to their survival. Pollution, fishing and hunting has rendered their survival uncertain and in the case of the Yangtze River, for instance, has led to species extinction. For some species, poaching poses a further threat to their survival. The Narwhal dolphin, for instance, has a large ivory tusk which has made the species an object of pursuit. Consequently, the only remaining populations are in the Greenland Sea and Baffin Bay. Confinement poses a further threat to these intelligent creatures. The popularity of activities such as dolphin shows and swimming with dolphins means that many are kept in captivity and are often subjected to immense suffering. Depression, physical illness and aberrant behavior have all been recorded as a result of the creatures being removed and isolated from the large social groups they usually co-exist with. Such claustrophobic conditions have caused unnatural aggression in the otherwise gentle creatures.
There you have it, a quick overview of dolphins! Until then, so long and thanks for all the fish.