DUSKY DOLPHIN

Dusky Dolphin Facts

Introduction

The Dusky Dolphin is very closely related to the Pacific White Sided Dolphin. 

However, the scientific studies conducted show that there are enough variations for them to be classified as two separate species. What you may not know is that their name was originally going to be Fitzroy’s Dolphin which was given to them by Charles Darwin.

Description

This is a small dolphin species and it is simple enough to identify it from other species out there. This is due to the head that is evenly sloped. It also lacks a beak at the end of the snout. They feature a bluish black color on the tail and along the back. They also have a dark band that is featured from the flanks to the tail diagonally. The belly is white with a dark color for the lower jaw and snout. They have gray from the eye to the flipper and then two white or cream stripes that run between the dorsal fin to the tail.

They are about 6 to 6 ½ feet long. They weigh from 150 to 187 pounds. The males and the females look very similar in size. The male does have a dorsal fin that is more curved than the females.

There are teeth found in both the upper and the lower jaws. They may have from 24 to 36 pairs of teeth that are very small and pointed. Usually, the upper jaw will have 2 sets less than what is found in the lower jaw.

Distribution

The Dusky Dolphin resides in the coastal waters of the Southern Hemisphere. The best known locations for them include New Zealand, the Southern region of Australia, The Southwest area of Africa, and in Tasmania. There are small populations of this dolphin living along the Western coast of South America.

They are coastal and can be located around both the slopes and the continental shelves. They stick to the warmer regions, but from time to time they have been found living in cooler temperatures as well.

Behavior

The Dusky Dolphin is very social, and their pods can be more than 1,000 members. However, it is more common to find them in much smaller numbers. They typically will range from 20 to 500 members. It is believed that the larger numbers come together for feeding and that there are plenty of subgroups within a larger pod. This allows a level of hierarchy to work for them that can be difficult for observations to fully identify.

They are very acrobatic and can be seen leaping out of the water. They are known to tumble in the air. They are also commonly found approaching boats so that they can bow ride. Playing and leaping are types of activities they often take part in as they socialize. They can swim very fast too. Communication includes the use of squeals, clicks, whistles, and squeaks. They are loud sounds and can be heard almost 2 miles away when they occur while the dolphins are out of the water.

Feeding

There are plenty of types of food that the Dusky Dolphin feeds upon. They include shrimp, squid, various fish, and anchovy. They can feed during the day or at night, and generally do so in highly sophisticated collaborative efforts. They are able to feed both at the surface of the water and at the bottom of it which gives them plenty of opportunities.

They tend to take part in efforts that involve up to 300 dolphins working as a team to successfully herd larger schools of fish. What is very interesting though is that they can change their strategies for foraging to fit the circumstances. Their communication each other is key to making sure they are able to get enough food for survival.

Reproduction

Spring is the time of year when the Dusky Dolphin is most likely to take part in mating. It takes about 11 months for the calf to be born. The males compete aggressively with each other in order to be able to mate with the females. There seems to be less involved with mating rituals with this species than with other dolphins. However, the bonds that do form seem to be apparent within a pod.

The age for matting seems to vary in different locations. It is believed that it could be determined based on food resources, stress, the length of the dolphin, and more. There needs to be additional research conducted to back up such theories. The females and their young will form nursery groups and they tend to stay in the water that is shallow so that they can rest.

The young will be fully weaned at about 18 months from the milk the mother produces. However, about 6 to 8 months of age they will be introduced to other food resources. They will be taught how to successfully hunt so that they can one day take care of their needs by contributing to the collaborative hunting efforts.

Conservation Status and Threats

It has been difficult to get a good count on the number of Dusky Dolphins in the wild. However, it is believed that they do endure huge losses of numbers due to getting tangled up with fishing nets or illegal harpoon hunting. Efforts to help with improving fishing methods has proved to be helpful. In Peru there is a huge demand for the meat of this dolphin and efforts to stop illegal killing can be difficult to implement even though it has been banned since 1996.

Some have been worried about the volumes of tourists that come to watch the dolphins around New Zealand. However, the experts don’t feel that this process has caused any major stress factors for the Dusky Dolphins to contend with. Studies that will help to identify environmental problems as well as to get a better count on the number of them are in progress. Right now, they aren’t in serious danger but hopefully conservation steps will also prevent their numbers from ever dropping low enough for them to be at risk of extinction.

Commerson's Dolphin

Commerson's Dolphin

Commerson's Dolphin Facts

Introduction

There are quite a few different names that the Commerson's Dolphin is known by. They include the Panda Dolphin, Skunk Dolphin, and the Piebald Dolphin. However, the rightful name for them is the results of the Philbert Commerson's who saw them in 1767 in the strait of Magellan and shared his information.

Description 

The size of this dolphin can be very different based on location. Some them are just shy of 4 feet long and others are a bit over 5 1/2 feet. They can weigh as much as 190 pounds. What is very interesting with this species of dolphin is that the females are usually a bit larger than the males. They body of the Commerson’s Dolphin is very round, but it is also tapered at the ends. This enables them to have a body designed to swim fast but also to conserve energy as they do so.

Their body is designed for swimming. They have pectoral fins that are short and they are well supported by connective tissues. They also have control over blood circulation through the pectoral flippers. This is believed to assist them with maintaining the right body temperature.

They have a very interesting coloration pattern to them which is black and white. This serves to offer them camouflage in the water. The coloring can also make it possible for males and females to be distinguished from each other. The males have a patch on their belly that is oval shaped. For females, this same patch is going to be in the shape of a V.

There are 29 or 30 teeth located on each side of the jaw, both up and down. As a result, the Commerson’s Dolphin will have either 116 or 120 teeth total.

Distribution

There are two main locations where you will find this dolphin living. The largest of the two populations is around the inlets of Argentina and into the Strait of Magellan close to Falkland Islands. The other population is around the Kerguelen Islands and it wasn’t discovered until the 1950s. They tend to spend most of their time in the shallow water areas. They are found around harbors, rivers, and bays too. It is rare for them to be found at depths of more than 650 feet.

Behavior

This dolphin species is believed to be very migrational. It is believed they follow the fish in the winter time that are moving to warmer waters. The Commerson’s Dolphin is very active and they swim a great deal of the time. They are often frequently seen leaping from the water. They can do a variety of acrobatics including spins, twists, and they will bow ride behind boats in the water at fast speeds.

What is very interesting is that they have even been spotted swimming upside down. It is possible that they do so in order to survey their prey possibilities in given surroundings. Since they are rarely able to be observed much other than when they surface, there isn’t much well known about their behaviors.

Feeding

Even though most of the feeding efforts are collaborative, from time to time they have been seen feeding on their own. They use various types of herding methods as a team to get schools of fish to ball up and then they can dive in and consume them. These feeding efforts usually involve smaller groups of about 15 members. Since they can swim so quickly, they are able to get food and make it look virtually effortless.

Their diet consists of small fish, shrimp, octopus, squid, marine worms, and from time to time algae. They have one of the most diverse diets of all species of dolphins. What they will consume depends on their environment, the time of year, and the amount of food available compared to the number of Commerson’s Dolphins. They are opportunistic so they will feed on what they can find in order to survive.

They are known to get food from the open water surfaces as well as from the bottom of the sea floor. No species of dolphin chews their food, instead they swallow it whole so what they get has to be small enough to do so. They will consume about 10% of their body weight daily. This is about twice as much food as most species of dolphins consume when compared to their body weight.

Reproduction

There isn’t very much information known about reproduction for the Commerson’s Dolphin. The age of maturity can range from 5 to 9 years, with the females ready for mating before the males in the same habitat. Mating can occur from September through February. When it will occur depends on their location. It takes 12 months after mating for the young to arrive, and it will be a single calf born in the winter tail first.

The young will drink milk from the mother’s body for a period of time, but it isn’t determined when they are weaned. With other species of dolphins it is generally between 12 and 18 months of age. In the wild, the Commerson’s Dolphin has a lifespan of about 10 years. In captivity the average is 18 years.

 

Conservation Status and Threats

The last survey conducted in 1984 estimated at least 3,400 of them in the Strait of Magellan. However, it isn’t known what the overall population is for them today. Even so, there are efforts in place to help ensure that they don’t see depleted number and end up vulnerable or extinct. They are red listed as a threatened species.

Such conservation efforts have focused on reducing pollution, reducing the risk of the Commerson’s Dolphin getting caught up in commercial fishing nets, and reducing issues with noise around them which can increase their overall stress levels. Other efforts focus on reducing the threat of these dolphins being hunted for their meat and oil. They have also been hunted to use as bait for crab capture. However, enforcing laws to prevent such hunting can be very hard.

Common Dolphin

Common Dolphin Facts

There are two species of dolphins that fall into the category of Common Dolphin.

Right now there is the Short-Beaked Common Dolphin and the Long-Beaked Common Dolphin that are recognized.

  
The one that may be added soon is the Arabian Common Dolphin which is only found in the Indian Ocean and the Red Sea.

Description 

The Short-Beaked Common Dolphin can weigh as much as 440 pounds and they can be up to 9 feet long. They have a very bright color to them which is very interesting. They often have patterns on them with dark gray that capes over them in a V shape under the dorsal fin on both sides of the body. Their flank is a tan or yellow color.

The Long-Beaked Common Dolphin is very similar in overall appearance. The main difference of course is the length of the beak. This species can be from 6 to 8 1/2 feet in length. They can weight from 160 pounds to 500 pounds. The males are  going to be a bit larger than the females. They have a dorsal fin that is in the middle of the back.  They too have the distinctively bright color patterns.

It can be tough to distinguish  these two subspecies of Common  Dolphins from each other. However, if you look at images of them side by side you can see how they have some variation that allow you to uniquely identify them.

Distribution 

These dolphins live in bodies of water that have a warm temperature. The Long-Beaked Common Dolphin is found close to the shallows waters. The Short-Beaked  Common Dolphin though tends to be in deeper waters up to 590 feet. They tend to do well in many areas as longs as they have enough food and warm enough water.

These dolphins don't migrate like so many other species do. However, they will move around if necessary to find food and when there is unusually cold waters. They often do return to their home range though as soon as possible.

Behavior 

The Common Dolphin is very social, and they live in large groups called pods.
The number in a pod can be several hundred or it can be in the thousands.
The largest ones number over 10,000. They have a very complex hierarchy that keep them orderly and they tend to create subgroups based on ages and other factors.

This dolphin species has been seen taking part in a variety of different behaviors. They include somersaults, pitch poling, breaching, and bow riding.
They are very active and they seem to able to move through the water almost effortlessly. They are also playful so they spend time teasing each other.

Touch and echolocation are big parts of their social interactions with each other. They seem to thrive on the connections they have with other. 
Vocalizations including whistling, whining, and clicking are very common. The dialogue though can be different based on pod and that is a very interesting element of their overall behaviors.

Feeding 

The majority of the diet for the Common Dolphin comes from schools of fish.
There can be quite a variety of species though for them to select from. What they will have access to depends of their locations. Some of these dolphins are quite picky when it comes to which ones they will eat. They will resort to other types of fish though when these they enjoy the most are hard to come by. They will also consume squid and other cephalopods.

Feeding usually occurs at night and then they will be resting during the day.
They have up to 57 pairs of teeth on both the upper and lower jaws that they can use to help them hold the prey but they don't chew their food.
What they do consume has to be small enough for them to shallow. They can consume about 5% of their body weight daily.

Reproduction 

Females can be ready for mating from 2 to 7 years of age. For the males, it can range from 13 to years old. It is believed that the length of the dolphins play more of a role in when they are mature to mate than their age. Typically, the Common Dolphin will mate when it grows to a size of 6 1/2 feet.

The common time for mating is from June to September. It takes from 10 to 11 months for the calf to be born. The young offspring can be from 2 1/2 to 3 feet long at birth. They will drink milk from the body of the mother for several months. The females can give birth every 1 to 3 years. The average   lifespan in the wild is 35 years.


Conservation Status and Threats   

There are quite a few risks at time to the Common Dolphin, and many of them are the result of human efforts. One of them is amount of pollution that continues to find its way into water. This can include chemicals and plastic. They both have a huge impact on the negative health of these dolphins. Efforts to help reduce pollution continue but still have a long way to go in order to be a success.

Along the coast of Peru, issues with them being heavily hunted for food and to use as bait for is an issue. Even with pressure on the government there, the problem continues and there is too much money being made by those involved to get them to stop the process on their own. Only when there are serious fines and jail time for such activities will there be an leverage.

Commercial fishing efforts have resulted in thousands of these dolphins being injured or killed. In the US there are protective efforts that limit fishing areas and the types of equipment that can be used. Right now the Short-Beaked Common Dolphin is considered to be least concern but that could change if conservation doesn't continue. For Long-Beaked Common Dolphin, there isn't sufficient data to be used to know their numbers in the wild. However, it is believed without such help then they too will have a hard time surviving.

Some of the conservation efforts that involve helping those that have been injured have been hard to complete. The Common Dolphin is stated to one that is very difficult to keep healthy and happy in captivity.
     


   

Atlantic Spotted Dolphin

Atlantic Spotted Dolphin 

The Atlantic spotted dolphin is very long, with a size of about 7 1/2 feet when fully mature. They can weigh from  240 to 360 with males being much larger than the females.  They develop unique spots all over their bodies as they get older.  Young ones don't any spots and those  that are mature may only have a handful. It is for this reason that the Atlantic spotted dolphin is often  misidentified.

The top of their bodies are dark gray or dark black. Underneath it is a white or cream color. On the dark part of their bodies they will have white spots and on the whitish areas they will develop dark colored spots.

Distribution 

The Atlantic spotted dolphin is only found in the ocean. They are known to live in variety of locations including the oceans around the United States, Africa, Europe, the Bahamas, and the Gulf of Mexico. They have significantly increased in numbers in the Bahamas. There are now hundreds of them when only a couple of decades there less than 100 there. It is estimated that there are more than 100,000 Atlantic spotted dolphins out there.

Some of them  that live along the Gulf of Mexico do migrate annually. Others tend to move long distances each day but not out of a need to follow a migration pattern.

Behavior

They are excellent when it comes to communication. They use a variety of loud clicks and whistles to talk with each other. They form groups of about 50 and they are also known to move around with other species of dolphins without any conflicts among them. There is a hierarchy among these dolphins that depends upon many factors including their size, age, and gender.

They are extremely protective of their young and will help each other to care for them. They also tend to do their best to protect the pregnant females from enemies including sharks.

Diet and Feeding

Their main food sources include octopus and various types of small fish. 
Most of the time they will fish at night. They also tend to hunt in groups as they have a tactic that allows them to get their prey into a big circle. Then they are able to come at these schools of fish from all angles.

Reproduction

There isn't too much known about the reproductive habits of these dolphins.
It is estimated that it takes 11 months from mating to birth. They are born without any spots but about one year of age they begin to develop. It is along this same period of time that the mothers will stop offering milk to them.

Conservation

One of the biggest threats to the Atlantic spotted dolphin is the amount of pollution that is found in their natural environment. Many types of efforts have been initiated to help clean up these bodies of water. At the same time educating the public about not polluting has also helped to reduce it. Still, there is plenty more than has to be done in order to resolve the problem.

Human interaction 

This particular species of dolphin is very timid. They have been known to come right up to humans that are visiting the areas of the Bahamas. This has become one of the main tourist attractions in the area.

Many of them are killed annually due to illegal hunting by fisherman. They want to reduce the number of them so they can product in their fishing nets. Others are accidentally captured in those nets so they may drown or become severely injured.