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Commerson’s Dolphin (Cephalorhynchus commersonii)

Commerson’s Dolphin

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 result of the Philbert Commerson 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 of them are just shy of 4 feet long and others are a bit over 5 ½ 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.

Commerson's dolphin facts

Commerson’s dolphin Cephalorhynchus commersonii

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.

sumber: http://www.dolphins-world.com/commersons-dolphin/


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