Dugong
The dugong is a marine mammal which they share the same ancestors to elephants. 55 million years ago, the evolution of dugong start from living on land then, move to the water. Since then, they had never returned to the land, like dolphins and whales
General appearance of dugong
Ears : The dugong have small ears but do not have a pinna. There are small openings on both sides of the head, behind the eye. The ear of dugong can be absorbed the sound well in the water which makes the dugongs a one of marines that can communicates underwater.
Eyes : There are 2 small eyes on both sides of the head with a thin eyelid that can be functioned which help to see well both underwater and above the water including the dim place. Once the dugongs swim above the water for a long time, their body will excrete the excess minerals to maintain the body’s balance of the minerals. Those excess minerals will be excreted as mucus from eyes which look like dugongs are crying when they were caught.
Nose : The nose of dugong locate at the end of the top of the head. There are 2 nostril, which have thick pads that can be functioned. The thick pads are closed when diving and breathing above the water which only the top of the head part can be seen above the water. They are breathing by blow out the used air and inhale the new air in. This will take just only 3 seconds so that they can dive under the sea about 6 minutes long.
Mouth : The mouth locate at the dorsoventral (lower) part of head. The upper lip is a large and thick which looks like a pig’s nose. These nose muscles can be well controlled so that can help to grasp the seagrass into the mouth that is suitable for eating. The lower lip is a cartilage bar covered with soft tissue that is used for digging sand.
Teeth : The dugong has 6 pairs of molars that they are gradually growing and getting eroded as the time goes by. So, the old dugongs will have only 2-3 pairs of teeth left. The function of dugongs’ teeth are for cutting down the seagrass. The juvenile(young) dugong had 2 pairs of incisor teeth at the front of the upper jaw which are called fangs or tusks. The front pair of incisor teeth are smaller and will be eroded gradually and gone at the age of 12-15, while the back pair of small incisor teeth will be existed throughout the dugong’s life. Therefore, the dugong’s teeth are very important in the age determination. Because only the teeth that are exists throughout their life.
Skin and skin color : The skin layer of the dugong is very thick with rough and short hairs all over the body like elephant skin. There are lots of hair around the lower part of the lip which is used to feel or find their food. Dugong has a grayish brown skin. The upper part of the body, such as the head, neck, the upper part of the front legs and the tail are darker than the lower part of the body.
Body shape : Dugong bodies are chubby but, front and back part are leaner than the center part of the body. This helps dugong to move in the water easily. The dugongs do not have a dorsal(back) fin, their tails are divided into 2 part parallel to the ground, waving up and down to swim in order to move forward. The maximun body length is approximately 3 meters, their weight are about 400 kilograms.
Gender appearance : We can determine from the distance between the anal and the genital opening. The distance between the anal and the genital opening of male dugong is longer than female and the position of the anal and genital opening of female are very close.
Breast : The breast and nipples of the dugong are located on both thigh of their legs, which can be found in both male and female. The nipples of young female dugongs are like small lump then expand when they are pregnant.
General biology of dugong
Size and weight: The maximum length is 3.3 meters(in Thailand, 2.87 meters) and the maximun weight is around 400 kilograms(in Thailand, 358 kilograms). There is not much differences between males and females. The newborn size is 1-1.5 meters and about 20 kilograms according to the report(in Thailand, 0.97 meters and 14 kilograms).
Food and habitat: Dugongs eat various type of seagrass and sometimes seaweed. The wild dugongs eat about 3-5% of body weight per day whereas the captive dugongs can eat up to 10% of body weight per day. The dugong usually live near the shore where there are lots of seagrass.
Biology and Behavior: The mature age of Dugongs is 9-10 years olds. The gestation period is around 13-14 months with only one offering per gestation. The newborn dugongs will learn how to eat seagrass the same time they start drinking breast milk. The dugong mothers will take care of their baby around 2 years. Their life span is about 70 years old. The dugong usually live in a small groups of 5-6 and they can live together in the large group of more than 100 but, the living alone dugong can be found sometimes. The average swim speed is 10 kilometers per hours, dugong usually prefer to swim with short distance