Sirenians

These adaptations help sirenians control their buoyancy and maintain their horizontal position in the water. citation citation Living sirenians grow between 2.5 and 4.0 meters long and can weigh up to 1,500 kg.

Both cetaceans and sirenians are fully aquatic and therefore are obligate water dwellers.

Description Sirenians have major aquatic adaptations : the forelimbs have modified into arms used for steering, the tail has modified into a paddle used for propulsion, and the hindlimbs (legs) are but two small remnant bones floating deep in the muscle.

Feeding Typical dugong feeding area in Moreton Bay Dugongs, along with other sirenians, are referred to as " sea cows " because their diet consists mainly of sea-grass.

Marine Mammal Medicine, 2001, Leslie Dierauf and Frances Gulland, CRC Press In sirenians, the lungs and diaphragm extend the entire length of the vertebral column.

Most species have a dorsal fin to prevent themselves from turning upside-down in the water. citation citation The flukes of sirenians are raised up and down in long strokes to move the animal forward, and can be twisted to turn.

Sirenians have been observed eating dead animals (sea gulls), but their diets are made up primarily of vegetation.

The cushion pads of the feet contain cartilaginous nodes and have similarities to the acoustic fat found in marine mammals like toothed whales and sirenians.

The ear ossicles are pachyosteosclerotic (dense and compact) and differently shaped from land mammals (other aquatic mammals, such as sirenians and earless seals, have also lost their pinnae).

The elephants are thought to be the closest living relatives of the sirenians.

They may also feed on fish. citation A dugong feeding on the sea-floor Sirenians are referred to as "sea cows" because their diet consists mainly of sea-grass.